Changing the concentration of the reactants

2 marks · Hard

An experiment produced 0.46 g of carbon dioxide in the first 20 seconds during the reaction of marble chips with dilute hydrochloric acid. Calculate the average rate of carbon dioxide production, giving your answer in g/s. Show your working.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

Show answer

0.023 g/s (±0.001)

Must show: Shows calculation: 0.46 / 20

Common mistakes: Forgets to divide by time; Incorrect units (e.g. gives answer in g/min rather than g/s)

Show mark scheme and worked solution

Marking points

M1 · 1 mark · Writes and/or applies the correct equation for average rate: average rate = mass / time (or shows 0.46 / 20 in working).

A1 · 1 mark · Obtains correct answer: 0.023 g/s (allow rounding to 2 or 3 significant figures and minor error carried forward). (follow-through)

Worked solution

Average rate = mass / time = 0.46 g / 20 s = 0.023 g/s