SASS Chem Speed of Reaction Topical

_______________________________________________________________________________________________________________________________________________________________________________________ Page 1 ST ANDREW’S SECONDARY SCHOOL NAME CLASS DATE CHEMISTRY Self-Assessment Topical Test 30 minutes Speed of Reaction INSTRUCTIONS Write your name, class and date on the spaces provided above. Complete all questions on this question paper. You are reminded to revise this topic first before attempting the questions. Multiple-Choice Questions [10 marks] 1 Which of these factors does not affect the speed of a chemical reaction? A Concentration of reactant B Colour of reactant C Surface area of reactant D Temperature of reactant ( ) 2 Which of the following solutions would react the fastest if added to the same amount of magnesium? A 4 g of acid in 50 cm3 of water B 10 g of acid in 100 cm3 of water C 40 g of acid in 250 cm3 of water D 100 g of acid in 1000 cm3 of water ( ) 3 In which reaction is pressure least likely to affect the reaction? A 2H2(g) + O2(g) → 2H2O(g) B NaOH(aq) + HCl(aq) → NaCl(aq) + H2O(l) C N2(g) + 3H2(g) → 2NH3(g) D 2SO2(g) + O2(g) → 2SO3(g) ( ) 4 Two reactants were mixed in a beaker and the mass of the beaker and its contents was recorded at regular time intervals. A graph of mass plotted against time is shown below. Which of the following are possible reactants? A Sodium hydroxide and hydrochloric acid B Copper(II) sulfate and zinc C Copper(II) carbonate and hydrochloric acid D Sodium hydroxide and copper(II) sulfate ( ) Time Mass

_______________________________________________________________________________________________________________________________________________________________________________________ Page 2 5 A teacher wanted to demonstrate a reaction between an acid and a solid reactant, but it was too violent to be safe. Which of these changes would make the reaction safer to demonstrate? Use the following information to answer Questions 6 - 9. In an experiment, a strip of magnesium ribbon is reacted with excess dilute hydrochloric acid. Curve X is obtained when the volume of hydrogen gas given off during the reaction is plotted against time. Which of the following changes to the experiment would produce graphs, A, B, C or D? 6 Only half the amount of magnesium is reacted with excess acid. ( ) 7 The acid is diluted to half of its original concentration but is still in excess. ( ) 8 The strip of magnesium ribbon is grounded into powder form and then reacted with the acid. ( ) 9 The strip of magnesium ribbon is grounded into powder form and then reacted with the acid, which has been warmed. ( ) 10 Which of the following properties of a catalyst does not change during a chemical reaction? A Appearance B Mass C Physical state D Surface area ( ) Acid Size of solid reactant Temperature Concentration A Lower Lower Larger B Lower Lower Smaller C Higher Higher Larger D Higher Higher Smaller ( ) Volume of hydrogen Time D C B A curve X

_______________________________________________________________________________________________________________________________________________________________________________________ Page 3 Structured Questions [15 marks] 11 Name four factors that can affect the rate at which a chemical reaction occurs. [4] 1. _____________________________________________ 2. _____________________________________________ 3. _____________________________________________ 4. _____________________________________________ 12 Some students investigated the effect of particle size of a reactant on the speed of reaction. Samples of quicklime (calcium oxide) of three particle sizes were dissolved in water and the temperature of each reaction mixture was measured at every half-minute for two minutes. The results of the experiments are shown in the table below. Time/min Temperature/ºC Powdered quicklime Large lumps of quicklime Small lumps of quicklime 0 25.0 25.0 25.0 0.5 30.0 26.0 28.0 1.0 43.0 28.0 37.0 1.5 56.0 31.0 46.0 2.0 54.0 30.0 44.0 (a) Explain the results in the table. [2] __________________________________________________________________________ __________________________________________________________________________ (b) What type of energy change has occurred? [1] __________________________________________________________________________ (c) Write a balanced chemical equation for the reaction between calcium oxide and water. [1] __________________________________________________________________________

_______________________________________________________________________________________________________________________________________________________________________________________ Page 4 13 Consider the reaction between magnesium and dilute hydrochloric acid. (a) (i) Describe how the speed of this reaction can be determined. [1] ______________________________________________________________________ ______________________________________________________________________ (ii) Draw a labelled diagram of a suitable experimental set-up. [2] (b) (i) Explain, in terms of effective collisions, how an increase in concentration of hydrochloric acid increases the speed of reaction. [2] ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ (ii) State two other methods that would increase the speed of this reaction. [2] 1. _____________________________________________ 2. _____________________________________________