OCR Gateway GCSE Chemistry

Topic Questions

3.1 Introducing Chemical Reactions

11 mark

A student reacts calcium carbonate with hydrochloric acid.

CaCO3(s) + 2HCl(aq) →CaCl2(aq) + H2O(l) + CO2(g)

What physical state does (g) represent in the balanced symbol equation?

  • Aqueous

  • Gas

  • Liquid

  • Solid

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21 mark

Look at the balanced symbol equation.


CaCO3 (s) + 2HCl (aq) → CaCl2 (aq) + H2O (l) + CO2 (g)


What does the symbol (s) represent in the balanced symbol equation?

  • Solid

  • Solute

  • Solution

  • Substance

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31 mark

The symbol of an aluminium ion is Al3+.

The symbol of an oxide ion is O2−.

What is the formula of aluminium oxide?

  • AlO

  • Al2O

  • Al3O2

  • Al2O3

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1
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1 mark

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Avogadro’s constant has a value of 6.02 × 1023.

How many oxygen atoms are in 0.25 moles of oxygen molecules?

  • 1.204 × 1024

  • 1.505 × 1023

  • 3.010 × 1023

  • 6.020 × 1023

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2
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Avogadro’s constant has a value of 6.02 × 1023.

What is the number of atoms in 0.5 mol of water?

  • 2.00 × 1023

  • 3.01 × 1023

  • 6.02 × 1023

  • 9.03 × 1023

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3
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1 mark

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Methane burns in oxygen to form carbon dioxide and water.

CH4 + 2O2 → CO2 + 2H2O

Calculate the amount of carbon dioxide made when 6.4 g of methane is burnt.

  • 2.8 g

  • 4.4 g

  • 14.4 g

  • 17.6 g

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4
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1 mark

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Sodium hydroxide reacts with hydrochloric acid. Sodium chloride and water are made.

NaOH + HCl → NaCl + H2O

What mass of sodium hydroxide would be needed to make 46.8 g of sodium chloride?

  • 16 g

  • 32 g

  • 50 g

  • 64 g

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51 mark

Phosphoric acid contains phosphate ions, PO subscript 4 superscript 3 minus end superscript

Phosphoric acid is completely neutralised by sodium hydroxide.

What is the formula of the salt that is made?

  • Na2PO4

  • Na3PO4

  • Na(PO4)3

  • Na2(PO4)3

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11 mark

The formula of an iron(III) ion is Fe3+ and the formula of the sulfate ion is SO42-.

What is the formula of iron(III) sulfate?

  • Fe2SO4

  • Fe3(SO4)2

  • Fe2(SO4)3

  • (Fe)2(SO4)3

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21 mark

Avogadro's constant has a value of 6.02 x 1023.

How many hydrogen atoms are in 0.05 moles of hydrogen molecules?

  • 3.01 x 1022

  • 3.01 x 1023

  • 6.02 x 1022

  • 6.02 x 1024

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31 mark

Which equation shows the formation of a Group 5 non-metal ion?

X represents a Group 5 non-metal and e- represents an electron.

  • X + e- → X-

  • X + 3e- → X3-

  • X  → X3-+ 3e-

  • X + 5e- → X5-

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41 mark

A piece of iron wool is left in moist air and goes rusty.

Which graph shows how the mass of the iron wool changes?

3-1_q4-ocr-gcse-chemistry-mcq

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5
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1 mark

A student wanted to make 15.0 g of zinc chloride. The equation for the reaction is:

ZnCO3 + 2HCl →  ZnCl2 + CO2 + H2O

What mass of zinc carbonate should the student add to the hydrochloric acid to make 15.0 g of zinc chloride?

Relative atomic masses (Ar): C = 12    Zn = 65   O= 16    Cl = 35.5     H= 1

  • 11.0 g

  • 13.8 g

  • 15.0 g

  • 22.0 g

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61 mark

Symbol equations always need to have the same number of atoms on both sides.

Which equation is correctly balanced?

  • H2SO4   +   2NaOH    →   Na2SO4   +   H2O

  • Ca(OH)2   +   2HCl    →    CaCl2   +   H2

  • 4Na   +   O­2­    →   2Na­2­O

  • 2Cu   +   8HNO3     →      2Cu(NO3)2  + 2NO +  4H2

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7
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1 mark

How many moles are present in 9 kg of glucose, C6H12O6?

Relative formula mass (Mr):       C6H12O6 = 180

  • 0.02 mol

  • 0.05 mol

  • 20 mol

  • 50 mol

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8
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1 mark

What is the mass of 0.25 moles of hydrated copper(II) sulfate, CuSO4.5H2O?

Relative formula mass (Mr):  H2O = 18  CuSO4 = 160

  • 40.0 g

  • 44.5 g

  • 62.5g

  • 1000 g

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9
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1 mark

2.7 g aluminium reacts with 38.1 g of iodine, I2, to make 40.8 g aluminium iodide, AlI3.

Relative atomic masses (Ar):     Al = 27        I = 127

Relative formula mass (Mr):      AlI3 = 408

What coefficients would balance the equation for the reaction?

  • 1 : 3 : 2

  • 2 : 1 : 2

  • 2 : 3 : 2

  • 3 : 2 : 3

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10
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1 mark

Nitrogen and hydrogen react together to make ammonia.

N2 + 3H2  2NH3

If 2.0 g of hydrogen is added to 12.0 g of nitrogen which substance is the limiting reactant and how much of the excess reactant remains?

Relative atomic masses (Ar): H = 1    N = 14

  Limiting Reactant Mass of excess reactant
A nitrogen 2.0 g
B nitrogen 10.0 g
C hydrogen 2.7 g
D hydrogen 9.3 g

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11
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1 mark

When 12 g of carbon (C) burns in oxygen (O2), 44 g of carbon dioxide (CO2) is formed.

What mass of C would burn to form 11 g of CO2?

  • 3 g

  • 4 g

  • 11 g

  • 12 g

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121 mark

Lead nitrate contains lead ions, Pb2+, and nitrate ions, NO3-.

What is the formula for lead nitrate?

  • PbNO3

  • Pb(NO3)2

  • Pb2NO3

  • Pb2(NO3)2

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13
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1 mark

Hydrogen gas can be made by reacting methane and steam (H2O).

CH4 + H2O rightwards arrow3H2 + CO

6 g of hydrogen gas can be made from 18 g of steam, H2O.

How much hydrogen gas can be made from 3.6 g of steam, H2O?

  • 0.4 g

  • 0.6 g

  • 1.2 g

  • 6.8 g

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141 mark

Ethanol, C2H5OH, burns in oxygen. Carbon dioxide and water are made.

Which equation for this reaction is correctly balanced?

  • C2H5OH + O2 → CO2 + H2O

  • C2H5OH + 3O2 → 2CO2 + 3H2O

  • C2H5OH + 2O2 → 3CO2 + 2H2O

  • 2C2H5OH + 7O2 → 4CO2 + 6H2O

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151 mark

Oxygen reacts with 1.20 g of carbon. 4.40 g of carbon dioxide forms.

C + O2 → CO2

What mass of oxygen is used in this reaction?

  • 0.80 g

  • 1.60 g

  • 3.20 g

  • 5.60 g

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161 mark

The formula of a magnesium ion is Mg2+.

The formula of a nitrate ion is NO3-.

What is the formula of magnesium nitrate?

  • MgNO3

  • Mg2NO3

  • Mg(NO3)2

  • Mg2(NO3)3

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17
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1 mark

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Urea, (NH2)2CO, is a fertiliser.

A student makes 1 mole of urea from 2 moles of ammonia.

What is the mass of urea that the student makes?

  • 43.0 g

  • 44.0 g

  • 58.0 g

  • 60.0 g

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181 mark

Magnesium reacts with chlorine. Magnesium chloride is made.

What is the balanced symbol equation for this reaction?

  • Mg + Cl → MgCl

  • Mg + Cl2 → MgCl2

  • 2Mg + Cl2 → 2MgCl

  • 2Mg + Cl2 → Mg2Cl2

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191 mark

Which of these shows the balanced symbol equation for the reaction between potassium and chlorine to make potassium chloride?

  • K + Cl2 ➞ KCl2

  • P + Cl2 ➞ PCl2

  • 2K + Cl2 ➞ 2KCl

  • 2P + Cl2 ➞ 2PCl

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201 mark

Magnesium is heated in a crucible.

q11-paper-3-june-2018-ocr-gcse-chem

The mass of the crucible and magnesium increases.

Which statement is the best explanation for this?

  • Oxygen is given off.

  • The magnesium melts.

  • The magnesium is oxidised to magnesium oxide.

  • The magnesium reacts to make magnesium carbonate.

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211 mark

Higher Only

A student neutralises nitric acid with potassium hydroxide solution.

Which equation shows the ionic equation for neutralisation?

  • HNO3 + KOH → KNO3 + H2O

  • H+ + OH → H2O

  • NO3 + K+ → KNO3

  • H+ + NO3 → HNO3

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22
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1 mark

Higher Only

What is the amount, in mol, of 15 g of carbonate ions, CO32-?

  • 0.18

  • 0.25

  • 4.0

  • 5.6

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231 mark

The accurate relative atomic mass of aluminium is 26.9815385.

What is this number to 5 significant figures?

  • 26.98153

  • 26.981

  • 26.98154

  • 26.982

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241 mark

Look at the diagram.

q15-paper-3-specimen-2016-ocr-gcse-chem

It shows how the reaction between hydrochloric acid and marble chips (calcium carbonate) can be monitored.

The reading on the balance decreases during the reaction.

Which statement is the best explanation?

  • Acid escapes from the flask.

  • Carbon dioxide gas is made which leaves the flask.

  • Hydrogen gas is made which leaves the flask.

  • The temperature in the laboratory changes.

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