Amount of Substance

Question 1

What is relative atomic mass?

Answer 1

Weighted mean mass of an atom relative to 1/12th the mass of one atom of carbon 12

Question 2

What involves relative formula mass?

Answer 2

Giant ionic
Giant covalent
Giant metallic

Question 3

What involves relative molecular mass?

Answer 3

Simple molecular

Question 4

What is the percentage by mass equation?

Answer 4

No.of atoms X relative matomic mass of element
————————————————————————-X100
Mr of compound

Question 5

What is the equation for atom economy?

Answer 5

Mr of desired product
——————————-X100
Mr of all products

Question 6

What must you include when doing atom economy?

Answer 6

The big numbers in the equation

Question 7

What is the equation for percentage yield?

Answer 7

Actual yield
—————–X100
Theoretical yield

Question 8

How do you calculate percentage yield?

Answer 8

Calc the Mr of reactant not in excess + Mr of product
If doesn’t tell you one in excess calc all
Calc no. of moles
Lowest value = limiting reagent

Question 9

How do you calculate concentration?

Answer 9

Vol

Question 10

What is the equation for no. of moles?

Answer 10

Mr

Question 11

What is the equation for no. of moles in a gas?

Answer 11

24

Question 12

What is the ideal gas equation?

Answer 12

pv = nRT

Question 13

What must be the units of volume be in IGE?

Answer 13

M3

Question 14

What must be the units of pressure be in IGE?

Answer 14

Pa

Question 15

What must be the units of temperature be in IGE?

Answer 15

K

Question 16

What must be the units of gas content be in IGE?

Answer 16

J/mol/K

Question 17

How do you get from cm3 to m3?

Answer 17

X10-6

Question 18

How do you get from dm3 to m3?

Answer 18

X10-3

Question 19

How do you get from degrees to K?

Answer 19

+273

Question 20

How do you get from kPa to Pa?

Answer 20

X10 3

Question 21

What units must you always give vol if you’re finding it with the ideal gas equation?

Answer 21

Dm3

Question 22

How do you calculate water of crystallisation?

Answer 22

Find no. of moles of water lost (minus two masses)
Find moles of anhydrous salt
Now work out ration (big/small)

Question 23

How do you calculate the empirical formula?

Answer 23

Mass/Mr
Both answers divided by smallest value
To find the ratio

Question 24

What is the equation for no.of atoms?

Answer 24

No.of moles X 6.02 X1O 23

Question 25

When working out the no. of atoms in an compound, what must you do?

Answer 25

Multiply your answer by the no.of elements

Question 26

When working out the no. of molecules in an compound, what must you do?

Answer 26

Not multiply your answer by the no. of elements

Question 27

How do you calculate reacting masses?

Answer 27

Calc moles of compound Then find moles of mass you want to calc Moles X Mr = mass

Question 28

How do you calculate molecular formula from empirical?

Answer 28

Do mass/ Mr of empirical formula | Then multiply every element by your answer

Question 29

What is empirical formula?

Answer 29

The smallest whole number ration of atoms of each element in a compound

Question 30

What is molecular formula?

Answer 30

The actual number of atoms of each element in a molecule

Question 31

What is atom economy?

Answer 31

A measure of the proportion of reactant atoms that become part of the desired product in the balanced chemical equation

Question 32

What is the theoretical yield?

Answer 32

The mass of the product that should be formed if no chemicals are lost in the process

Question 33

What should the actual yield always be?

Answer 33

Less than the theoretical