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Chemistry AQA GCSE:
Calculations 1a

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).

1. Calculate the relative formula mass (Mr) of calcium hydroxide, Ca(OH)2.
  • A.   38
  • B.   58
  • C.   74
  • D.   114
2. Which of the following contains the greatest number of moles?
  • A.   2.4 g of carbon, C
  • B.   2.3 g of sodium, Na
  • C.   2.4 g of Magnesium, Mg
  • D.   3.9 g of potassium, K
3. A student required 0.15 moles of magnesium oxide, MgO, for a reaction. What mass of MgO should she weigh out? [Mr of MgO is 40]
  • A.   0.00375 g
  • B.   0.0060 g
  • C    6.0 g
  • D.   267 g
4. Which of the following statements about chemical reactions is true?

The total mass of the reactants is ...

  • A.  .. equal to the total mass of the products in all chemical reactions
  • B.   ..less than the total mass of the products in a precipitation reaction in a closed flask
  • C.   ..is greater than the total mass of the products in a precipitation reaction in a closed flask
  • D.  .. is greater than the total mass of the products in a reaction producing a gas in an open flask
5. 60.0g of calcium carbonate decomposed on heating to form calcium oxide and carbon dioxide.   The equation for the reaction is:

                                            CaCO3  CaO + CO2

What is the maximum mass of calcium oxide which could be formed in this reaction?
[Mr values: CaCO3 = 100; CaO = 56; CO2 = 44]

  • A.   26.4 g
  • B.   30.0 g
  • C.   33.6 g
  • D.   56.0 g
6. A thermometer has a scale mark at every 0.5°C. What is the best estimate of the uncertainty of any temperature readings made using this thermometer?
  • A.   ±0.1°C
  • B.   ±0.25°C
  • C.   ±0.5°C
  • D.   ±1°C
7. A student recorded the time taken for a piece of magnesium to disappear in acid. For reliability, he repeated his experiment 5 times and obtained the following results:

42.0s, 44.0s, 43.5s, 43.0s, 42.5s
What is the mean value and best estimate of the uncertainty for this set of readings?

  • A.   43.0 ± 0.25 s
  • B.   43.0 ± 0.5 s
  • C.   43.0 ± 1.0 s
  • D.   43.5 ± 0.1 s
8. 1.38 g of sodium was burned in oxygen. An oxide of mass 2.34 g was formed.

Calculate the moles of sodium and oxygen atoms in the final product.
[Ar of Na = 23; Ar of O = 16]

  Moles of sodium atoms Moles of oxygen atoms
A 0.06 0.146
B 0.06 0.06
C 0.102 0.06
D 0.102 0.146

Q9-10: 34.0 kg of ammonia, NH3 is reacted with excess nitric acid, HNO3, to produce ammonium nitrate fertilizer. The equation for the reaction is:

NH3  + HNO3  NH4NO3

 

fertilizer

Muibu88 | CC4.0 licence

9. Calculate the number of moles of ammonia, NH3, used in this reaction.

[Relative atomic masses H = 1; N = 14, O = 16]

  • A.   2.27
  • B.   2.00
  • C.   2267
  • D.   2000
10. Calculate the maximum mass, in kg, of ammonium nitrate formed [Mr of NH4NO3 is 80]
  • A.   181.6 kg
  • B.   160 kg
  • C.   181,600 kg
  • D.   160,000 kg