Quiz: Chemical Properties of Consumer Products

1. A commercial bottled water claims to be “salt free”. What tests could be used to test this claim and what should you see as a result? Write equation showing the reaction.

The salt present in the commercial bottles water is NaCl. To test for Na+

Flame test: color of sodium is golden yellow. Test for Cl-

AgNO3 (aq)+Cl-(aq) → AgCl(s) White ppt

If the water is salt free these tests should give negative results.

2. Carbon dioxide is expelled during normal breathing. How could you test for the presence of this gas in the breath? What would you see? Write equation showing the reaction.

CO2 when reacts with water produces H2CO3. H2CO3 reacts with Ba(OH)2 to give BACO3 white ppt.

CO2(g)+H2O(l) → H2CO3(Aq)

H2CO2 (aq) + Ba(OH)2 → BaCO3 (s) White ppt

If the out is collected and dissolved in water and then reacted with Ba(OH)2, white precipitate should be observed.

3. The label on a box of detergent was faded and unreadable. How could the user determine whether the contents were “phosphate free?” What will the color of the resultant solution?

The presence for phosphate anion is detected using ammonium molybdate in acid solution. It gives bright yellow precipitate.

4. A commercial cleaner for windows contains ammonia. How could you test for its presence?

Ammonia solution when heated produces ammonia gas which turns red litmus blue. Ammonia gas can also be identified by its characteristic strong irritating odor. Aqueous ammonia solution is NH4OH solution.

NH4OH(aq) → NH3(g)+H2O(l)

NH3(g) → red litmus blue

5. Baking soda, sodium bicarbonate, NaHCO3, is used to produce “rising action” in the dough for baked goods. When mixed with an acidic material, such as lemon juice, a gas is given off that is trapped in the dough and results in the “rising action”. Write an equation that shows what happens to this salt when it is stirred with the lemon juice in the mixing bowl. What brings about the “rising action in the dough?

Baking soda is NaHCO3, when lemon juice or any acid is added to it CO2 gas is produced, that brings the rising action in the dough.

HCO3-(aq) +H+(aq) → CO2(g) + H2O(l)