CIE Jun 2014 v3 Paper 5 Q1

Answers available below

PMT When magnesium nitrate(V) is heated, it decomposes to form magnesium oxide, nitrogen(IV) oxide and oxygen. Nitrogen(IV) oxide is an acidic gas that reacts readily and completely with alkalis. You are to plan a single experiment to con rm that the molar quantities of magnesium oxide, nitrogen(IV) oxide and oxygen produced agree with the equation for the thermal decomposition of magnesium nitrate(V). The following information gives some of the hazards associated with nitrogen(IV) oxide. Nitrogen(IV) oxide must not be inhaled. A large dose can be fatal and smaller quantities can have severe effects on breathing, particularly for people who suffer from asthma. You are provided with anhydrous magnesium nitrate(V) and have access to the usual laboratory equipment and reagents. (a) (i) Write an equation for the thermal decomposition of magnesium nitrate(V).[1] (ii) Calculate the mass of magnesium oxide and volumes of nitrogen(IV) oxide and oxygen produced under room conditions when 1 mole of magnesium nitrate(V) is heated. [Ar: O, 16.0; Mg, 24.3] You should assume that one mole of any gas occupies 24.0 dm3 under room conditions. [1]UCLES 2014 9701/53/M/J/14<br /> (b) (i) Draw and label a diagram of the apparatus and experimental set-up you would use. The set-up needs to be capable of absorbing the nitrogen(IV) oxide and collecting the oxygen separately and in sequence. PMT (ii) State the volume of the gas collector to be used to collect oxygen in (i). Calculate a mass of magnesium nitrate(V) to be heated that would produce a stated volume of oxygen appropriate for the collector. [Ar: N, 14.0; O, 16.0; Mg, 24.3] You should assume that one mole of any gas occupies 24.0 dm3 under room conditions. [4]UCLES 2014 9701/53/M/J/14 [1] [Turn over<br /> PMT (c) List the measurements you would make when carrying out the experiment.[3] (d) (i) How could you make sure that the magnesium nitrate(V) had completely decomposed in the experiment?[1] (ii) To make sure that the volume of gas measured is accurate, what should you do before taking the measurement?[1] (e) Explain how you would use the results of the experiment to con rm that the decomposition had occurred according to the molar ratios in the equation.[2]UCLES 2014 9701/53/M/J/14<br /> PMT (f) What precautions would you take to make sure that the experiment could be performed safely?[1] [Total: 15]UCLES 2014 9701/53/M/J/14 [Turn over<br />

Show answer