Amount of Substance

Question 1

Moles =

Answer 1

mass (g) / Mr
OR
grams / RAMS

Question 2

a + 3b –> 2x + 3y

🗸 ?

Answer 2

1. find moles of a
2. ans = 1 mol (it’s a 1:2 ratio a:x)
3. ans x 2 (to get 2mols of x)
4. mass of x = moles x mr
5. final ans 3sf

Question 3

4a + 3b –> 2x + 6y

🗸 ?

Answer 3

1. moles of a
2. ans = 4 mols (4:3 ratio a:b). 1 mol of a = 3/4 mols of b
3. ans x 3/4 = mols of b
4. mass of b = moles x mr
5. ans to 3sf

Question 4

how to calculate limiting reagents

Answer 4

1. compounds
2. moles at the start
3. change in moles

0 mol = limiting reagent
mol > 0 = excess

Question 5

in a limiting reagents calculation, a limiting agent has …. mols

Answer 5

0

Question 6

in a limiting reagents calculation, the compound in excess has…. mols

Answer 6

a number greater than 0

Question 7

in limiting reagents calculations you only consider the left/right of the equation

Answer 7

left