Chemistry 0620 · IGCSE · The characteristic properties of acids and bases

The characteristic properties of acids and bases — practice question

In water, calcium hydroxide, Ca(OH)$_2$, has only limited solubility.
(a(i))[2]

Write the chemical equation for the process.

(a(ii))[1]

Name a different substance that reacts with water to produce calcium hydroxide.

(b(i))[1]

Suggest the pH for a calcium hydroxide aqueous solution.

(b(ii))[1]

Give the formula of the ion that is responsible for making the solution alkaline.

(c(i))[1]

Name the gas for which limewater is used as a test.

(c(ii))[2]

Suggest what the term saturated solution means.

(c(iii))[2]

Describe how you would prepare a sample of limewater from solid calcium hydroxide.

(c(iv))[3]

Describe how you would test for calcium ions in a sample of limewater.\n\ntest method\n\nobservations made

(d(i))[1]

Name the apparatus used to measure the acid volume in this titration.

(d(ii))[1]

State the type of reaction that occurs.

(d(iii))[1]

Besides limewater and dilute hydrochloric acid, state what other kind of substance must be added to the conical flask.

(d(iv))[5]

Calculate the number of moles present in $20.0\,\text{cm}^3$ of $0.0500\,\text{mol dm}^{-3}$ HCl. Determine the number of moles of Ca(OH)$_2$ in $25.0\,\text{cm}^3$ of the limewater. Calculate the concentration of Ca(OH)$_2$ in $\text{mol dm}^{-3}$. Determine the concentration of Ca(OH)$_2$ in $\text{g dm}^{-3}$.

Worked solution & mark scheme

This 21-mark question has a full step-by-step worked solution and mark scheme. One marking point: H2 is identified as the product

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