C3 - Quantitative Chemistry

Question 1

Avogadros Constant

Answer 1

6.022 x10^23

Question 2

Equation for moles

Answer 2

Mass
Moles= ———————
Mr

Question 3

Equation for concentration

Answer 3

Moles/mass
Concentration = ——————
Volume

Question 4

Cm cubed to dm cubed

Answer 4

Divide by 1000

Question 5

How,to calculate percentage yield

Answer 5

Actual yield
Percentage yield = ———————————————————- X 100
Theoretical yield

Question 6

How to calculate atom economy

Answer 6

RAM of desired product
Atom economy = ———————————————— x 100
total RAM of reactants

Question 7

What is the volume of 1 mole of any gas at room temperature?

Answer 7

24 dm3

Question 8

How to calculate the volume of a gas

Answer 8

Amount In moles × molar volume (24)

Question 9

Number of moles x 24 = ….

Answer 9

Volume (dm3)

Question 10

What does conservation of mass mean

Answer 10

no atoms are lost or made during a chemical reaction so the mass of the products equals the mass of the reactants.

Question 11

What is the relative formula mass of a substance? (Mr)

Answer 11

The sum of the relative atomic masses of the atoms in a given formula

Question 12

What is uncertainty

Answer 12

For a thermometer with a mark at every 1.0°C, the uncertainty is ± 0.5°C. The range of possible answers

Question 13

What are moles and what is the unit for them?

Answer 13

Chemical amounts are measured in moles. The symbol for the unit mole is mol.

Question 14

How to calculate the masses of substances in a balanced symbol equation

Answer 14

mass = relative formula mass × amount
Eg. O2 = 16 * 2

Question 15

What is the limiting reagent in a chemical reaction

Answer 15

The reactant that is completely used up is called the limiting reactant because it limits the amount of products that can be made

Question 16

How to calculate the relative atomic mass of an atom

Answer 16

1. Identify isotopes present in the mixture or environment, and the abundance of each isotope of the element.
2. Identify the mass number. For each isotope of the element.
3. Do abundance times mass number for 1 isotope. Add the abundance times the mass number of the other isotope and divide by total % abundance (usually 100)

Question 17

How can the concentration of a solution be changed (2 ways)

Answer 17

concentration can be increased by dissolving more solute in a given volume of solution - this increases the mass of the solute
concentration can be increased by allowing some of the solvent to evaporate - this decreases the volume of the solution

Question 18

What is atom economy

Answer 18

measure of the amount of starting materials that end up as useful products.

Question 19

What is the percentage yield?

Answer 19

A measure of how much product is actually made

Question 20

explain how the concentration of a solution in mol/dm3 is related to the mass of the solute and the volume of the solution

Answer 20

The higher the mass of the solute in comparison to the volume of the solution, the higher the concentration