moles

Question 1

what does RFM = in moles

Answer 1

1 mole

Question 2

what does the mole triangle look like

Answer 2

mass
mole RFM
pretend this is a triangle

Question 3

how many moles are there in
50g of calcium
100g of magnesium
25g of copper

Answer 3

50/40 = 1.25
100/24 = 4.2
25/16 = 1.5625

Question 4

whats a limiting reactant

Answer 4

the reactant that is all used up

Question 5

if a mass is giving in kg what do you do

Answer 5

change it to grams before converting to moles. 1 kg = 1000 g and 1 tonne = 1 000 000 g (1000 kg).

Question 6

Calculate the mass of iron formed when 2.55 g of iron(III) oxide reacts with an excess of carbon
according to the equation. Give your answer to 2 decimal places.

2Fe₂O₃ + 3C → 4Fe + 3CO₂

Answer 6

Moles of Fe formed = 0.01594 × 2 = 0.03188
Mass of Fe formed = 0.03188 × 56 = 1.79 g

Question 7

Calculate the mass of potassium sulfide formed when 20.0 g of potassium are mixed with

20.0 g of sulfur and the reaction allowed to occur.

Answer 7

Moles of K₂S = 0.5128
2
= 0.2564 (as ratio of K:K₂S = 2:1).
Mass of K₂S = 0.2564 × 110 = 28.2