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Chemistry Edexcel iGCSE:
Calculations 1b

For Double and Triple sciences

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Grab a calculator and a copy of the periodic table

(This test has only 10 questions, but may take 15 - 20 mins).

Q1-3:  A student used the following reaction to try to produce 20.0 g of copper(II)chloride.

CuCO3 + 2HCl  CuCl2  + H2O  + CO2

[Relative atomic masses Cl = 35.5; Cu = 63.5]

 

1. The formula mass of copper(II)chloride and the number of moles of copper(II)chloride produced is …

  Formula Mass Moles produced
A 99 4.95
B 99 0.202
C 134.5 6.73
D 134.5 0.149
2. What mass of copper(II)carbonate does the student need to react with excess hydrochloric acid to make the 20.0 g of copper(II)chloride? [Mr of CuCO3 = 123.5]
  • A.   18.4 g
  • B.   20.0 g
  • C.   24.9 g
  • D.   36.8 g
3. If the percentage yield of copper(II)chloride in this reaction was only 72% what mass of copper(II)chloride did the student actually produce?
  • A.   7.2 g
  • B.   14.4 g
  • C.   27.8 g
  • D.   1440 g

4. In the thermite reaction aluminium powder reacts very exothermically with iron(III)oxide displacing molten iron. The equation for the reaction is: 

2Al + Fe2O3  Al2O3 + 2Fe

What mass of molten iron is formed from 0.1moles of iron(III)oxide?
[Mr of Fe2O3 is 160; Ar of Fe is 56]

thermite reaction
Author:Caesium Fluoride | CC 3.0
  • A.   2.8 g
  • B.   5.6 g
  • C.   11.2 g
  • D.   22.4 g

Q5-7:
1.23 g of hydrated magnesium sulfate, MgSO4.xH2O, was heated to constant mass in a crucible.
0.60 g of anhydrous magnesium sulfate, MgSO4, remained at the end.
[Relative formula masses: MgSO4 = 120; H2O = 18]

 
5. Calculate the number of moles of anhydrous magnesium sulfate produced.
  • A: 0.0050
  • B: 0.010
  • C: 0.50
  • D: 2.0
6. Calculate the number of moles of water released.
  • A: 0.033
  • B: 0.035
  • C: 0.068
  • D: 0.050

7. Determine the value of ‘x’ in the MgSO4.xH2O

 

8. A mass of 3 g of magnesium was reacted with 0.200 moles of ethanoic acid in the following reaction:

Mg + 2CH3COOH  (CH3COO)2Mg + H2

Calculate the number of moles of magnesium used and determine the reagent in excess.

  Number of moles of magnesium Reagent in excess
A 0.125 Ethanoic acid
B 0.125 magnesium
C 0.1 Ethanoic acid
D 0.1 magnesium
9. An ore of titanium contains 36.8% iron, 31.6% titanium and 31.6% oxygen.

Determine the simplest whole number ratio for the moles of atoms.
[Ar values: Fe = 56; Ti = 48; O = 16]

  Fe Ti O
A 1 1 1
B 1 1 2
C 1 1 3
D 4 3 1
10. Iron(III)hydroxide is a brown precipitate formed during the test for iron(III) ions.

FeCl3 (aq)  + 3NaOH (aq)  Fe(OH)3 (s)   +   3NaCl (aq)

What amount, in moles, of each reactant would be needed to produce 0.6 moles of iron(III)hydroxide?

 
  Moles of FeCl3 (aq) Moles of NaOH (aq)
A 0.2 0.6
B 0.3 0.3
C 0.6 0.6
D 0.6 1.8