Define The Following Terms Of Chemistry Quiz

1. What are atoms?

-Building blocks of matter
Made of 3 types of particles1. Protons in nucleus (+ charge)2. Neutrons in nucleus (neutral charge)3. Electrons around nucleus (negative charge)

Atoms are the smallest unit of energy.

Atoms cannot be found in nature.

Atoms consist only of protons in the nucleus.

Atoms are the basic units of matter, consisting of protons, neutrons, and electrons. They are essential building blocks of all substances in the universe.

Explanation

Atoms are the basic units of matter, consisting of protons, neutrons, and electrons. They are essential building blocks of all substances in the universe.

2. What is the role of a proton in an atom?

Has a negative charge and repels electrons

Has positive charge combines with neutron to make most of atomic mass

Combines with electrons to form chemical bonds

Has a neutral charge and helps stabilize the nucleus

Protons have a positive charge and are found in the nucleus of an atom. They combine with neutrons to make up most of the atomic mass of an atom, contributing to its stability and identity.

Explanation

Protons have a positive charge and are found in the nucleus of an atom. They combine with neutrons to make up most of the atomic mass of an atom, contributing to its stability and identity.

3. What is a solution?

A solid substance dissolved in a liquid.

A mixture where one substance is visibly separated from the others.

A gaseous mixture of different elements.

Homogeneous mixture of 2 or more substances

A solution is a type of mixture where two or more substances are mixed together evenly. It is considered homogeneous because the various components are uniformly distributed throughout the mixture.

Explanation

A solution is a type of mixture where two or more substances are mixed together evenly. It is considered homogeneous because the various components are uniformly distributed throughout the mixture.

4. What is a solute?

The substance doing the dissolving

The substance being dissolved (usually a solid)

The liquid in which the dissolution occurs

The temperature at which the dissolution happens

A solute refers to the substance that is being dissolved in a solution, usually in the form of a solid. It is different from the solvent, which is the liquid in which the solute dissolves. The temperature does play a role in the rate of dissolution, but it is not the definition of a solute.

Explanation

A solute refers to the substance that is being dissolved in a solution, usually in the form of a solid. It is different from the solvent, which is the liquid in which the solute dissolves. The temperature does play a role in the rate of dissolution, but it is not the definition of a solute.

5. What is a solvent?

The process of solidifying a liquid.

A type of chemical reaction involving heat.

The substance being dissolved (solid or gas).

The substance doing the dissolving (usually a liquid)

A solvent is the substance that does the dissolving, usually a liquid, in a solution. It is different from the solute, which is the substance being dissolved.

Explanation

A solvent is the substance that does the dissolving, usually a liquid, in a solution. It is different from the solute, which is the substance being dissolved.

6. What is the formula for Molarity?

The sum of moles of solute and solvent divided by the volume of the solution

# moles of solute in one Litre of a solution
(aka M)
note: the volume must always be in liters when calculating molarity
OR:

Moles of solute divided by the volume of the solvent

The volume of the solvent squared

Molarity is calculated by dividing the number of moles of solute by the volume of the solution in liters. It is important to remember that the volume must always be in liters when calculating molarity.

Explanation

Molarity is calculated by dividing the number of moles of solute by the volume of the solution in liters. It is important to remember that the volume must always be in liters when calculating molarity.

7. When 2 solutions mix, the volumes may not be ________. Give an example of what ____ means.

Combined.

Additive. i.e. while mixing two 50mL solutions, the final solution might not be a total of 100mL

Equal.

Consistent.

When two solutions mix, the resulting volume is not always simply the sum of the individual volumes, which is known as additivity.

Explanation

When two solutions mix, the resulting volume is not always simply the sum of the individual volumes, which is known as additivity.

8. When diluting a solution, the number of moles of the solvent DOES/DOESN'T change. Formula.

The process of reducing concentration of a solution either by adding a solute or another solvent. The # moles of the solvent DOES NOT change when diluting a substance(as long as a reaction doesn't take place)

The number of moles of the solvent INCREASES when diluting a substance.

The number of moles of the solvent DECREASES when diluting a substance.

The number of moles of the solvent changes depending on the size of the container used for dilution.

9. What is the formula for density?

The mass of a unit of volume of the solution

The weight of a unit of volume of the substance.

The volume of a unit of mass of the substance.

The amount of matter in a substance.

Density is calculated by dividing the mass of a substance by its volume. It is a measure of how much mass is contained in a given volume of a substance.

Explanation

Density is calculated by dividing the mass of a substance by its volume. It is a measure of how much mass is contained in a given volume of a substance.

10. What is the correct formula for Parts per Million (ppm) and Parts per Billion (ppb)?

Ppm- The ratio of volume of a solute to the volume of solution expressed in different units and multiplied by 10^6ppb- The ratio of volume of a solute to the volume of solution expressed in different units and multiplied by 10^9

Ppm- The ratio of mass of a solute to the mass of solution expressed in the same units and multiplied by 106

ppb- The ratio of mass of a solute to the mass of solution expressed in the same units and multiplied by 109

Ppm- The ratio of moles of a solute to the moles of solution expressed in the same units and multiplied by 10^6ppb- The ratio of moles of a solute to the moles of solution expressed in the same units and multiplied by 10^9

Ppm- The ratio of mass of a solute to the mass of solution expressed in different units and multiplied by 10^6ppb- The ratio of mass of a solute to the mass of solvent expressed in the same units and multiplied by 10^9

Parts per Million (ppm) and Parts per Billion (ppb) are measures used to represent the concentration of a substance in a solution. ppm is used when the concentration is very low (in parts per million), while ppb is used when the concentration is even lower (in parts per billion). The correct formula involves the ratio of mass of solute to mass of solution, not volume or moles. The multiplication by 10^6 for ppm and 10^9 for ppb ensures the correct representation of the concentration.

Explanation

Parts per Million (ppm) and Parts per Billion (ppb) are measures used to represent the concentration of a substance in a solution. ppm is used when the concentration is very low (in parts per million), while ppb is used when the concentration is even lower (in parts per billion). The correct formula involves the ratio of mass of solute to mass of solution, not volume or moles. The multiplication by 10^6 for ppm and 10^9 for ppb ensures the correct representation of the concentration.

11. What is the molarity of 350 mL solution which contains 25.00g CuSO4?

C. Find the MM of CuSO4. MM = 250.00 g/mol. Use this MM to calculate the molarity of the solution directly.

B. Divide the mass of CuSO4 (25.00g) by the volume in liters (0.350 L) to get the molarity.

A. Multiply the volume in liters (0.350 L) by the number of moles (2.50 mol) to get the molarity.

1. Find the MM of CuSO4
MM=249.17 g mol -1

2. calculate n (number of moles per CuSO4)

3. Now answer the question by calculating the molarity of the solution:

To find the molarity of a solution, you need to first calculate the number of moles of solute present. Once you have the number of moles, you can divide it by the volume of the solution in liters to get the molarity. Incorrect answers a, b, and c do not follow this correct approach.

Explanation

To find the molarity of a solution, you need to first calculate the number of moles of solute present. Once you have the number of moles, you can divide it by the volume of the solution in liters to get the molarity. Incorrect answers a, b, and c do not follow this correct approach.

12. A solution of HCl has a concentration of 1.258 mol/L. What volume of this solution contains 0.258 mol of HCl?

Therefore, 250 mL of solution contains 0.258 mol HCl.

Therefore 205 mL of solution contains .258 mol HCl

Therefore, 155 mL of solution contains 0.258 mol HCl.

Therefore, 305 mL of solution contains 0.258 mol HCl.

The correct answer can be calculated using the formula: Volume (mL) = Number of moles / Concentration (mol/L). In this case, Volume (mL) = 0.258 mol / 1.258 mol/L = 205 mL.

Explanation

The correct answer can be calculated using the formula: Volume (mL) = Number of moles / Concentration (mol/L). In this case, Volume (mL) = 0.258 mol / 1.258 mol/L = 205 mL.

13. When comparing the molarities of starting and diluted solutions, what useful relation can be used?

The amount of solute before dilution decreases.

The amount of solute after dilution increases.

note: this expression explains the fact that the amount of solute before and after dilution with a solvent (or another nonreactive substance) is the same

The amount of solute after dilution decreases.

The correct answer pertains to the law of conservation of mass, stating that the total amount of solute remains constant regardless of dilution.

Explanation

The correct answer pertains to the law of conservation of mass, stating that the total amount of solute remains constant regardless of dilution.

14. How well are you going to do on this midterm??

SOOO well!! Keep up the great work. It'll be worth it

I'm expecting to fail miserably.

I don't care about the outcome, so probably not well.

Not too good, I haven't studied much.

The correct answer provides positive reinforcement and encourages the individual to continue working hard and remain optimistic about their performance on the midterm.

Explanation

The correct answer provides positive reinforcement and encourages the individual to continue working hard and remain optimistic about their performance on the midterm.

15. Some more info on density: 1. expressed in ______ 2. although there are at least ___ components to each solution....

1. expressed in g/mL
2. although there are at least 2 components to each solution, the density of the solution always refers to the ENTIRE solution, not just its components.

1. expressed in kg

3. expressed in mol/L

2. although there are at least 3 components to each solution...

Density is typically expressed in g/mL and refers to the entire solution, not just individual components within it.

Explanation

Density is typically expressed in g/mL and refers to the entire solution, not just individual components within it.

16. An aqueous solution that contains 70.0% HNO3 by mass has a density of 1.42g mL-1a) What is the volume of the 100g of the nitric acid solution?b) calculate the molarity from info calculated in a (3 steps).

-"70.0% of HNO3 by mass" therefore in a 100.0g solution, 70.0 g would be HNO3 and 30.0g water.
-the density of the solution is 1.42 g mL ,', 1.00 mL has a mass of 1.42 g
a)

b)we know 70.0g of 100.0 g solution is HNO3 so we can now calculate the MM and ultimately n:
MM=63.018g mol-1

Therefore, 1.1108 mol of nitric acid are contained in 70.42 mL of solution and...

50.0% of HNO3 by mass; therefore in a 100.0g solution, 50.0 g would be HNO3 and 50.0g water.

The density of the solution is 2.0 g mL-1, 1.00 mL has a mass of 1.50 g.

In a 100.0g solution, 30.0g would be HNO3 and 70.0g water.

17. What is the ppm of CuSO4 prepared from 0.200g Copper Sulfate and 350 mL of water? Assume water's density is 1.00g/mL. If you were calculating ppb, how would the formula be different?

The ppm calculation would be the same for ppb, just the unit would change.

The ratio for ppb would be divided by 10^6 instead of multiplied by 10^9.

Using the dentisy of water, the mass of water would be 350 g ,', the total mass of the solution would be mass of water + copper sulfate:

350g + .200 g= 350.2g is mass of solution

Therefore:

note: if calculating ppb the ratio would be multiplied by 109 rather than 106

The ppm calculation can be directly converted to ppb without any multiplication.

When converting from ppm to ppb, you need to consider the difference in the multiplier - ppm uses 10^6 while ppb uses 10^9. This is to account for the different orders of magnitude between parts per million and parts per billion.

Explanation

When converting from ppm to ppb, you need to consider the difference in the multiplier - ppm uses 10^6 while ppb uses 10^9. This is to account for the different orders of magnitude between parts per million and parts per billion.

18. What are some properties of neutrons?

2. exist outside the nucleus

3. make up the majority of an atom's charge

1. are electronically neutral (have no charge)

2. combine with protons to make most of the atom's mass

3. is inside the nucleus with Protons

1. carry a positive charge

19. What are some characteristics of electrons?

Is heavier than the entire atom

1. has a negative charge
2. is only 1/1836th of the atom's mass
3. orbits the nucleus
4. Can be represented as dots or waves depending on what theory you're going with.

Has a positive charge

Does not orbit the nucleus

Electrons have a negative charge, are much lighter than the atom, and orbit the nucleus. They can also be understood as particles or waves based on different theories.

Explanation

Electrons have a negative charge, are much lighter than the atom, and orbit the nucleus. They can also be understood as particles or waves based on different theories.

20. What does the atomic number represent?

Number of neutrons in the nucleus.

Number of electrons in the outermost shell.

Total mass of the atom.

Number of protons (and electrons) in the nucleus (Z)

The atomic number of an element is equal to the number of protons (and electrons) in its nucleus. It determines the element's identity and its position on the periodic table.

Explanation

The atomic number of an element is equal to the number of protons (and electrons) in its nucleus. It determines the element's identity and its position on the periodic table.

21. What does the mass number notation (A) represent in an atom?

The number of isotopes present in the nucleus

The total number of electrons and protons in the nucleus

# of Protons and Neutrons in the nucleus/atom in general
(A)

Notation number 1:
i.e. Helium
A=Mass #Z= Atomic #
X= Chemical symbol

Notation number 2:
i.e. Sodium Na-23
i.e. Carbon C-12

The number of electrons orbiting the nucleus

The mass number notation (A) represents the total number of protons and neutrons in the nucleus of an atom, not the number of electrons, total electrons and protons, or the number of isotopes.

Explanation

The mass number notation (A) represents the total number of protons and neutrons in the nucleus of an atom, not the number of electrons, total electrons and protons, or the number of isotopes.

22. What is Atomic Mass?

The number of protons in an atom

Physical Mass of an atom expressed in g, Kg etc.

Amu is the chemical unit of atoms also known as Dalton (Da or )
i.e. One atomic mass unit of Carbon is 1/12 Da

The number of neutrons in an atom

The total number of electrons in an atom

Atomic Mass refers to the mass of an atom, not the number of particles within it such as protons, neutrons, or electrons.

Explanation

Atomic Mass refers to the mass of an atom, not the number of particles within it such as protons, neutrons, or electrons.

23. IsotopesTherefore would have the _______ atomic # and _______mass #.examples with Carbon and Chlorine isotopes.

Atoms with the same number of protons but a different number of neutrons (usually more)

Therefore would have the SAME atomic # and DIFFERENT mass #.

A (mass #) for carbon is 12 (6 P+ and 6 No) ,', C-12C-14 is a heavier isotope with 6 P+ and 8 N0

Cl-34 has 2 stable isotopes:
Cl-35 (17 P+ and 18 N0)
Cl-37 (17 P+ and 20 N0)

DIFFERENT atomic # and SAME mass #

SAME atomic # and SAME mass #

DIFFERENT atomic # and DIFFERENT mass #

Isotopes have the same atomic number but different mass numbers due to variations in the number of neutrons present in the nucleus.

Explanation

Isotopes have the same atomic number but different mass numbers due to variations in the number of neutrons present in the nucleus.

24. Isotopic abundance affects the average atomic mass in what way?

Energy level of each isotope

Ratio of protons to neutrons in each isotope

Number of electrons in each isotope

% by # of each isotopic abundance (Sometimes there is an abundance of one isotope; sometimes it's extremely rare)
i.e. 3 stable isotopes for silicon
Si-28 (92.23%), Si-29 (4.67%) and Si-30 (3.10%)

,', in any sample of Silicon would be one of those 3 but Si-28 is the most naturally occurring
________________________________

Isotopic abundance refers to the different percentages by the number of each isotope present in a sample, which in turn affects the average atomic mass by weighting the contribution of each isotope according to its abundance.

Explanation

Isotopic abundance refers to the different percentages by the number of each isotope present in a sample, which in turn affects the average atomic mass by weighting the contribution of each isotope according to its abundance.

25. What is mass defect?

Mass defect is the difference between the mass of an object and the gravitational force acting on it.

When protons and neutrons are combined in the nucleus, some energy is needed therefore some if its total mass is lost.

The mass of an object is its weight.

Mass defect refers to the increase in mass when protons and neutrons combine in the nucleus.

Mass defect refers to the difference between the total mass of individual protons and neutrons and the actual mass of the nucleus when they are combined. This difference in mass is converted into energy according to Einstein's famous equation E=mc^2.

Explanation

Mass defect refers to the difference between the total mass of individual protons and neutrons and the actual mass of the nucleus when they are combined. This difference in mass is converted into energy according to Einstein's famous equation E=mc^2.

26. What is the collective term used for atoms/groups of atoms that have gained or lost electrons?

Elements

Isotopes

Collective term used for atoms/groups of atoms that have gained/lost electrons C--an atom that loses 1 or more electrons and gets a positive charge ,', becoming a Cation A-- an atom that gains 1 or more electrons and gets a negative charge ,', becoming an Anion

Molecules

Ions refer to atoms or groups of atoms that have an electric charge due to the loss or gain of electrons. Isotopes are atoms of the same element with different numbers of neutrons, molecules are combinations of atoms held together by chemical bonds, and elements are pure substances made of only one type of atom.

Explanation

Ions refer to atoms or groups of atoms that have an electric charge due to the loss or gain of electrons. Isotopes are atoms of the same element with different numbers of neutrons, molecules are combinations of atoms held together by chemical bonds, and elements are pure substances made of only one type of atom.

27. What are molecular/complex ions?

Ions originated from ionic compounds

Ions formed by single atoms

Ions derived from isotopes

Ions of molecules

Nitric acid cation

HNO3+

Molecular/complex ions refer to ions of molecules like the nitric acid cation HNO3+, which are formed by groups of atoms with an overall charge.

Explanation

Molecular/complex ions refer to ions of molecules like the nitric acid cation HNO3+, which are formed by groups of atoms with an overall charge.

28. What is a compound?

A substance that cannot be broken down into simpler substances by chemical means.

A molecule composed of a single element.

A substance that is made up of only one type of atom.

Is a molecule containing atoms of more than one element

i.e. H2O is a compound but O2 isn't

A compound consists of different types of atoms bonded together, whereas the other incorrect answers refer to elements or substances that are not compounds.

Explanation

A compound consists of different types of atoms bonded together, whereas the other incorrect answers refer to elements or substances that are not compounds.

29. What is a mole? (4 examples)

The amount of atoms/molecules in a sample of a substance is expressed in moles

(n= # of moles)

i.e. 1 mole is the number of atoms in 12g of Carbon

i.e. 1 mole Silicon is 6.02x1023 Si atoms
1mole glucose is 6.02x1023 C6H12O6 molecules
1 mole nitrate is 6.02x1023 NO3- ions

The weight of a substance in grams

The temperature at which a substance melts

The color of a substance under UV light

A mole is a unit used in chemistry to represent a certain amount of substance, specifically the number of atoms or molecules.

Explanation

A mole is a unit used in chemistry to represent a certain amount of substance, specifically the number of atoms or molecules.