Paper 1: Quantative Chem

Question 1

Relative formula masses

Answer 1

Add up all of the relative formula masses in the compound (Ar)
Eg: Find the rfm of MgCl2
Ar mg=24 Cl=35.5

= 24+(2x35.5) = 95

Question 2

% Mass of an element in a compound

Answer 2

= Ar x no of atoms of that element
————————
Mr of the compound

All x100

Question 3

What is the value of the mole?

Answer 3

6.02 x 10^23

Question 4

Moles Equation

Answer 4

Grams
Moles = ————
Mr

Question 5

Conservation of mass

Answer 5

Add up Rf on both sides, they will be the same

Question 6

Reacting masses ->

Balanced symbol eqs

Answer 6

1) divide mass of each substance by rfm (=moles)
2) divide moles by smallest mole value in reaction
3) if any decimals, times all up to reach all whole numbers
4) put the numbers on the eq

Question 7

Calculating masses

Answer 7

1) balances symbol eq
2) Rf of what u want
3) no of moles of substance u know
4) use ration to fine no of moles in what u want
5) use moles to calculate grams
(m=g/mr)

Question 8

Volume of gas

Answer 8

(Mass of gas/mr of gas) x 24

Question 9

Concentration

Answer 9

= no moles in solute/vol of solvent

= mass of solute/vol of solvent

Question 10

Titration Calculation

Answer 10

C1V1 C2V2
——— = ———
N1 N2

Question 11

Mol/dm3 to g/dm3

Answer 11

1) work out rfm for acid

2) times conc by rfm

Question 12

Atom economy

Answer 12

(Rfm of desired product/rfm of all reactants)

X100

Question 13

Percentage yield

Answer 13

(Mass of product actually made/maximum theoretical mass of product)

X100

Question 14

Empirical Formula

Answer 14

E - Element
M - Mass
M - Moles (use mass/mr)
R - Ratio