Redox, Group 2 and Group 7 hw - AS LEVEL CHEMISTRY 1.1.4...

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Paddington Academy 1 AS LEVEL CHEMISTRY 1.1.4 REDOX 1.3.2 GROUP 2 1.3.3 GROUP 7 ASSESSED HOMEWORK Answer all questions Max 90 marks Name …………………………………………………………….. Mark ……../90 …… .... % Grade ………
Paddington Academy 2 1. The Group 2 element radium, Ra, is used in medicine for the treatment of cancer. Radium was discovered in 1898 by Pierre and Marie Curie by extracting radium chloride from its main ore pitchblende. (a) Predict the formula of radium chloride. ......................................................................................................................... [1] (b) Pierre and Marie Curie extracted radium from radium chloride by reduction. Explain what is meant by reduction , using this reaction as an example. ......................................................................................................................... ......................................................................................................................... [2] [Total 3 marks] 2. The reaction between magnesium and sulfuric acid is a redox reaction. Mg(s) + H 2 SO 4 (aq) MgSO 4 (aq) + H 2 (g) (i) Use oxidation numbers to identify which element has been oxidised. Explain your answer. element oxidised ............................................................................................. explanation ...................................................................................................... ......................................................................................................................... [2] (ii) Describe what you would see when magnesium reacts with an excess of sulfuric acid. ......................................................................................................................... ......................................................................................................................... [2] [Total 4 marks]
Paddington Academy 3 3. A student prepared an aqueous solution of calcium chloride by reacting calcium with hydrochloric acid. Ca(s) + 2HC l (aq) CaC l 2 (aq) + H 2 (g) (i) Using oxidation numbers, show that this is a redox reaction. ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... [2] (ii) The student had added the exact amount of calcium required to react with the hydrochloric acid used. After carrying out the experiment, the student accidentally added some more calcium. The student was surprised that the extra calcium still reacted. Explain this observation. Include an equation in your answer. ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... [2] [Total 4 marks]
Paddington Academy 4 4. Magnesium reacts with oxygen to form magnesium oxide. 2Mg(s) O 2 (g) 2MgO(s) Use oxidation numbers to show that oxygen has been reduced in its reaction with magnesium. ......................................................................................................................... ......................................................................................................................... ......................................................................................................................... [Total 2 marks] 5. Barium reacts with water in a redox reaction. Ba(s) 2H 2 O(l) Ba(OH) 2 (aq) H 2 (i) Explain, in terms of electrons, what is meant by oxidation. (g) ......................................................................................................................... [1] (ii) Which element has been oxidised in this reaction? Deduce the change in its oxidation number. element ........................................................................................................... oxidation number changes from ………… to………… [2] [Total 3 marks]
Paddington Academy 5

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