Chemistry 5070 · O Level · Exothermic and endothermic reactions

Exothermic and endothermic reactions — practice question

When magnesium powder is introduced into excess hydrochloric acid, the temperature increases.
(a(i))[1]

What kind of reaction is shown by the temperature rise?

(a(ii))[2]

Besides the temperature increase, state two observations that can be seen while the reaction is happening.

(a(iii))[1]

Construct an equation for the reaction between magnesium powder and hydrochloric acid.

(b)[3]

Plot the data on the grid, draw a straight line through the points, and continue the line until it crosses the y-axis.

(c(i))[1]

Use your graph to find the temperature at $0$ minutes.

(c(ii))[1]

The hydrochloric acid started at $20.0^\circ\text{C}$. Use your answer to (c)(i) to calculate the maximum temperature rise.

(d(i))[1]

Calculate the amount of heat energy in joules (J) needed to raise the temperature of $50.0\text{ cm}^3$ of hydrochloric acid by $1^\circ\text{C}$, given that $4.2\text{ J}$ are needed to raise $1.0\text{ cm}^3$ by $1^\circ\text{C}$.

(d(ii))[1]

Calculate the amount of heat energy in joules (J) needed to raise the temperature of $50.0\text{ cm}^3$ of hydrochloric acid by the maximum temperature rise calculated in (c)(ii).

Worked solution & mark scheme

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