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A 2.0 g piece of magnesium ribbon was added to a known volume of 2.0 M hydrochloric acid - VCE - SSCE Chemistry - Question 1 - 2008 - Paper 1
Question 1
A 2.0 g piece of magnesium ribbon was added to a known volume of 2.0 M hydrochloric acid. The volume of hydrogen gas produced during the reaction was measured and re... show full transcript
Worked Solution & Example Answer:A 2.0 g piece of magnesium ribbon was added to a known volume of 2.0 M hydrochloric acid - VCE - SSCE Chemistry - Question 1 - 2008 - Paper 1
Step 1
a. Write an equation for the reaction between magnesium and hydrochloric acid.
Answer
The balanced chemical equation for the reaction between magnesium (Mg) and hydrochloric acid (HCl) is:
This equation shows that one mole of magnesium reacts with two moles of hydrochloric acid to produce one mole of magnesium chloride and one mole of hydrogen gas.
Step 2
b. On the axes above, sketch the expected graph of volume of hydrogen against time for this second experiment. Give an explanation for the shape of your graph.
Answer
The expected graph for the second experiment, where magnesium powder is used instead of ribbon, will show a steeper initial increase in the volume of hydrogen gas produced compared to the first experiment.
Graph Sketch: (Where the y-axis represents the volume of hydrogen gas produced in liters and the x-axis represents time in seconds.)
Explanation: The magnesium powder has a greater surface area than the magnesium ribbon, allowing for a faster reaction rate with hydrochloric acid. As a result, hydrogen gas will be produced more rapidly at the start of the reaction, leading to a steeper slope in the graph. Eventually, the graph will plateau as the acid is consumed, indicating that the reaction has completed.