Quantitive Chemistry (C3)

Question 1

Relative Formula Mass

Answer 1

The mass of a compound molecule.

(All of the relative atomic masses added)

Question 2

Define Ar

Answer 2

Relative Atomic Mass

Question 3

Define Mr

Answer 3

Relative Formula Mass

Question 4

What is a mole?

Answer 4

Mole is the amount of a substance that contains Avogadro’s number of particles (6.02X10^23)
(symbol = n, unit = mol)

Question 5

Define Avogadro’s Constant

Answer 5

6.02X10^23

Used in molar calculations

Question 6

Calculation linking moles, mass and mr

Answer 6

Mass = Moles X Mr
(grams = mol X Mr)
(g=nm)

Question 7

Define Conservation of Mass

Answer 7

For any chemical reaction,
Mass can neither be destroyed nor created, this means there is the same number and types of atoms on either side of a reaction equation.
MASS IS NEVER LOST NOR GAINED

Question 8

When may mass before or after an experiment vary?

Answer 8

If a gas has escaped, the mass will be lower than at the beginning,
If the reactants have reacted with a gas in the air, the mass will be greater than the mass at the beginning.

Question 9

Define Limiting Reactants

Answer 9

When one reactant becomes completely used up before the others, the reaction will stop (or change). This reactant is limiting.

Question 10

What is the yield of a reaction?

Answer 10

Yield is the mass of the product produced

Question 11

What is theoretical yield?

Answer 11

When we calculate yield, our answer is theoretical as it will never actually be 100% of what you expected. It is always less.

Question 12

What is r.t.p.?

Answer 12

When an environment is at 20*C and 1 atm

r.t.p. = room temperature and pressure

Question 13

Calculation to work out Volume of a gas at r.t.p

Answer 13

Volume of gas= (Mass of gas / Mr of gas) X 24

Question 14

At r.t.p. how much does 1 mole of any gas occupy

Answer 14

24 dm^3

Question 15

Define Concentration

Answer 15

Concentration of the amount of a substance in a certain volume

Question 16

Calculating concentration

2 calculations

Answer 16

Concentration (g/dm^3) = mass of solute (g) / volume of solvent (dm^3)
Concentration (mol/dm^3) = number of moles of solute (mol) / volume of solvent (dm^3)

Question 17

Define Solute

Answer 17

Substance which dissolves in another

Question 18

Define Solvent

Answer 18

Liquid which dissolves a solid

Question 19

Define Solution

Answer 19

A solvent with a solute dissolved into it

Question 20

Calculation linking moles, concentration and volume

Answer 20

Number of moles = Concentration X Volume

mol = mol/dm^3 X dm^3

Question 21

3 linked formula triangles with moles

Answer 21

See Figure (3) Page 2 of Folder.

Question 22

Define Atom Economy

Answer 22

What percentage of the overall mass is desired (and what is waste)

Question 23

Atom Economy Equation

Answer 23

Atom economy = (mr of desired products/mr of all reactants) X 100

Question 24

Define Percentage Yield

Answer 24

How much you really get in a reaction if 100% is the maximum yield.

Question 25

Percentage Yield Equation

Answer 25

Percentage yield = (mass of product actually made / theoretical yield) X 100