(a) (i) Ethanoic acid, CH₃COOH, reacts with ethanol to form ethyl ethanoate and water - Edexcel - GCSE Chemistry - Question 5 - 2016 - Paper 1

When solid calcium carbonate is added to dilute ethanoic acid, you would observe effervescence or fizzing due to the evolution of carbon dioxide gas. Additionally, the solid may begin to dissolve as the reaction proceeds.

To find the concentration of ethanoic acid:

Given:

• Mass of ethanoic acid = 6.0 g
• Relative molecular mass = 60 g/mol

First, calculate the number of moles of ethanoic acid:

$n = \frac{\text{mass}}{\text{molar mass}} = \frac{6.0}{60} = 0.1 \text{ mol}$

Next, since the volume of the solution is 1.0 dm³:

$\text{Concentration} = \frac{n}{\text{Volume}} = \frac{0.1}{1.0} = 0.1 \text{ mol dm}^{-3}$

Thus, the answer is A 0.1.