Other alkaline solutions
4 marks · NormalSome cleaning products are described as 'alkaline'.
Ammonia is commonly found in cleaning products. State the ions that are produced when ammonia reacts with water.
Explain why solutions of ammonia are described as alkaline.
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(a) NH_4^+ and OH^- · must show ammonium ions (NH_4^+), hydroxide ions (OH^-)
(b) Solutions are alkaline because ammonia in water produces hydroxide ions (OH^-), which cause alkalinity. · must show hydroxide ions produced, alkalinity due to OH^-
Common mistakes: Stating ammonia produces only ammonium ions, omitting hydroxide ions
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Marking points
B1 (a) · 1 mark · Names ammonium ion: NH_4^+.
B1 (a) · 1 mark · Names hydroxide ion: OH^-.
M1 (b) · 1 mark · Mentions OH^- produced (reason for alkalinity).
A1 (b) · 1 mark · Links alkalinity to the presence of hydroxide ions.
Worked solution
a) Ammonia reacts with water to form ammonium ions (NH_4^+) and hydroxide ions (OH^-).
b) The solution is described as alkaline because the hydroxide ions (OH^-) produced make it alkaline.