A student adds sodium hydroxide solution to a solution of iron(II) sulfate. A green precipitate of iron(II) hydroxide, Fe(OH)2\text{Fe(OH)}_2Fe(OH)2, initially forms. When left exposed to the air, the precipitate slowly turns into a reddish-brown solid.
Which statement correctly explains this chemical change?
Iron(II) ions, Fe2+\text{Fe}^{2+}Fe2+, are oxidised to iron(III) ions, Fe3+\text{Fe}^{3+}Fe3+, by losing electrons.
Iron(II) ions, Fe2+\text{Fe}^{2+}Fe2+, are reduced to iron(III) ions, Fe3+\text{Fe}^{3+}Fe3+, by gaining electrons.
Iron(III) ions, Fe3+\text{Fe}^{3+}Fe3+, are oxidised to iron(II) ions, Fe2+\text{Fe}^{2+}Fe2+, by gaining electrons.
Iron(III) ions, Fe3+\text{Fe}^{3+}Fe3+, are reduced to iron(II) ions, Fe2+\text{Fe}^{2+}Fe2+, by losing electrons.
Practise Edexcel GCSE Chemistry Qualitative analysis: tests for ions with exam-style questions for Foundation and Higher tier. 127 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.
