This question is about silver iodide - AQA - GCSE Chemistry - Question 3 - 2020 - Paper 1
Question 3
This question is about silver iodide.
Silver iodide is produced in the reaction between silver nitrate solution and sodium iodide solution.
The equation for the re... show full transcript
Worked Solution & Example Answer:This question is about silver iodide - AQA - GCSE Chemistry - Question 3 - 2020 - Paper 1
Step 1
Explain how the results demonstrate the law of conservation of mass.
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Answer
The total mass before the reaction was measured as 156.76 g (78.26 g in beaker A and 78.50 g in beaker B). After the reaction was completed, the total mass remained the same at 156.76 g (108.22 g in beaker A and 48.54 g in beaker B). This shows that no mass was lost during the reaction, adhering to the law of conservation of mass.
Step 2
Suggest how the student could separate the insoluble silver iodide from the mixture at the end of the reaction.
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The student could use filtration to separate the insoluble silver iodide from the liquid mixture.
Step 3
Suggest one impurity that was removed by rinsing with water.
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One impurity that was removed by rinsing with water could be sodium nitrate.
Step 4
Suggest why the student warmed the silver iodide.
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The student warmed the silver iodide to help remove any remaining impurities and to facilitate the drying process.
Step 5
Calculate the percentage atom economy for the production of silver iodide in this reaction.
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The total molar mass of the reactants is: ( 170 + 150 = 320 ).
The molar mass of the useful product (silver iodide) is 235.
Thus, the percentage atom economy is calculated as:
(320235)×100=73.4375%
Rounded to three significant figures, the atom economy is 73.4%.
Step 6
Give one reason why reactions with a high atom economy are used in industry.
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Reactions with a high atom economy are preferred in industry because they are more sustainable, as they produce less waste and maximize the amount of useful product produced from the reactants.
