Practice Paper 2 (DP IB Chemistry: SL)

Explain what is meant by the standard enthalpy change of reaction.

An enthalpy level diagram for the reaction between solid ammonium nitrate and water is shown below.

Figure 1 

The enthalpy of combustion for propanol is, ΔH_c^ϴ, is -2021 kJ mol^-1. Draw a labelled energy level diagram for this reaction.

Malonic acid is a naturally occurring acid found in fruits and vegetables and is shown in Figure 1.

Figure 1 

The first dissociation of malonic acid is:

C₃H₄O₄ (aq) + H₂O (l) ⇌ C₃H₃O₄^- (aq) + H₃O⁺ (aq)

Identify one conjugate acid-base pair from the equation.

The anion C₃H₃O₄^- may be classified as amphiprotic. Explain the meaning of amphiprotic and write equations, using C₃H₃O₄^-_, to illustrate your answer.

Write an equation to show how malonic acid reacts with magnesium.

Under the right conditions, malonic acid can react with ethanol to form diethyl malonate, a diester.

Draw a displayed formula for diethyl malonate showing all the bonds.

Ethene, C₂H₄, can be made into a number of useful compounds. A reaction sequence for this is shown below:

The product of step 2 can undergo combustion.

Give the reagents and conditions needed to carry out step 3.

The product of step 2 has a higher boiling point than the product of step 3.

State the names of the products of step 2 and 3, and explain the difference in their boiling points.

State three ways of monitoring concentration changes in a reaction.

A reaction is monitored by measuring the volume of a gas produced every 10 seconds. State an appropriate unit to use.

Sketch a graph to show the volume of gas produced during the course of an experiment against the time taken.

State the effect that increasing concentration has on the rate of a reaction.

Tetrafluoroethene, C₂F₄, and tetrafluorohydrazine, N₂F₄, are fluorides of adjacent elements in the Periodic Table.

4Draw the Lewis (electron dot) structures for C₂F₄ and N₂F₄ showing all valance electrons.

Predict and explain the F-C-F bond angle in tetrafluoroethene and the F-N-F bond angle in tetrafluorohydrazine.

Tetrafluorohydrazine is a polar molecule but tetrafluoroethene is not.

Explain the difference in molecular polarity.