A-Level AQA Chemistry The Mole, Avogadro & The Ideal Gas Equation: Some 1.0 mol dm-3 sol

Some 1.0 mol dm-3 solutions were mixed using equal volumes of each solution - AQA - A-Level Chemistry - Question 31 - 2018 - Paper 3

Question 31

Some 1.0 mol dm-3 solutions were mixed using equal volumes of each solution. Which pair of solutions would give the greatest mass of solid? A. Ba(OH)<su... show full transcript

Worked Solution & Example Answer:Some 1.0 mol dm-3 solutions were mixed using equal volumes of each solution - AQA - A-Level Chemistry - Question 31 - 2018 - Paper 3

Step 1

Which pair of solutions would give the greatest mass of solid?

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Answer

To determine which pair of solutions gives the greatest mass of solid when mixed, we consider the potential precipitate formed by the reaction of Ba(OH)2 with sulfate ions from Na2SO4.

Identify Potential Precipitate: Ba(OH)2 dissociates into Ba2+ and OH- ions. The sulfate ions (SO42-) from Na2SO4 can react with Ba2+ to precipitate barium sulfate (BaSO4), which is insoluble in water.
Calculate the Products: The balanced equation for this reaction is: $ext{Ba(OH)}_2 + ext{Na}_2 ext{SO}_4 \rightarrow ext{BaSO}_4 (s) + 2 ext{NaOH}$ For every mole of Ba(OH)2, one mole of BaSO4 is produced.
Assessing Other Options:
- A: Ba(OH)2 + MgCl2 does not produce BaSO4.
- B: Ba(OH)2 + MgSO4 also produces Mg(OH)2, but not as much solid mass as BaSO4.
- C: Ba(OH)2 + NaCl produces no precipitate.
Conclusion: D. Ba(OH)2 and Na2SO4 would yield the greatest mass of solid, due to the formation of BaSO4.

Some 1.0 mol dm<sup>-3</sup> solutions were mixed using equal volumes of each solution - AQA - A-Level Chemistry - Question 31 - 2018 - Paper 3

Worked Solution & Example Answer:Some 1.0 mol dm<sup>-3</sup> solutions were mixed using equal volumes of each solution - AQA - A-Level Chemistry - Question 31 - 2018 - Paper 3

Which pair of solutions would give the greatest mass of solid?

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