AS Chemistry Bridging Work All of the work contained is GCSE standard and is designed to make sure you are up to speed before starting the AS course. Total Mark: Question Marks: Q1: / Q2: / Q3: / Q4: / Grade: What went well: Even better if:
Section 1: Atomic Structure Q1a. In as much detail as you can, describe the structure of an atom of an element of your choice. Include all relevant information about sub-atomic particles and what information is provided by the periodic table. Include a diagram Q1. Explain why Chlorine has a mass number of 35.5 (12)
Section 2: Bonding and structure types Q2. For each of the diagrams below, explain what type of structure it is, explain the type of bond that is holding it together, and describe and explain whether it has a high or low melting/boiling point and whether it conducts electricity. (20)
Section 3: Maths and balancing Part 1: (24) Part 2: Work out the formula of the following ionic substances:
Part 3: Part 4: Using moles
Section 4: GCSE exam questions. Anything included overlaps with something in A-level. If you are unsure of how to answer, research the topic being covered Q1.This question is about sodium chloride and iodine. (a) Describe the structure and bonding in sodium chloride............. (4) (d) The bonding in iodine is similar to the bonding in chlorine. (i) Complete the diagram below to show the bonding in iodine. Show the outer electrons only. (ii) Explain why iodine has a low melting point. (3) (iii) Explain, in terms of particles, why liquid iodine does not conduct electricity. (Total 11 marks)
Q2. The apparatus shown in the diagram was used to investigate the rate of reaction of excess marble chips with dilute hydrochloric acid; HCl. Marble is calcium carbonate, formula CaCO 3. The salt formed is calcium chloride, CaCl 2. (a) Write a balanced equation for the reaction....... The following results were obtained from the experiment. Time in minutes Reading on balance in g 0.5 269.6 1.0 269.3 2.0 269.0 3.0 268.8 5.0 268.7 9.0 268.6 (b) (i) Plot the results and draw a graph on the axes below.
(3) (ii) Continue the graph you have drawn to show the expected reading after11 minutes. (iii) On the axes above, sketch a graph of the result which would be obtained if in a similar experiment the same mass of powdered marble was used instead of marble chips. (Total 8 marks) Q3.Ammonia is produced from nitrogen and hydrogen. The equation for this reaction is: (a) (i) A company wants to make 6.8 tonnes of ammonia. Calculate the mass of nitrogen needed. Relative atomic masses (A r): H = 1; N = 14 Mass of nitrogen =... tonnes (3)
(ii) The company expected to make 6.8 tonnes of ammonia. The yield of ammonia was only 4.2 tonnes. Calculate the percentage yield of ammonia. Percentage yield of ammonia =... % (iii) Use the equation above to explain why the percentage yield of ammonia was less than expected. (Total 6 marks) Q4.In 1884 Arrhenius put forward ideas to explain acid-base behaviour. It was many years before his ideas were accepted. Use the ideas of Arrhenius to answer parts (a) and (b). (a) Hydrochloric acid is made by dissolving hydrogen chloride gas in water. An equation which represents this reaction is: Explain why a solution of hydrogen chloride in water is acidic dry hydrogen chloride gas is not acidic.......... (Total 2 marks) Q5 (a) Magnesium can be produced from magnesium oxide. The equation for the reaction is: Si(s) + 2 MgO(s) SiO 2(s) + 2 Mg(g) (i) How can you tell from the equation that the reaction is done at a high temperature?
(ii) This reaction to produce magnesium from magnesium oxide is endothermic. What is meant by an endothermic reaction? (iii) A company made magnesium using this reaction. Calculate the mass of magnesium oxide needed to produce 1.2 tonnes of magnesium. Relative atomic masses (A r): O = 16; Mg = 24 Mass of magnesium oxide needed =... tonnes (3) (iv) The company calculated that they would produce 1.2 tonnes of magnesium, but only 0.9 tonnes was produced. Calculate the percentage yield. Percentage yield =... % (v) Give one reason why the calculated yield of magnesium might not be obtained. (Total 7 marks) Q6. One of the pigments used in cave paintings contains: 70 % of iron (Fe) and 30 % of oxygen (O) Calculate the simplest (empirical) formula of this substance............. (4) (Total 4 marks)