Practice Paper 1 (Edexcel IGCSE Chemistry)

A student carries out a titration to find the concentration of a solution of sulfuric acid, H₂SO₄.

She titrates 25.00 cm³ of sulfuric acid against 0.80 mol/dm³ sodium hydroxide, NaOH.

The results of the titrations are shown

Complete the table of results and tick (✓) the concordant results.

Use your concordant result to calculate the average volume of NaOH used.

i) Write the equation for the reaction.

ii) Calculate the number of moles of NaOH in the average volume used.

iii) Calculate the number of moles of H₂SO₄ in 25cm³ of the sulfuric acid.

iv ) Calculate the concentration of the sulfuric acid in mol/dm³.

Separate: Chemistry Only

Which two properties make aluminium suitable as the metal used as cans for drinks?

A reaction took place between iron sulfate and magnesium.

iron(II) sulfate + magnesium → magnesium sulfate + iron

Which species has been oxidised?

The chemical equation for the preparation of lead(II) sulfate is written below.

Pb(NO₃)₂ () + Na₂SO₄ () → PbSO₄ () + 2NaNO₃ ()

What are the state symbols for each substance in this reaction?

Three consecutive straight-chain members of the same homologous series are pentane, hexane and heptane.

Pentane is the compound containing the least number of carbon atoms.

Suggest the molecular formula of heptane.

Draw one line from each alkane to its boiling point.

Alkynes are hydrocarbons with the general formula C_nH_2n-2. The alkyne containing 2 carbon atoms is ethyne, C₂H₂.

State, with a reason, whether the boiling point of ethyne would be expected to be higher or lower than the boiling point of ethane, C₂H₆.

Complete the dot-and-cross diagram for a molecule of ethyne, C₂H₂.

The alkenes are unsaturated hydrocarbons. They form a homologous series, the members of which undergo the following chemical reaction.

• addition reactions
• polymerization
• combustion.

Alkenes that have one carbon-carbon double bond have the same empirical formula.

i) State their empirical formula.

ii) Why is the empirical formula the same for these alkenes?

Complete the following equation for the addition reaction of propene.

CH₃–CH=CH₂ + Br₂ → ....................................

Draw the repeat unit of poly(propene).

0.01 moles of an alkene needed 2.4 g of oxygen for complete combustion. 2.2 g of carbon dioxide were formed.

i) Determine the following mole ratio.

moles of alkene : moles of O₂ : moles of CO₂

From this ratio determine the formula of the alkene.

ii) Write an equation for the complete combustion of this alkene.

Crude oil is an important source of organic compounds.

The diagram shows crude oil being separated into different fractions.

i) Name the process used to separate crude oil into different fractions.

ii) State what happens to the crude oil at X.

iii) Describe the differences between fraction B and fraction E. In your answer, refer to

• size of the molecules
• boiling point
• colour
• viscosity

Crude oil often contains sulfur as an impurity.

Explain why this is a problem when using crude oil fractions as fuels.

Compound X is a hydrocarbon with an M_r of 70 that contains 85.7% by mass of carbon. When bromine water is added to compound X it remains orange.

Calculate the empirical formula of compound X

Using the information in part a), determine the structure of compound X.

Compound X reacts with chlorine in the presence of ultra-violet light. Write the equation for this reaction.

The reaction between hydrogen and chlorine is exothermic. This is the equation for the reaction.

H₂ (g) + Cl₂ (g) → 2HCl (g) ΔH = −184kJ

State the meaning of the term exothermic.

Separate: Chemistry Only

The table gives the bond energies for the H–H and H–Cl bonds.

Use the equation and information from the table to calculate the bond energy of the Cl–Cl bond.

bond energy = .............................................................. kJ/mol

Separate: Chemistry Only

Explain why this reaction is exothermic. Refer to bond-breaking and bond-making in your answer.

Separate: Chemistry Only

Complete the reaction profile diagram to show the position of the products, the enthalpy change (ΔH) and the activation energy (E_a) for the reaction.

The diagram below shows two different atoms of hydrogen.

Which particle is furthest from the centre of each atom?

The diagram shows the displayed formula of the organic compound methanol, CH₃OH

i) Determine the number of atoms in one molecule of methanol.

ii) State why methanol is not a hydrocarbon.

The atoms in methanol are held together by covalent bonds.

i) State what is meant by the term covalent bond.

ii) Draw a dot-and-cross diagram to show the bonding in a molecule of methanol. Show only the outer electrons of each atom.

Another organic compound has the percentage composition by mass

C = 38.7% H = 9.7% O = 51.6%

i) Calculate the empirical formula of this compound.

empirical formula = ..............................................................

ii) The relative molecular mass (M_r) of the compound is 62 Determine the molecular formula of the compound.

molecular formula = ........................................................