Chem Rate of Rxn Ws3

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 1 of 8 Name: _____________________( ) Class: _______ Date ________ 1. The graph shows the total volume of carbon dioxide evolved, plotted against time, when excess calcium carbonate reacts with 20 cm3 of hydrochloric acid containing 2moldm-3. (a) Give a balanced chemical equation for the reaction above. __________________________________________________________________ (b) Indicate clearly on the graph above the time taken for the reaction to end (TE) (c) Indicate clearly on the graph how the rate of the reaction can be obtained at pt X (d) Read the facts provided and answer the following questions. (i) What is the name of the product measured? ______________________________ (ii) How is the product in (di) collected and measured for the rate of reaction? _________________________________________________________________ (iii) What are the reactants present? _______________ and ____________________ (iv) Which reactant will be used up first? Explain. _________________________________________________________________ (e) If the experiment was repeated but this time the concentration of the acid was changed to 0.5mol/dm3, sketch on the graph above what you would expect and label the graph as Rxn II (f) Explain in terms of the collision theory how concentration has affected the rate of reaction.

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 2 of 8 _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ 2. Two experiments are carried out using the apparatus below. In experiment 1, dilute acid is used In experiment 2, more concentrated hydrochloric acid is used. All other conditions are the same and in both experiments all the marble chips completely react. (a) What is the chemical formula of marble chip? _________________________ (b) What is the observation when marble chip allowed to react with hydrochloric acid? ______________________________________________________________ ______________________________________________________________ (c) Give a balanced chemical equation of the above reaction. ______________________________________________________________ (d) State the difference in terms of ions between the two acids in experiment 1 and 2. ______________________________________________________________ (e) Which diagram shows the correct results obtained for the above experiments?

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 3 of 8 Explain your answer in (e) _________________________________________________________________ _________________________________________________________________ 3. Curve 2 shows the volume of carbon dioxide given off when 5 g of calcium carbonate lumps react completely with an excess of 1.0 mol/dm3 hydrochloric acid at 40°C State three different changes that can produce curve 1. (a)_________________________________________________________________ (b) _________________________________________________________________ (c) _________________________________________________________________ 4. Indicate at the side of each statement whether they are True or False

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 4 of 8 (a) Curve 1 was obtained when 1 g of granulated zinc reacted with an excess of hydrochloric acid at 30°C. (b) The graph shows how the total volume of hydrogen produced by reaction between hydrochloric acid and an excess of magnesium varied with time. (c) One way to study the rate of a reaction is to measure the volume of gas given off during the reaction with a gas syringe. This technique could be conveniently applied the following:

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 5 of 8 (d) Magnesium metal was placed in a flask on a balance and excess dilute hydrochloric acid:was added. The graph below slows how the total mass of flask and contents varies with time. 5. 0.10 g of magnesium ribbon was allowed to react at 18°C with 20 cm3 of 1 mol/dm3 hydrochloric acid at atmospheric pressure. The total volume of hydrogen collected was noted at half minute intervals and the graph below was plotted. magnesium

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 6 of 8 (a) What time was required for half the magnesium to react? __________________________________________________________________ 5. Sketching of Graph 2 Important Principles: • The Maximum Volume of Gas is dependent on the Number of moles of reactant • The Gradient of the Curve is dependent on the Concentration of the acid. a. An excess of marble chip reacted with 30cm3 of 2.5 mol/dm3 nitric acid. Sketch both graph as stated. b. An excess of marble chip reacted with 100cm3 of 1.5 mol/dm3 hydrochloric acid. Sketch both graph as stated.

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 7 of 8 c. Two experiments (I and II) were carried out to measure the rate of production of hydrogen from the reaction below. Given that : 2K (s) + 2HCl (aq)  2KCl (aq) + H2 (g) Reaction I: 100 cm3 of 3 mol/dm3 of HCl Reaction II: 400 cm3 of 1.5 mol/dm3 of HCl

Secondary 4 Express Pure Chemistry – Rate of Reaction Worksheet 3 SDL Page 8 of 8 Elements of Thinking Questions Student’s response Rate of Reaction Worksheet 3 SDL Qn 5c Question at Issue What is the problem or Issue?  Read the questions carefully, underline the command : eg Explain/Describe/Calculate  Ask yourself what chapter is this question on. Command:…………………………………. Chapter:………………………………………………… Information What data, facts, evidence, observations, experiences or reasons are being used?  Underline the keywords/info in the question Key info: Interpretation and Inferences What conclusions may be reached?  What can I infer from these info? Inference: Concepts What are theories, definitions, laws, principles and models that can be used to understand the issue or problem?  Think of all the definitions/concepts/formulae and CFS you know about the chapter(s) Relevant formulae/Concepts/Definitions: Assumptions What is being taken for granted?  Any assumption/formula for this theory to be true? Assumption: After applying the thinking routine, organise your facts to answer the question within context and pay close attention to using keywords. Apply CARP/criteria for success (Clarity, Accuracy, Relevance and Precision)