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A student investigated how temperature affects the rate of reaction between magnesium carbonate and dilute hydrochloric acid - AQA - GCSE Chemistry - Question 8 - 2018 - Paper 2
Question 8
A student investigated how temperature affects the rate of reaction between magnesium carbonate and dilute hydrochloric acid. This is the method used. 1. Heat hydr... show full transcript
Worked Solution & Example Answer:A student investigated how temperature affects the rate of reaction between magnesium carbonate and dilute hydrochloric acid - AQA - GCSE Chemistry - Question 8 - 2018 - Paper 2
Step 1
Step 2
08.2 Plot the data from Table 5 on Figure 6. Draw a line of best fit.
Answer
To plot the data accurately, each time point from Table 5 corresponds to a loss of mass value. One would mark the points (0, 0), (20, 0.26), (40, 0.48), (60, 0.67), (80, 0.82), (100, 0.91), (120, 0.96), and (140, 0.99) on Figure 6. A line of best fit should be drawn through these points, showing an upward trend as time increases.
Step 3
08.3 Determine the rate of reaction at 50 °C when the loss of mass is 0.95 g.
Answer
To find the rate of reaction, we need to draw a tangent line to the graph at the point where the loss of mass is 0.95 g. This tangent will intersect the vertical axis (loss of mass) at 0.95 g and the horizontal axis (time) at its corresponding time value. The slope of this tangent represents the rate of reaction:
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Identify the point on the graph where the loss of mass is 0.95 g.
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Draw a tangent line at that point.
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Choose two points on this tangent to calculate the slope:
- For example, if one point is (100s, 0.91g) and another point is (120s, 0.96g), the change in mass (
Δy = 0.96 g - 0.91 g = 0.05 g
) and the change in time (
Δx = 120s - 100s = 20s
). The rate of reaction is given by:
Rate = rac{Δy}{Δx} = rac{0.05}{20} = 0.0025 g/s.
Finally, round this value to 2 significant figures to get 0.0025 g/s.