HSC Chemistry Practice Exam

Which of the following chemical systems represents an exothermic chemical change?

• H₂O_(l) -> H₂O_(g)

• H₂O_(g) -> H₂O_(l)

• H_2(g) + ½ O_2(g) -> H₂O_(l)

• H₂O_(l) -> H_2(g) + ½ O_2(g)

1. Which of the following curves would represent the change in pH in a conical flask when a solution of hydrochloric acid (from a burette) is added to a solution of sodium hydroxide (in the conical flask)?

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Which of the following combinations could be used to produce a buffer solution?

• CH3COOH and CH3COONa

• NH4OH and CH3COOH

• NaOH and NaCl

• HCl and NaCl

Bromothymol blue is an acid/base indicator which can be used to test the pH of swimming pools and fish tanks. It changes from yellow to blue across a pH range of 6.0 – 7.5. Which alternative matches the solutions shown with the correct indicator colour?

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If equal volumes of 0.10 mol L–1 HCl solution and 0.10 mol L–1 HNO₂ solution are compared, which would be true of the HNO_2­ solution?

• It would have a higher pH.

• It would have a higher hydronium ion concentration.

• It would produce a smaller volume of hydrogen gas when reacted with magnesium.

• It would require a smaller volume of 0.10 mol L–1 NaOH solution for neutralisation

The figure below shows the change in the concentration of reactant and products as a function of time for the reaction:

• The temperature was suddenly increased.

• The pressure of the system was decreased.

• The volume of the vessel was suddenly decreased.

• Additional nitrogen gas was injected into the vessel

Which of the following is a correct statement about compounds of a homologous series?

• Each homologue has at least 2 isomers.

• Each subsequent molecular mass increases by 14 g/mol

• All compounds in the series have the same empirical formula

• Each molecular formula varies from the next by the addition of CH3.

1. Which two species act as Brønsted-Lowry acids in the following reaction?

H2SO3 (aq) + H2O (aq) ⇌ H3O+ (aq) + HSO3– (aq)

• H2SO3 and H3O+

• H2O and H2SO3

• H2O and H3O+

• H2O and HSO3–

1. Carbon dioxide can be produced from carbon monoxide and oxygen gas. At 1000°C the reaction reaches equilibrium as shown below:

2CO (g) + O2 (g) ⇌ 2CO2 (g) ΔH = – 566 kJ/mol

Which of the following changes would not result in a larger yield of CO2 (g)?

• Adding a catalyst

• Decreasing the volume

• Decreasing the temperature

• Increasing the partial pressure of CO(g)

Identify the systematic IUPAC name for the compound shown above.

• 4-methyl-5-ethylhexane

• 2-ethyl-3-methylhexane

• 3,4-dimethylheptane

• 4,5-dimethylheptane