(a) State what would be observed when:
(i) Chlorine is passed through a freshly prepared solution of FeCl\(_2\).
(ii) SO\(_2\) is bubbled into a solution of FeCl\(_3\);
(iii) A few drops of water Is added to sodium hydroxide pellets in a test tube;
(iv) Dilute H\(_2\)SO\(_4\) is added to CaCO\(_{3(s)}\)
(b) Three test tubes contain solutions of SO\(_3^{2-}\), CO\(^{2-}_3\) and SO\(_4^{2-}\) respectively. Describe one chemical method that you would use to identify the solution containing SO\(_4^{2-}\)
(c)(i) Draw and label a diagram to illustrate the separation of a mixture of petrol and water
(ii) Which of the following will dissolve faster? 10g of NaOH pellets in 100 cm\(^3\) of water; 10g of NaOH powder in 50 cm\(^3\) of water. Give the reason for your answer.
Explanation
(a)(i) The chlorine turns green colour of FeCl\(_2\) to brown FeCl\(_3\)
(ii) SO\(_2\) turns brown colour of FeCl\(_3\) to green FeCl\(_2\)
(iii) The test tube will be warm.
(iv) When dilute H\(_2\)SO\(_4\) is added to CaCO\(_3\), Effervescence occurs and CO\(_2\) is evolved
(b) Add barium chloride (BaCl\(_2\)) to each test tube, white precipitate of SO\(_4^{2-}\), SO\(^{2-}{3}\) and CO\(_3^{2-}\) will be formed. Add HCl\(_{(aq)}\), the precipitate of CO\(_3^{2-}\) and SO\(_4^{2-}\) will dissolve while the white precipitate of CO\(_3^{2-}\) will be insoluble.
(c)(i)
(ii) 10g of NaOH powder in 50cm\(^3\) of water will dissolve faster because NaOH powder has a large surface area than the NaOH pellets.