Skip to content
MathsGenie logo
Quick links
Open app

Course home

  1. IGCSE
  3. Chemistry Edexcel
  5. Question bank

Acids, bases and salt preparations

Medium
1234567891011121314151617181920212223242526272829303132333435363738394041
Question 39

This question is about the insoluble salt lead(II) bromide.

a.

A student uses the precipitation method to prepare lead(II) bromide.

The equation for the reaction they use is:

Pb(NO3)2(aq)+2NaBr(aq)→PbBr2(s)+2NaNO3(aq) \text{Pb(NO}_3)_2\text{(aq)} + 2\text{NaBr(aq)} \rightarrow \text{PbBr}_2\text{(s)} + 2\text{NaNO}_3\text{(aq)} Pb(NO3​)2​(aq)+2NaBr(aq)→PbBr2​(s)+2NaNO3​(aq)

Describe how they could use solutions of lead(II) nitrate and sodium bromide to obtain a pure, dry sample of lead(II) bromide. Identify two suitable pieces of apparatus they would use to carry out this process.

[6]
b.

The student's teacher uses this apparatus to electrolyse a pure sample of molten lead(II) bromide.

A diagram showing the electrolysis of molten lead(II) bromide.

Observations during the experiment:

  1. A small blob of a silvery liquid appears at one electrode.
  2. An orange-brown vapor forms at the other electrode.
  3. The lamp stops working soon after the teacher stops heating the lead(II) bromide.

Which is the correct statement about this electrolysis?

  • A the orange-brown vapor is bromide ions
  • B the products are both elements
  • C the silvery liquid forms at the positive electrode
  • D the silvery liquid is molten lead(II) bromide
[1]
c.

The student writes this half-equation to show the reaction in which the orange-brown vapor forms:

2Br−+2e−→2Br 2\text{Br}^- + 2\text{e}^- \rightarrow 2\text{Br} 2Br−+2e−→2Br

Identify the two mistakes in their half-equation.

[2]
d.

Explain why the lamp stops working soon after the teacher stops heating the lead(II) bromide.

[2]

Acids, bases and salt preparations Questions

  1. IGCSE
  2. /Chemistry
  3. /Acids, bases and salt preparations