Chemistry IGCSE Sections 1 - 3
Quiz based on the Chemistry iGCSE 2009 specification.
Questions and Answers
- 1.
What is a mole?
Explanation
Avogadro's number is a fundamental constant in chemistry that represents the number of particles (atoms, molecules, ions) in one mole of a substance. It is approximately equal to 6.022 x 10^23 particles per mole. Therefore, the correct answer states that a mole is defined as Avogadro's number of particles.Rate this question:
- 2.
What is Avogradro's number?
Explanation
Avogadro's number is a fundamental constant in chemistry and physics that represents the number of atoms or molecules in one mole of a substance. It is approximately equal to 6*10^23, meaning that one mole of any substance contains 6*10^23 atoms or molecules. This number is important in various calculations and conversions involving moles, such as determining the mass of a substance or the number of particles present.Rate this question:
- 3.
What is the formula for mole calculations? Moles = ?
Explanation
The formula for mole calculations is Moles = mass/RMM. This formula is used to calculate the number of moles of a substance by dividing its mass by its relative molecular mass (RMM). The RMM represents the average mass of one molecule of the substance relative to the mass of one atom of carbon-12. By using this formula, the number of moles can be determined, which is important in various chemical calculations and conversions.Rate this question:
- 4.
How much volume does one mole of a gas occupy?
Explanation
One mole of a gas occupies a volume of 24dm3. This is known as the molar volume of a gas at standard temperature and pressure (STP), which is defined as 0 degrees Celsius and 1 atmosphere of pressure. The molar volume is a constant value for all ideal gases at STP. Therefore, regardless of the type of gas, one mole of it will always occupy a volume of 24dm3.Rate this question:
- 5.
Charge of NO3 ion?
Explanation
The charge of the NO3 ion is 1-. This is because NO3 is a polyatomic ion known as nitrate. Nitrate has a charge of -1, which means it has gained one electron to achieve a stable octet configuration. The negative charge indicates that the ion has more electrons than protons, resulting in an overall negative charge.Rate this question:
- 6.
What is ionic bonding?
Explanation
Ionic bonding is a type of chemical bonding that occurs between atoms when one or more electrons are transferred from one atom to another, resulting in the formation of oppositely charged ions. These ions then attract each other due to strong electrostatic forces of attraction, forming a bond. This type of bonding typically occurs between metals and nonmetals, where the metal loses electrons to become a positively charged ion (cation) and the nonmetal gains those electrons to become a negatively charged ion (anion). The strong attraction between these oppositely charged ions creates a stable and strong bond known as ionic bonding.Rate this question:
- 7.
What is the structure of an ionic crystal?
Explanation
The structure of an ionic crystal is a giant three-dimensional lattice structure. This means that the ions in the crystal are arranged in a repeating pattern, forming a network of positive and negative ions that extends in all three dimensions. This lattice structure gives ionic crystals their characteristic properties, such as high melting points and brittleness. The regular arrangement of ions also allows for the efficient transfer of electrons, making ionic crystals good conductors of electricity when melted or dissolved in water.Rate this question:
- 8.
What is a covalent bond?
Explanation
A covalent bond is a type of chemical bond formed between two atoms when they share a pair of electrons. This sharing of electrons creates a strong attraction between the bonding pair of electrons and the nuclei of the atoms involved in the bond. This attraction holds the atoms together, forming a stable molecule. Covalent bonds are typically found in nonmetallic elements and compounds.Rate this question:
- 9.
Why do substances with simple molecular structures have low melting points?
Explanation
Substances with simple molecular structures have low melting points because they have weak forces of attraction between the atoms. These weak forces, known as intermolecular forces, can easily be overcome with relatively little energy. As a result, the substance transitions from a solid to a liquid state at a lower temperature compared to substances with stronger intermolecular forces.Rate this question:
- 10.
Why do substances with giant covalent bonds have high melting points?
Explanation
Substances with giant covalent bonds have high melting points because these bonds are very strong and require a significant amount of energy to break. The atoms in the substance are held together by a network of covalent bonds, which form a continuous lattice structure. The strong covalent bonds hold the atoms in place, making it difficult for the substance to change from a solid to a liquid state. As a result, a large amount of heat energy is needed to break these bonds and cause the substance to melt.Rate this question:
- 11.
What is a metal?
Explanation
A metal is a substance that has a giant structure of positive ions surrounded by a sea of delocalized electrons. This means that the metal atoms lose their outer electrons, creating positively charged ions, and these ions are held together in a lattice structure. The delocalized electrons are free to move throughout the lattice, creating a "sea" of electrons. This arrangement gives metals their characteristic properties, such as high electrical and thermal conductivity, malleability, and ductility.Rate this question:
- 12.
Why don't covalent compounds conduct electricity?
Explanation
Covalent compounds do not conduct electricity because they do not have free electrons. In a covalent bond, electrons are shared between atoms, resulting in a stable molecule. This sharing of electrons means that there are no free electrons available to move and conduct electricity. Additionally, covalent compounds generally have no overall charge, meaning there are no charged particles, such as ions, that can carry an electric current.Rate this question:
- 13.
What is the name of the positive electrode?
Explanation
The positive electrode in a battery or an electrochemical cell is called the anode. It is the site where oxidation takes place, releasing electrons and positively charged ions. In a circuit, the anode is connected to the positive terminal of the power source, allowing the flow of electrons from the anode to the negative electrode (cathode). The anode is essential for the overall functioning of the cell or battery, as it facilitates the movement of charge and the generation of electrical current.Rate this question:
- 14.
What does one Faraday represent?
Explanation
One Faraday represents the amount of electrical charge carried by one mole of electrons. This means that if we have one Faraday of charge, we have a quantity of charge equal to the Avogadro constant (6.022 x 10^23) multiplied by the charge of a single electron. In other words, it represents a very large number of electrons, specifically the number of electrons in one mole of a substance.Rate this question:
- 15.
What is the value of one faraday?
Explanation
One faraday is a unit of electrical charge equal to 96500 coulombs. This means that if a current of one ampere is passed through a conductor for one second, it will transport a charge of 96500 coulombs. This unit is commonly used in electrochemistry to measure the amount of charge required to deposit or react with a certain amount of substance during electrolysis.Rate this question:
- 16.
What type of oxides to metals tend to have?
Explanation
Metals tend to have basic oxides. Basic oxides are formed when metals react with oxygen, resulting in the formation of metal oxides that have basic properties. These oxides can react with acids to form salts and water, indicating their basic nature. They typically have a high pH and can conduct electricity when dissolved in water. Examples of basic oxides include sodium oxide (Na2O) and calcium oxide (CaO).Rate this question:
- 17.
What is the appearence of bromine at room temperature?
Explanation
Bromine appears as a dark red liquid at room temperature.Rate this question:
- 18.
Describe the reaction of carbon in oxygen.
Explanation
When carbon reacts with oxygen, it undergoes combustion, resulting in the production of a small yellow/orange flame. The intensity of the flame and the presence of sparks may vary depending on the purity of the carbon sample. This reaction occurs because carbon has a high affinity for oxygen, and when heated, it combines with oxygen to form carbon dioxide. The release of energy during this exothermic reaction is what causes the flame and sparks.Rate this question:
- 19.
Describe the burning of sulfur in oxygen.
Explanation
When sulfur is burned in the presence of oxygen, it undergoes a chemical reaction that releases energy in the form of a bright blue flame. This combustion reaction results in the formation of sulfur dioxide gas, which is a compound composed of sulfur and oxygen atoms. The blue flame and the production of sulfur dioxide gas are characteristic features of the burning of sulfur in oxygen.Rate this question:
- 20.
Describe the reaction of Magnesium with Hydrochloric Acid.
Explanation
When magnesium reacts with hydrochloric acid, it produces magnesium chloride and hydrogen gas. The reaction is described as vigorous because it occurs rapidly and with the release of a large amount of energy. It is also exothermic because heat is given off during the reaction. This can be observed by the increase in temperature of the reaction mixture.Rate this question:
- 21.
Describe the reaction of Zinc and Iron with Hydrochloric Acid.
Explanation
When zinc and iron are mixed with hydrochloric acid, they react slowly at room temperature but the reaction becomes more rapid when heated. This reaction results in the formation of chlorides.Rate this question:
- 22.
What colour does Lithium turn in a flame test?
Explanation
Lithium turns red in a flame test because when heated, the electrons in the lithium atoms absorb energy and become excited. As they return to their ground state, they release this excess energy in the form of light. The specific wavelength of light emitted by lithium corresponds to the color red, hence giving the flame a red color.Rate this question:
- 23.
What colour does Sodium turn in a flame test?
Explanation
When sodium is subjected to a flame test, it emits a characteristic orange color. This is due to the excitation of electrons in sodium atoms. When energy is supplied to the atoms, the electrons move to higher energy levels. As they return to their original positions, they release energy in the form of light. In the case of sodium, this energy corresponds to the orange wavelength, resulting in the observed orange color in the flame test.Rate this question:
- 24.
What colour does Calcium turn in a flame test?
Explanation
Calcium turns brick red in a flame test. This is because when calcium ions are heated, they absorb energy and get excited. As they return to their ground state, they release energy in the form of light. The specific wavelength of light emitted by calcium corresponds to the color brick red, hence the observed color in the flame test.Rate this question:
- 25.
What is the test for Ammonia gas?
Explanation
The test for Ammonia gas is that it turns red litmus paper blue. Ammonia is a basic compound, and it has the ability to react with the red litmus paper, which is an indicator for acidity or alkalinity. When Ammonia gas comes into contact with the red litmus paper, it causes the paper to change its color from red to blue, indicating that the gas is alkaline in nature. This test is commonly used to identify the presence of Ammonia gas in various substances.Rate this question:
- 26.
What colour does Copper turn when mixed with Sodium Hydroxide?
Explanation
When copper is mixed with sodium hydroxide, it forms a compound called copper hydroxide. Copper hydroxide has a blue color, which is why the mixture of copper and sodium hydroxide appears blue.Rate this question:
- 27.
What colour does Iron(II) turn when mixed with Sodium Hydroxide solution?
Explanation
When Iron(II) is mixed with Sodium Hydroxide solution, it forms a green precipitate called Iron(II) hydroxide. This reaction occurs because Iron(II) ions react with hydroxide ions from Sodium Hydroxide to form the insoluble Iron(II) hydroxide compound. Therefore, the resulting mixture turns green in color.Rate this question:
- 28.
What colour does Iron(III) turn when mixed with Sodium Hydroxide?
Explanation
When Iron(III) is mixed with Sodium Hydroxide, it forms a compound called Iron(III) Hydroxide. Iron(III) Hydroxide is a brown colored precipitate, which is why the mixture turns brown. This color change occurs due to the reaction between the Iron(III) ions and the Hydroxide ions present in Sodium Hydroxide.Rate this question:
- 29.
What colour is the precipitate when silver nitrate is added to Chlorine?
Explanation
When silver nitrate is added to chlorine, a white precipitate is formed. This is because silver chloride is insoluble in water and forms a solid precipitate. The white color of the precipitate is due to the scattering of light by the particles of silver chloride.Rate this question:
- 30.
What colour is the precipitate when silver nitrate is added to Bromine?
Explanation
When silver nitrate is added to bromine, a cream-colored precipitate is formed. This is because silver bromide is produced as a result of the reaction between silver nitrate and bromine. Silver bromide has a cream color, which is why the precipitate appears cream-colored.Rate this question:
- 31.
What colour is the precipitate when silver nitrate is added to Iodine?
Explanation
When silver nitrate is added to iodine, a yellow precipitate is formed. This is because silver iodide is insoluble in water and forms a yellow solid when it is produced. The yellow color of the precipitate indicates the presence of silver iodide in the solution.Rate this question:
- 32.
What is the result when Barium Chloride is added to a sulfate?
Explanation
When Barium Chloride is added to a sulfate, a chemical reaction occurs between the two compounds. Barium Chloride is a soluble compound, while sulfate is insoluble in water. As a result, a white precipitate is formed, indicating the formation of an insoluble compound.Rate this question:
- 33.
What is the test for chlorine gas?
Explanation
Chlorine gas is known for its strong oxidizing properties, which allow it to react with various substances. When chlorine gas comes into contact with damp litmus paper, it oxidizes the dyes present in the paper, causing them to lose their color. This bleaching effect on the litmus paper is a characteristic reaction of chlorine gas and can be used as a test to identify its presence.Rate this question:
- 34.
What is an homologous series?
Explanation
An homologous series refers to a group of compounds that have similar properties due to having similar types of bonding. This means that the compounds in the series have similar chemical structures and share common characteristics. These compounds often have a similar functional group and exhibit similar chemical reactions. The properties and behaviors of the compounds within the homologous series can be predicted based on the pattern established by the series.Rate this question:
- 35.
Give three characteristics of an homologous series.
Explanation
The given answer correctly identifies three characteristics of a homologous series. First, a homologous series has the same general formula, meaning that the compounds in the series have a similar molecular structure. Second, compounds in a homologous series exhibit similar chemical properties, indicating that they undergo similar chemical reactions. Finally, there is a gradual trend in physical properties within a homologous series, such as boiling points, melting points, and solubilities, as the number of carbon atoms increases. These three characteristics are key features that define a homologous series.Rate this question:
- 36.
What are the products when Bromine reacts with Methane?
Explanation
When bromine reacts with methane, it replaces one of the hydrogen atoms in methane to form bromomethane. This is a substitution reaction where bromine acts as a halogenating agent. The reaction can be represented as CH4 + Br2 → CH3Br + HBr. Bromomethane is the main product of this reaction. Additionally, hydrogen bromide (HBr) is also formed as a byproduct.Rate this question:
- 37.
What is the test for alkenes?
Explanation
The test for alkenes is to mix them with bromine water. Alkenes are unsaturated hydrocarbons that contain a carbon-carbon double bond. Bromine water is a solution of bromine in water. When an alkene is mixed with bromine water, the orange-brown color of bromine water disappears, indicating a reaction has occurred. This reaction is known as bromination, where the bromine adds across the double bond of the alkene, resulting in the formation of a colorless dibromoalkane. This test is commonly used to distinguish alkenes from other hydrocarbons, such as alkanes, which do not react with bromine water.Rate this question:
- 38.
What is the positive result of the test for alkenes?
Explanation
When the test for alkenes is positive, it means that alkenes are present in the sample. Alkenes are unsaturated hydrocarbons that contain a carbon-carbon double bond. The test for alkenes involves adding a reagent, such as bromine water, to the sample. In the presence of alkenes, the bromine water will undergo a reaction called addition, where the bromine molecules break apart and attach to the carbon atoms in the double bond. This reaction causes the bromine water to change from its original orange/red color to a colorless solution, indicating a positive result for alkenes.Rate this question:
- 39.
What is produced when bromine reacts with ethene?
Explanation
When bromine reacts with ethene, it forms 1,2-dibromoethene. This is a compound in which two bromine atoms are attached to adjacent carbon atoms in the ethene molecule. The reaction involves the addition of bromine across the double bond of ethene, resulting in the formation of a saturated compound with two bromine atoms. This reaction is an example of an addition reaction, where the double bond is broken and new bonds are formed with the bromine atoms. 1,2-dibromoethene is a colorless liquid that is used in various industrial applications.Rate this question:
- 40.
What conditions are needed for the hydration of ethene?
Explanation
The hydration of ethene requires three conditions: a temperature of 300 degrees, a pressure of 60-70 atm, and the presence of a phosphoric acid catalyst. These conditions promote the reaction between ethene and water, leading to the formation of ethanol. The high temperature and pressure help overcome the activation energy barrier, while the phosphoric acid catalyst acts as a facilitator, increasing the rate of the reaction.Rate this question:
- 41.
State 2 problems or difficulties about the hydration of ethene process.
Explanation
The hydration of ethene process has two main problems or difficulties. Firstly, only 5% of the ethene reacts at a time, which means that the reaction is not very efficient and a large amount of ethene is wasted. Secondly, high energy is required to maintain the conditions necessary for the reaction to occur. This can be costly and may contribute to environmental issues. Additionally, the process uses finite resources, which means that it is not sustainable in the long term.Rate this question:
- 42.
State two differences between fermentation and the hydration of ethene.
Explanation
The fermentation process is relatively slow compared to the hydration of ethene. Fermentation involves the breakdown of organic substances by microorganisms, which takes time to complete. On the other hand, the hydration of ethene is a chemical reaction that occurs rapidly in the presence of a catalyst.
In terms of purity, fermentation often produces impure products due to the presence of other by-products or contaminants. In contrast, the hydration of ethene typically yields a more pure product as it is a controlled chemical reaction with fewer chances of impurities.Rate this question:
- 43.
What are the conditions needed for the dehydration of ethanol?
Explanation
The conditions needed for the dehydration of ethanol are alumina catalyst and heat. The alumina catalyst acts as a catalyst, speeding up the reaction without being consumed in the process. Heat is required to provide the necessary energy for the reaction to occur. The dehydration of ethanol involves the removal of a water molecule from ethanol, resulting in the formation of ethylene gas. The presence of the alumina catalyst and the application of heat facilitate this reaction, allowing ethanol to be converted into ethylene.Rate this question:
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Mar 21, 2023Quiz Edited by
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Dec 29, 2011Quiz Created by
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