Edexcel Jan 2010 Paper 1 Q17

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PMT 17 Sulfamic acid is a white solid used by plumbers as a limescale remover. (a) Sulfamic acid contains 14.42% by mass of nitrogen, 3.09% hydrogen and 33.06% sulfur. The remainder is oxygen. (i) Calculate the empirical formula of sulfamic acid. (3) (ii) The molar mass of sulfamic acid is 97.1 g mol1. Use this information to deduce (1) (2) the molecular formula of sulfamic acid. (b) A solution of sulfamic acid contains hydrogen ions. The hydrogen ions react with magnesium to produce hydrogen gas. In an experiment, a solution containing 5.5103 moles of sulfamic acid was reacted with excess magnesium. The volume of hydrogen produced was 66 cm3, measured at room temperature and pressure. (i) Draw a labelled diagram of the apparatus you would use to carry out this experiment, showing how you would collect the hydrogen produced and measure its volume. 14 *N35131A01424*<br /> PMT (ii) Calculate the number of moles of hydrogen, H2, produced in this reaction. [The molar volume of a gas is 24 dm3mol1 at room temperature and pressure] (iii) Show that the data confirms that each mole of sulfamic acid produces one mole of hydrogen ions in solution. (c) Plumbers use sulfamic acid powder for descaling large items such as boilers. Sulfamic acid acts as a descaler because the hydrogen ions react with carbonate ions in limescale. (i) Write an ionic equation for the reaction of hydrogen ions with carbonate ions. State symbols are not required. (ii) Suggest ONE reason why sulfamic acid is considered less hazardous than hydrochloric acid as a descaler. (1) (2) (1) (1)(Total for Question 17 = 11 marks) *N35131A01524* 15 Turn over<br />

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