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This question is about gases - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2022 - Paper 1
Question 2
This question is about gases. (a) When sodium is added to water, hydrogen gas is produced. Which observation shows that a gas has been produced? A a white precip... show full transcript
Worked Solution & Example Answer:This question is about gases - Edexcel - GCSE Chemistry Combined Science - Question 2 - 2022 - Paper 1
Step 1
When sodium is added to water, hydrogen gas is produced. Which observation shows that a gas has been produced?
Answer
The correct observation indicating that a gas has been produced is B effervescence is seen. This is a common indication of gas generation, specifically hydrogen in this reaction.
Step 2
Step 3
When 5.000 g of calcium carbonate is heated, the mass of solid remaining is _________.
Answer
To calculate the mass of solid remaining after the decomposition of calcium carbonate, we need to consider the reaction:
ightarrow ext{CaO} (s) + ext{CO}_2 (g)$$ When calcium carbonate decomposes, some mass is lost as carbon dioxide gas. Assuming the molar mass of CaCO₃ is approximately 100.09 g/mol and that of CaO is about 56.08 g/mol, we can proceed as follows: 1. Calculate the moles of CaCO₃: $$ ext{Moles of CaCO}_3 = rac{5.000 ext{ g}}{100.09 ext{ g/mol}} \\ ext{Moles of CaCO}_3 ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } ext{ } = 0.0499 ext{ mol}$$ 2. From the reaction stoichiometry, 1 mole of CaCO₃ yields 1 mole of CaO and 1 mole of CO₂. Therefore, 0.0499 moles of CaCO₃ produces 0.0499 moles of CaO. 3. Calculate the mass of CaO produced: $$ ext{Mass of CaO} = 0.0499 ext{ mol} imes 56.08 ext{ g/mol} = 2.80 ext{ g}$$ Thus, the mass of solid (CaO) remaining is approximately **2.80 g**.