Chemistry Exam 3
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Balance the following equation: ____ P4 (g) + ____ N2O (g) --> ____P4O6 (g) + ____ N2 (g)
Chemistry Exam 3 assesses knowledge on energy requirements, chemical equations, pH levels, combustion reactions, biological molecules, and glucose metabolism. It tests analytical skills in interpreting and applying chemical principles, crucial for advanced chemistry learners.
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- 2.
How many grams H20 are produced when 35.8 g C3H8 react by the following equation? C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(g)
Explanation
When 35.8 g of C3H8 react according to the given equation, the stoichiometry of the equation tells us that 4 moles of H2O are produced for every mole of C3H8. To find the mass of H2O produced, we need to convert the mass of C3H8 to moles using its molar mass, and then use the mole ratio to find the moles of H2O produced. Finally, we can convert the moles of H2O to grams using the molar mass of H2O. The calculation yields a mass of 58.5 g H2O.Rate this question:
- 3.
Use the corresponding symbols above to complete the sentence. When a catalyst is added to the reaction ____ is reduced while ____ remains unchange.
Explanation
When a catalyst is added to a reaction, the activation energy required for the reaction to proceed is reduced, while the heat of reaction (enthalpy change) remains unchanged. A catalyst works by providing an alternative reaction pathway with a lower activation energy, allowing the reactants to overcome the energy barrier more easily. However, the overall energy change (enthalpy) of the reaction remains the same, as the catalyst does not affect the thermodynamics of the reaction.Rate this question:
- 4.
Name this functional group.
Explanation
A ketone is a functional group that consists of a carbonyl group (a carbon double bonded to an oxygen) bonded to two other carbon atoms. It is named by replacing the -e ending of the parent alkane with -one. Ketones are commonly found in organic compounds and play important roles in various biological and chemical processes. They are characterized by their reactivity and ability to undergo various reactions, such as nucleophilic addition and oxidation.Rate this question:
- 5.
Name this functional group.
Explanation
A carboxylic acid is a functional group that consists of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (OH). It is commonly found in organic compounds and is characterized by its acidic properties, as it can donate a proton (H+) to a base. Carboxylic acids are important in biological processes and are found in many essential molecules such as amino acids and fatty acids.Rate this question:
- 6.
Name this functional group. RCOOR
Explanation
The functional group in the given compound is an ester. An ester is formed by the reaction between a carboxylic acid and an alcohol, resulting in the formation of an ester bond. In the compound RCOOR, the R represents an alkyl or aryl group, and the COOR represents the ester group. Esters are commonly used in various industries, including the production of perfumes, flavorings, and plastics.Rate this question:
- 7.
Name this functional group. RCOSR
Explanation
The given functional group RCOSR is called a thioester. It is formed by replacing the oxygen atom in an ester with a sulfur atom. Thioesters are commonly found in biological systems, particularly in the metabolism of fatty acids and in the formation of peptide bonds in proteins. They play important roles in various biochemical processes and are known for their stability and reactivity.Rate this question:
- 8.
*BONUS*
Explanation
An aldehyde is a type of organic compound that contains a carbonyl group (C=O) bonded to at least one hydrogen atom. It is commonly represented by the general formula R-CHO, where R is a functional group or a hydrogen atom. Aldehydes are known for their distinctive odor and are often used as fragrances or flavoring agents. They are also important intermediates in various chemical reactions and have numerous industrial applications.Rate this question:
- 9.
Sugars and nucleotides have at least one functional group in common. Which of the following groups do they share? ketone alcohol ether
Explanation
Sugars and nucleotides share the functional group of alcohol. This is because both sugars and nucleotides contain hydroxyl (-OH) groups, which are characteristic of alcohols. The presence of this functional group allows for various chemical reactions and interactions that are important for the structure and function of both sugars and nucleotides.Rate this question:
- 10.
Identify each reaction as exothermic or endothermic. CaCO3 + 133kcal --> CaO + CO2 2 SO2 + O2 --> 2 SO3 + heat
Explanation
The first reaction, CaCO3 -> CaO + CO2, is endothermic because it requires the input of 133 kcal of energy. This means that the reaction absorbs heat from its surroundings in order to proceed.
The second reaction, 2 SO2 + O2 -> 2 SO3 + heat, is exothermic because it releases heat energy. The "heat" in the reaction indicates that heat is produced as a byproduct of the reaction.
Therefore, the correct answer is endothermic, exothermic.Rate this question:
- 11.
Name this functional group.
Explanation
An amide is a functional group that consists of a carbonyl group (C=O) bonded to a nitrogen atom (N). It is formed by the condensation reaction between a carboxylic acid and an amine. Amides are commonly found in proteins and play a crucial role in the structure and function of biomolecules. They exhibit unique chemical and physical properties, including high boiling points and the ability to form hydrogen bonds.Rate this question:
- 12.
Which of the following activities require energy?
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Walking
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Cell repair
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Breathing
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Studying
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All of the above require energy
Correct Answer
A. All of the above require energyExplanation
All of the activities mentioned in the options - walking, cell repair, breathing, and studying - require energy. Walking requires energy as it involves the movement of muscles. Cell repair requires energy as it involves the synthesis of new molecules and the repair of damaged cells. Breathing requires energy as it involves the contraction of muscles and the movement of air in and out of the lungs. Studying requires energy as it involves mental effort and concentration. Therefore, all of the above activities require energy.Rate this question:
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- 13.
Be able to label the following: R = reactants P = products Heat of reaction = ^H Activation Energy = Ea
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True
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False
Correct Answer
A. TrueExplanation
This statement is true because it correctly labels the terms R, P, Heat of reaction (^H), and Activation Energy (Ea). R refers to the reactants, P refers to the products, ^H represents the heat of reaction, and Ea represents the activation energy.Rate this question:
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- 14.
Which of the following substances are present at equilibrium?
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Ammonia, water, ammonium, and hydroxide are all present at equilibrium.
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Only ammonia and water are present at equilibrium.
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Only ammonium and hydroxide are present at equilibrium.
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Only hydroxide and hydronium are present at equilibrium.
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It is not possible to say which molecules will be present at equilibrium.
Correct Answer
A. Ammonia, water, ammonium, and hydroxide are all present at equilibrium.Explanation
The correct answer is that ammonia, water, ammonium, and hydroxide are all present at equilibrium. This means that all four substances are present in equal concentrations and the forward and reverse reactions are occurring at the same rate, resulting in a stable state.Rate this question:
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- 15.
The following chemical equation is not balance. What must be done to the equation to make it balanced? Al(s) + CuO(s) --> AL2O3(s) + Cu(s)
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Change the coefficients to 2 for Al, 3 for CuO and 3 for Cu.
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Change the subscripts of CuO to CuO2.
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Add a molecule of AlO.
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Change the state of matter in the reactants.
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Change the subscripts of Al2O3 to be AlO
Correct Answer
A. Change the coefficients to 2 for Al, 3 for CuO and 3 for Cu.Explanation
To balance a chemical equation, the number of atoms of each element on both sides of the equation must be equal. In the given equation, there are 1 Al atom, 1 Cu atom, 1 O atom, and 1 Cu atom on the reactant side, while there are 2 Al atoms, 2 O atoms, and 1 Cu atom on the product side. To balance the equation, the coefficients of Al, CuO, and Cu must be changed to 2, 3, and 3 respectively. This will result in 2 Al atoms, 3 O atoms, and 3 Cu atoms on both sides of the equation, making it balanced.Rate this question:
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- 16.
Which of the following statements best describes the concentration of ammonia and ammonium at equilibrium?
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The concentration of ammonium is increasing.
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There is no ammonium at equilibrium.
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Their concentrations are equal.
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Their concentrations are constant.
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There is no ammonia at equilibrium.
Correct Answer
A. Their concentrations are constant.Explanation
At equilibrium, the concentration of ammonia and ammonium remains constant. This means that the rate of the forward reaction (ammonia converting to ammonium) is equal to the rate of the reverse reaction (ammonium converting to ammonia). As a result, the concentrations of both ammonia and ammonium do not change over time, leading to a constant concentration at equilibrium.Rate this question:
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- 17.
What are biological catalysts called?
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Lipids
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Carbohydrates
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Proteins
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Enzymes
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Nucleic acids
Correct Answer
A. EnzymesExplanation
Enzymes are biological catalysts that speed up chemical reactions in living organisms. They are typically proteins that act as catalysts by lowering the activation energy required for a reaction to occur. Enzymes are highly specific and can catalyze a wide range of reactions. They play a crucial role in various metabolic processes, such as digestion, respiration, and synthesis of molecules. Lipids, carbohydrates, and nucleic acids are important biomolecules but do not possess the catalytic properties exhibited by enzymes.Rate this question:
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- 18.
A blood sample has a pH of 7.42. What is the concentration of hydroxide in this solution?
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3.80 x 10^-8 M
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0.870 M
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2.63 x 10^-7 M
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-2.63 x 10^7 M
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3.80 x 10^8 M
Correct Answer
A. 2.63 x 10^-7 MExplanation
The concentration of hydroxide in a solution can be determined using the equation Kw = [H+][OH-], where Kw is the ion product constant for water. Since the pH of the blood sample is 7.42, the concentration of hydrogen ions ([H+]) can be calculated using the formula pH = -log[H+]. By taking the negative logarithm of 7.42, we can find that [H+] is approximately 2.63 x 10^-8 M. Since Kw is a constant, we can divide it by [H+] to find the concentration of hydroxide ([OH-]), which is approximately 2.63 x 10^-7 M.Rate this question:
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- 19.
Which statement best describes the purpse of ATP in the cell?
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It is part of the cell membrane.
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It is the energy currency of the cell.
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It is a protein.
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It is a catalyst, speeding up the rate of chemical reactions.
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It is a component of the genetic material in the cell.
Correct Answer
A. It is the energy currency of the cell.Explanation
ATP (adenosine triphosphate) is known as the energy currency of the cell because it is responsible for storing and providing energy for cellular processes. It acts as a source of energy for various metabolic reactions and provides the necessary energy for cellular functions such as muscle contraction, active transport, and synthesis of macromolecules. ATP is produced during cellular respiration and can be quickly broken down to release energy when needed. Therefore, it plays a crucial role in providing energy for all cellular activities.Rate this question:
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- 20.
In order for many drugs to be active, they must fit into cell receptors. In order for the drug to fit into the cell receptor, which of the following must be true?
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The drug must be a complementary shape to the inceptor.
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The drug must be able to form intermolecular forces the the receptor.
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The drug must have functional groups in the correct positions.
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The drug must have the correct polarity.
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All of the above.
Correct Answer
A. All of the above.Explanation
For a drug to be active, it must fulfill multiple requirements. Firstly, it must have a complementary shape to the cell receptor it is targeting, as this allows for proper binding. Secondly, the drug must be able to form intermolecular forces with the receptor, which further enhances the binding. Additionally, the drug must have functional groups in the correct positions, as these groups play a crucial role in the drug-receptor interaction. Lastly, the drug must have the correct polarity, as this influences its ability to interact with the receptor. Therefore, all of the given options must be true for a drug to be active.Rate this question:
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- 21.
Which of the following statements best describes the concentration of ammonia and ammonium at equilibrium?
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Their concentrations are constant.
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There is no ammonia at equilibrium.
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There is no ammonium at equilibrium.
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Their concentrations are equal. (If you choose this answer you DO NOT understand the concept of equilibrium.) /cry
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The concentration of ammonium is increasing.
Correct Answer
A. Their concentrations are constant.Explanation
The correct answer is that the concentrations of ammonia and ammonium are constant at equilibrium. This means that the rate of the forward reaction (ammonia converting to ammonium) is equal to the rate of the reverse reaction (ammonium converting to ammonia), resulting in a stable concentration of both species. This is a fundamental concept of chemical equilibrium, where the system reaches a state of balance with no net change in concentrations over time.Rate this question:
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- 22.
Which of the following biological molucules are the major nutrients that make up the food that we eat? I. proteins II. nucleic acids III. steroids IV. fats V. carbohydrates
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All of these are major nutrients.
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I, II, IV, and V
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I and V
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III, IV, and V
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I, IV, and V
Correct Answer
A. I, IV, and VExplanation
Proteins, fats, and carbohydrates are the major nutrients that make up the food we eat. Proteins are essential for growth, repair, and maintenance of body tissues. Fats provide energy, insulation, and protection for organs. Carbohydrates are the main source of energy for the body. Nucleic acids and steroids are not major nutrients that make up our food.Rate this question:
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- 23.
What is the pH of a solution with a [-OH] of 4.1 x 10^-3 M?
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-11.6
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-2.39
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7.00
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11.6
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2.39
Correct Answer
A. 11.6Explanation
The pH of a solution is a measure of its acidity or alkalinity. It is calculated using the formula pH = -log[H+]. In this case, we are given the concentration of hydroxide ions [OH-]. To find the pH, we need to convert the concentration of hydroxide ions to the concentration of hydrogen ions [H+]. Since water dissociates into equal amounts of hydroxide and hydrogen ions, we can assume that the concentration of hydrogen ions is also 4.1 x 10^-3 M. Taking the negative logarithm of this concentration gives us a pH value of 11.6.Rate this question:
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- 24.
Which statement best describes how the termperature of the surroundings change as a result of the reaction represented by this diagram?
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The temperature of the surroundings decreases.
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The surroundings will become very cold.
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The temperature of the surroundings increases.
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The temperature of the surrounding does not change.
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It is not possible to predict anything about the temperature of the surroundings based on this diagram.
Correct Answer
A. The temperature of the surroundings increases.Explanation
Based on the given diagram, the reaction represented is likely an exothermic reaction. In an exothermic reaction, energy is released in the form of heat, causing the surroundings to become warmer. Therefore, the correct answer is that the temperature of the surroundings increases.Rate this question:
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- 25.
One serving (45 g) of dry wild rice contains 1.5 g of fat, 35 g of carbohydrates, and 5 g of protein. How many Calories does a serving of wild rice contain?
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166 Calories
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170 Calories
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200 Calories
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340 Calories
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370 Calories
Correct Answer
A. 170 CaloriesExplanation
One serving of wild rice contains 1.5g of fat, 35g of carbohydrates, and 5g of protein. Each gram of fat provides 9 calories, each gram of carbohydrates provides 4 calories, and each gram of protein provides 4 calories. To calculate the total number of calories in the serving, we multiply the grams of fat by 9, the grams of carbohydrates by 4, and the grams of protein by 4, and then sum them up. In this case, (1.5g x 9) + (35g x 4) + (5g x 4) = 170 calories. Therefore, a serving of wild rice contains 170 calories.Rate this question:
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- 26.
How do strong and weak acids differ?
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Strong acids dissociate a molecule in aqueous solutions and weak acids..
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Only strong acids produce hydronium in aqueous solutions.
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Strong acids donate protons and weak acids do not.
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Strong acids increase the concentration of -OH in solution
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Weak acids degrade less readily than strong acids.
Correct Answer
A. Strong acids dissociate a molecule in aqueous solutions and weak acids.. -
- 27.
Which statement best describes how aldehydes, ketones, and carboxylic acids are similar?
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They are geometric isomers.
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They are constitutional isomers.
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They are conformers
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They all contain hydroxyl groups.
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They all contain carbonyl groups.
Correct Answer
A. They all contain carbonyl groups.Explanation
Aldehydes, ketones, and carboxylic acids are similar in that they all contain carbonyl groups. A carbonyl group consists of a carbon atom double bonded to an oxygen atom. In aldehydes, the carbonyl group is located at the end of a carbon chain, in ketones it is located in the middle, and in carboxylic acids, it is located at the end of a carbon chain with an attached hydroxyl group. This similarity in the presence of carbonyl groups allows these compounds to exhibit similar chemical properties and reactions.Rate this question:
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- 28.
Which of the following molecules contain both a phenol and an ester? *may not be on test
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E
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![Chemistry Exam 3 - Quiz]()
Correct Answer
A. E -
- 29.
The blanaced chemical equation for the combustion of propane (C3H8) is given below. How many grams of carbon dioxide (CO2) are released when 35g of propane are burned in the presence of excess oxygen? (C3H8) + 5(O2) --> 3(CO2) + 4(H2O)
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0.80 g
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12 g
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35 g
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105 g
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1500 g
Correct Answer
A. 105 gExplanation
When 35g of propane are burned, according to the balanced chemical equation, 3 moles of carbon dioxide (CO2) are produced for every 1 mole of propane (C3H8) burned. The molar mass of propane is 44 g/mol, so 35g of propane is equivalent to 35/44 moles of propane. Therefore, the number of moles of carbon dioxide produced is 3 * (35/44) = 2.386 moles. The molar mass of carbon dioxide is 44 g/mol, so the mass of 2.386 moles of carbon dioxide is 2.386 * 44 = 105 g. Therefore, 105 g of carbon dioxide are released when 35g of propane are burned.Rate this question:
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- 30.
Coefficients are important components of chemical equations. What is the significance of coefficient in a chemical equation? I. Coefficients indicated the ratio of masses of molecules. II. Coefficients indicate the ratio of numers of atoms and molecules. III. Coefficients indicate the ratio or numbers of moles of molecules and atoms.
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III only
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I and II
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II and III
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I only
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II only
Correct Answer
A. II and IIIExplanation
The coefficients in a chemical equation indicate the ratio of numbers of atoms and molecules (II) as well as the ratio of numbers of moles of molecules and atoms (III). Coefficients are used to balance chemical equations and ensure that the law of conservation of mass is followed. They represent the number of molecules or atoms involved in the reaction and help determine the stoichiometry of the reaction.Rate this question:
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- 31.
Ethynyl estradiol, a synthetic hormone, is a common compound of birth control pills. Which bond in ethynyl estradiol is an alkyne?
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A
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B
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C
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D
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A and C
Correct Answer
A. AExplanation
The bond in ethynyl estradiol that is an alkyne is bond A.Rate this question:
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- 32.
What do all bases have in common?
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They contain an -OH group.
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They contain a nitrogen.
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They contain an oxygen.
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They are all salts.
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They contain a nonbonding pair of electrons.
Correct Answer
A. They contain a nonbonding pair of electrons.Explanation
All bases have in common that they contain a nonbonding pair of electrons. This is because a base is a substance that can accept a proton (H+) and donate a pair of electrons. The presence of a nonbonding pair of electrons allows the base to form a coordinate bond with a proton, forming a new bond. This is a characteristic feature of bases and distinguishes them from other substances.Rate this question:
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- 33.
Each of the following figures represents a reaction. Which reaction has the fastest rate?
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A
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B
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C
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D
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E
Correct Answer
A. D -
- 34.
Which part of the following energy diagram is changed when a catalyst is added, and how is it changed?
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I is lower.
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I is higher.
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II is higher.
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II is lower.
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III is higher.
Correct Answer
A. II is lower.Explanation
When a catalyst is added, it provides an alternative reaction pathway with a lower activation energy. This means that the energy required for the reactants to reach the transition state is reduced. As a result, the energy level of the transition state (II) is lowered, making it easier for the reaction to occur. The energy levels of the reactants (I) and products (III) remain unchanged.Rate this question:
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- 35.
Which statement best describes how aldehydes, ketones and carboxylic acids are similar?
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They are constitutional isomers.
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They all contain carbonyl groups.
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They all contain hydroxyl groups.
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They are geometric isomers.
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They are conformers.
Correct Answer
A. They all contain carbonyl groups.Explanation
Aldehydes, ketones, and carboxylic acids are all similar because they contain carbonyl groups. A carbonyl group consists of a carbon atom double-bonded to an oxygen atom. In aldehydes, the carbonyl group is located at the end of a carbon chain, in ketones it is located in the middle, and in carboxylic acids, it is located at the end of a carbon chain with an additional hydroxyl group attached. The presence of the carbonyl group gives these compounds similar chemical properties and reactivity.Rate this question:
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- 36.
Which of the following diagrams illustrates an endothermic reaction? I. II. III.
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II only
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I and II
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I and III
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II and III
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I only
Correct Answer
A. II onlyExplanation
The diagram that illustrates an endothermic reaction is II only. This is because an endothermic reaction absorbs heat from its surroundings, resulting in a decrease in temperature. In diagram II, the reaction is shown with a decrease in temperature, indicating that it is absorbing heat from the surroundings. Diagrams I and III do not show a decrease in temperature, so they do not represent an endothermic reaction.Rate this question:
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- 37.
Which of the following organic molecules contains at lease one functional group?
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All of these molecules contain at lease one functional group.
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All of these molecules except I contain at lease one functional group.
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Molecules II, III, and IV contain at least one functional group.
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Only molecules III and IV contain a functional group.
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None of these molecules contain a functional group.
Correct Answer
A. Only molecules III and IV contain a functional group.Explanation
All of these molecules except I contain at least one functional group.Rate this question:
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- 38.
Which of the following substances are present at equilibrium.
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Only ammonia and water are present at equilibrium.
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Only hydroxide and hydronium are present at equilibrium.
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Ammonia, water, ammonium, and hydroxide are all present at equilibrium.
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It is not possible to say which molecules will be present at equilibrium.
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Only ammonium and hydroxide are present at equilibrium.
Correct Answer
A. Ammonia, water, ammonium, and hydroxide are all present at equilibrium.Explanation
Ammonia, water, ammonium, and hydroxide are all present at equilibrium because these substances are involved in the reversible reaction NH3 + H2O ⇌ NH4+ + OH-. At equilibrium, the forward and reverse reactions are occurring at the same rate, resulting in a constant concentration of all four substances.Rate this question:
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- 39.
In the body, glucose is broken down in the presence of oxygen into carbon dioxide and water. The balanced chemical equation for this reaction is shown below. According to this equation, how many molecules of carbon dioxide are produced when three molecules of glucose are metabolized in the presence of excess oxygen? (C6H12O6) + (O2) --> 6(CO2) + 6(H2O)
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18
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24
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6
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12
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0
Correct Answer
A. 18Explanation
When three molecules of glucose are metabolized in the presence of excess oxygen, according to the balanced chemical equation, 6 molecules of carbon dioxide are produced for each molecule of glucose. Therefore, for three molecules of glucose, the total number of carbon dioxide molecules produced would be 6 x 3 = 18.Rate this question:
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- 40.
Not all protons in a molecule can be donated in an acid-base reaction. Below are three molecules, each with the proton donated in an acid-base reaction circled. What do these protons have in common?
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They are the only hydrogens in the molecule.
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They are all attached to the most electronegative atom in the molecule.
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The are all attached to oxygen.
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They are all attached to carbon.
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They are all in a carbon-containing molecule.
Correct Answer
A. They are all attached to the most electronegative atom in the molecule.Explanation
The protons that are donated in an acid-base reaction have in common that they are all attached to the most electronegative atom in the molecule. This is because the most electronegative atoms, such as oxygen, have a greater ability to attract electrons towards themselves, creating a partial negative charge. This partial negative charge makes the proton more acidic and more likely to be donated in a reaction.Rate this question:
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- 41.
The steps for performing stoichiometry calculations are diagrammed below: According to these steps, which of the following equations would allow you to calculate the yield of monosaccharides when 25 g of sucrose is broken down as shown in the following equation? *NOT ON TEST, BUT SIMILAR "WORKOUT" PROBLEM
Correct Answer
A. -
- 42.
A hydrogen atome without an electron is referred to as __________.
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Hydroxide
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Hydronium
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A proton
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An acid
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A conjugate base
Correct Answer
A. A protonExplanation
When a hydrogen atom loses its electron, it becomes positively charged and is referred to as a proton. Protons are found in the nucleus of an atom and have a mass of approximately 1 atomic mass unit. They play a crucial role in determining the chemical and physical properties of elements.Rate this question:
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- 43.
What is the IUPAC name of the following molecule?
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2,3-dimethyl-4-pentanol
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1,2,3,3-tetramethyl-1-propanol
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1,2,3-trimethyl-1-butanol
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2,3,4-trimethyl-4-butanol
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3,4-dimethyl-2-pentanol
Correct Answer
A. 3,4-dimethyl-2-pentanolExplanation
The IUPAC name of the given molecule is 3,4-dimethyl-2-pentanol because it correctly describes the position and number of the methyl groups. The numbering starts from the end closest to the hydroxyl group, and the methyl groups are located at positions 3 and 4 on the pentane chain.Rate this question:
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- 44.
Which of the following statements about acids in NOT true?
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An acid increases the concentration of hydroxide in solution.
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An acid is a proton donor.
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An acid increases the concentration of hydrnium in solution.
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An example of an acid is HBr.
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An acid increases the concentration of protons in solution.
Correct Answer
A. An acid increases the concentration of hydroxide in solution.Explanation
An acid increases the concentration of hydroxide in solution. This statement is not true because acids actually increase the concentration of hydronium ions (H3O+) in solution, not hydroxide ions (OH-). Acids donate protons (H+) to water molecules, forming hydronium ions, which make the solution acidic. Hydroxide ions, on the other hand, are found in bases, not acids.Rate this question:
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- 45.
Which of the following molecules contain(s) an alcohol?
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All of these molecules contain an alcohol.
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I only.
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II only.
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III only.
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Both I and II contain an alcohol.
Correct Answer
A. II only.Explanation
The correct answer is II only because only molecule II, which is an alcohol, contains an -OH group. Molecules I and III do not contain any alcohol functional groups.Rate this question:
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- 46.
What is the pH of a solution with a [H20^6] of 1.26 x 10^-4 M?
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3.90
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10.1
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-3.90
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11.9
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-10.1
Correct Answer
A. 3.90Explanation
The pH of a solution is a measure of its acidity or alkalinity. It is determined by the concentration of hydrogen ions (H+) in the solution. The lower the concentration of H+, the more acidic the solution, and the higher the concentration of H+, the more alkaline the solution. In this case, the concentration of H+ is given as 1.26 x 10^-4 M. Taking the negative logarithm of this concentration gives a pH of 3.90, indicating that the solution is slightly acidic.Rate this question:
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- 47.
Which of the following statements does NOT describe how functional groups are used in organic chemistry?
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Functional groups are used to organize and classify organic molecules.
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Functional groups are used to predict reactivity of molecules.
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Functional groups are used to predict physical properties of molecules.
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Functional groups are used in naming organic molecules.
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Functional groups are used to determine the natural abundance of a molecule.
Correct Answer
A. Functional groups are used to determine the natural abundance of a molecule.Explanation
Functional groups are used to determine the natural abundance of a molecule. This statement does not describe how functional groups are used in organic chemistry. Functional groups are used to organize and classify organic molecules, predict reactivity and physical properties of molecules, and in naming organic molecules. However, determining the natural abundance of a molecule is not a common use of functional groups in organic chemistry.Rate this question:
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- 48.
The enthalpy for the reaction described by this diagram is __________.
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Less than zero
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Exactly zero
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Very large
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Greater than zero, but not necessarily very large
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It is not possible to predict anything about the enthalpy of this equation.
Correct Answer
A. Less than zeroExplanation
The given answer is "less than zero". Based on the diagram, we can see that the reactants are at a higher energy level than the products. This indicates that energy is released during the reaction, making it exothermic. Since enthalpy is a measure of the heat energy released or absorbed during a reaction, a negative value for enthalpy indicates that heat is released, supporting the answer "less than zero".Rate this question:
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- 49.
Which of the following molecules contain(s) an ether functional group?
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All of these molecules contain an ether.
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I only.
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II only.
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III only.
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Both I and II contain an ether.
Correct Answer
A. I only.Explanation
The correct answer is "I only" because only molecule I contains an ether functional group. An ether functional group consists of an oxygen atom bonded to two alkyl or aryl groups. In molecule I, there is an oxygen atom bonded to two alkyl groups, making it the only molecule that contains an ether functional group. Molecules II and III do not have this functional group.Rate this question:
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.png "Which of the following statements best describes the concentration of ammonia and ammonium at equilibrium?")
.png "The enthalpy for the reaction described by this diagram is __________.")
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Mar 20, 2023Quiz Edited by
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Dec 02, 2012Quiz Created by
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