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Aqua regia is made by mixing 30.0 mL of concentrated hydrochloric acid (12.0 mol/L) with 10.0 mL of…
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Aqua regia is made by mixing of concentrated hydrochloric acid () with of concentrated nitric acid (). Gold dissolves by the reaction . Take the molar mass of gold as . Find the moles of each acid, the largest mass of gold the mixture can dissolve, the volume of NO at and , and the moles of nitric acid left over.
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The worked solution
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Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Plan. Compare how much gold each acid could dissolve, and take the smaller.
Step 1. Moles. HCl: . HNO3: .
Step 2. The limit. HCl could dissolve of gold. HNO3 could dissolve . So hydrochloric acid limits.
Step 3. Gold. .
Step 4. Nitric oxide. of NO has a volume of .
Step 5. Nitric acid left. .
Answer: , of gold, of NO and of nitric acid left.
Check. The ratio of the acids in the mixture is 3 : 1 by volume, but the amounts are . The nitric acid is in excess.
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