Given the information for the test procedure, try to write the net ionic equatio

Question

Given the information for the test procedure, try to write the net ionic equation for the key reation in each test.

SO32-: Sulfite ion in acid solution tends to evolve SO2, which can be detected by its odor even at low concentrations. Sulfite ion is slowly oxidized to sulfate in moist air, so sulfite-containing solutions will usually test positive for sulfate ion.

To 1 mL 0.5 M Na2SO3 add 1 mL 6 M HCl, and mix with your stirring rod. Cautiously, sniff the rod to try to detect the acrid odor of SO2, which is a good test for sulfite. If the odor is too faint to detect, put the test tube in the hot water bath for 10 seconds and sniff again.

To proceed with a chemical test, add 1 mL 1M BaCl2 to the solution in the tube. Stir, and centrifuge out any precipitate of BaSO4. Decant the clear solution into a test tube and add 1 mL 3% H2O2, hydrogen peroxide. Stir the solution and let it stand for a few seconds. If sulfite is present, its oxidation to sulfate will cause a precipitate of BaSO4 to form.

If thiocyanate is present, it may interfere with this chemical test. In that case, add 1 mL 1 M BaCl2 to 1 mL of the sample. Centrifuge out any precipitate, which will contain BaSO3 if sulfite is present, but will not contain thiocyanate. Was the solid with 2 mL water, stir, centrifuge, and discard the wash. To the precipitate add 1 mL 6 M HCl and 2 mL water, and stir. Centrifuge out any BaSO4, and decant the clear liquid into a test tube. To the liquid add 1 mL 3% H2O2. If you have sulfite present, you will observe a new precipitate of BaSO4 within a few seconds.

Explanation / Answer

Na2SO3(aq) + 2HCl(aq) -----> 2NaCl(aq) + H2O(l) + SO2(g)

Na2SO3(aq) + H2O2(aq) ------> Na2SO4(aq) + H2O(l)

Na2SO4(aq) + BaCl2(aq) -------> BaSO4(s) + 2NaCl(aq)

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.