Short free-response question
Magnesium in hydrochloric acid
- Units 3 and 4
- 4 points
- About 9 minutes
You can use a calculator on this question, just like on exam day.
A shorter multipart question that sticks to one or two topics. Each part usually asks for one calculation, claim or explanation. On the exam: 4 questions (Questions 4–7), part of the 1-hour-45-minute free-response section; calculator allowed.
The question
A student places 0.120 g of magnesium ribbon in 25.0 mL of 1.00 M HCl(aq). Hydrogen gas is produced and collected in a gas syringe at 22.0 °C and 0.985 atm. The magnesium dissolves completely.
Suggested time: 9 minutes
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Part (a)
1 pointWrite the balanced net ionic equation for the reaction between Mg(s) and HCl(aq).
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Part (b)
1 pointIdentify the limiting reactant. Justify your answer with a calculation.
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Part (c)
1 pointCalculate the volume, in mL, of H₂(g) collected in the gas syringe.
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Part (d)
1 pointIdentify the element that is oxidized and the element that is reduced in the reaction. Justify your answer using oxidation numbers.
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