Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Chemical Formulae, Equations and Calculations Part 1
19 practice questions
Practice questions
11–19 of 19
Question 11
3 marks · Normal
Answer and see the solution →A student has 21 g of magnesium chloride (MgCl2). Calculate the number of moles of MgCl2 present.
(Ar: Mg = 24, Cl = 35.5)
Question 12
3 marks · Normal
Answer and see the solution →The equation for a reaction is:
A student reacts 27.0 g of aluminium (Al) with 85.0 g of chlorine (Cl2). Using the information in the equation, explain how you would determine which reactant is in excess and calculate the maximum mass of aluminium chloride (AlCl3) that could be formed.
(Ar: Al = 27, Cl = 35.5)
Question 13
4 marks · Normal
Answer and see the solution →A compound contains 9.45 g potassium, 5.25 g phosphorus, and 12.80 g oxygen.
(Ar: K = 39, P = 31, O = 16)
(a)[2 marks]Calculate the number of moles of each element present in the sample.
(b)[2 marks]Determine the empirical formula of the compound.
Question 14
1 mark · Normal
Answer and check →Which of the following could be a method for determining the empirical formula of a metal oxide?
- A.Burning the metal in air and weighing the increase in mass
- B.Measuring the temperature before and after mixing with water
- C.Electrolysing the metal and collecting the gas
- D.Testing the metal with universal indicator
Question 15
2 marks · Normal
Answer and see the solution →Write the balanced chemical equation, with state symbols, for the reaction of calcium carbonate with dilute nitric acid to form calcium nitrate, carbon dioxide, and water.
Question 16
4 marks · Normal
Answer and see the solution →Answer the questions about calcium hydroxide, Ca(OH)2.
(a)[1 mark]State the relative atomic masses (Ar) for Ca, O, and H.
(b)[2 marks]Calculate the relative formula mass (Mr) of Ca(OH)2.
(c)[1 mark]What mass of Ca(OH)2 is present in 0.5 mol of the compound?
Question 17
2 marks · Hard
Answer and see the solution →The molecular formula of a hydrocarbon is found to be C6H12. State its empirical formula.
Question 18
5 marks · Hard
Answer and see the solution →An experiment is carried out to determine the formula of a hydrated salt, magnesium sulfate crystals, MgSO4·nH2O. The following results are obtained:
Measurement Mass / g Mass of empty crucible 28.60 Mass of crucible + hydrated salt before heating 30.88 Mass of crucible + salt after heating to constant mass (anhydrous MgSO4) 30.00 (Ar: Mg = 24, S = 32, O = 16, H = 1)
(a)[1 mark]Calculate the mass of water lost during heating.
(b)[2 marks]Calculate the number of moles of anhydrous magnesium sulfate (MgSO4) present after heating. (Show your working.)
(c)[2 marks]Determine the value of n in the formula MgSO4·nH2O. (Show your working.)
Question 19
2 marks · Hard
Answer and see the solution →Write the balanced chemical equation, including state symbols, for the reaction of solid sodium with water to form aqueous sodium hydroxide and hydrogen gas.