Question

2. Below is a brief outline of a method used in preparing lead chloride. Lead carbonate is added to warm dilute nitric acid: When the carbonate has reacted with the warm acid, more carbonate is added until the carbonate is inexcess. The mixture is filtered. Some sodium chloride solution is added to the filtrate. (a) (i) What observations are made when lead carbonate is added to the warm nitric acid? (ii) Explain why warm nitric acid is used. (d) (iii) What happens when sodium chloride is added to the filtrate? (b) Write an equation for the reaction between: (i) The carbonate and the acid. (ii) The filtrate and sodium chloride. (c) Write an ionic equation for the reaction in b (ii). Name the reaction that takes place between the filtrate and sodium chloride.​

Answer 1

(a) (i) When lead carbonate is added to warm nitric acid, the following observations are made:

Effervescence occurs, indicating the release of a gas.

Bubbles of gas are evolved, which is carbon dioxide (CO2).

The mixture may also become warm due to the exothermic nature of the reaction.

(ii) Warm nitric acid is used because it enhances the reaction rate. Increasing the temperature of the reaction mixture provides more energy to the particles, leading to increased collision frequency and greater chances of successful collisions between reactant particles. This accelerates the reaction between lead carbonate and nitric acid.

(d) (iii) When sodium chloride is added to the filtrate, the following happens:

A white precipitate of lead chloride (PbCl2) forms. This indicates the reaction between the lead ions from the filtrate and chloride ions from the sodium chloride solution, resulting in the formation of insoluble lead chloride.

(b) The equations for the reactions are as follows:

(i) The reaction between lead carbonate and nitric acid:

PbCO3 + 2HNO3 → Pb(NO3)2 + CO2 + H2O

(ii) The reaction between the filtrate (containing lead nitrate) and sodium chloride:

Pb(NO3)2 + 2NaCl → PbCl2 + 2NaNO3

(c) The ionic equation for the reaction in (b) (ii) is:

Pb2+ + 2Cl- → PbCl2

The reaction that takes place between the filtrate and sodium chloride is a precipitation reaction, where lead chloride precipitates out as a solid.

Answer 2

(a) (i): bubbles since the carbonate will dissolve to form lead nitrate, carbon(iv) oxide and water. the solution becomes warm to the touch

(ii): To increase the rate of the reaction since it speeds up the formation of the ions that react with the lead carbonate

(d) (iii):Lead nitrate will react witg sodium chloride to form lead chloride and sodium nitrate.Lead chloride will precipitate out of the reaction. PbCO3(s) + 2HNO3(aq) → Pb(NO3)2(aq) + CO2(g) + H2O(l).

The balanced equation for the reaction between lead(II) nitrate and sodium chloride chloride is Pb(NO3)2(aq) + 2NaCl(aq) → PbCl2(s) + 2NaNO3(aq).

ionic equation:2NO3-(aq) + Pb2+(aq) + 2Cl-(aq) → PbCl2(s) + 2Na+(aq) + 2NO3-(aq).

Double displacement reaction (the reaction that takes place between the filtrate and sodium chloride)