(a) An aqueous solution of a salt was added to excess sodium sodium trioxocarbonate (IV) solution in a test tube. There was effervescence, the test tube became warm and a white precipitate was observed. State three inferences that could be drawn from these observations.
(b) Consider the following salts; NH\(_4\)Cl; PbSO\(_4\); NaHCO\(_3\) and Cu(NO\(_3\))\(_2\).
Select from the list, the salt(s) which:
(i) would not readily dissolve in water;
(ii)produce(s) effervescence with dilute mineral acids;
(iii) decompose(s) on heating;
(iv) dissolve(s) in water to form an alkaline solution;
(v) sublime(s) on heating
(c) A solution of an acid was titrated with sodium hydroxide solution using methylorange as the indicator. State three precautions that are necessary when carrying out such an experiment.
a(i) Salt solution is acidic
- Reaction is exothermic.
- White precipitate is likely to be a trioxocarbonate(IV) salt of Al, Ca and Zn.
- Prepared solution contained soluble salt of Al, Ca and Zn.
b(i)PbSO\(_4\)
(ii) NaHCO\(_3\)
(iii) NaHCO\(_3\) ; Cu(NO\(_3\))\(_2\).
(iv) NaHCO\(_3\)
(v) NH\(_4\)Cl
(c) Precautions to be taken during titration include:
- Wear a lab coat to protect your clothing from spills.
- Ensure to rinse the burette with an acid solution
- Also ensure the funnel is removed immediately after filling the acid into the burette.
- Avoid error due to parallax while taking the reading to determine the end point.
- Ensure all glassware is clean and free of bubbles.
a(i) Salt solution is acidic
- Reaction is exothermic.
- White precipitate is likely to be a trioxocarbonate(IV) salt of Al, Ca and Zn.
- Prepared solution contained soluble salt of Al, Ca and Zn.
b(i)PbSO\(_4\)
(ii) NaHCO\(_3\)
(iii) NaHCO\(_3\) ; Cu(NO\(_3\))\(_2\).
(iv) NaHCO\(_3\)
(v) NH\(_4\)Cl
(c) Precautions to be taken during titration include:
- Wear a lab coat to protect your clothing from spills.
- Ensure to rinse the burette with an acid solution
- Also ensure the funnel is removed immediately after filling the acid into the burette.
- Avoid error due to parallax while taking the reading to determine the end point.
- Ensure all glassware is clean and free of bubbles.
