chemistry hw 1

Acids, Bases, Redox, Molarity, titration

1. Identify each of the following aqueous solutions as strong or weak, and as acid, base, or salt:

2. Write the balanced molecular equation, the complete ionic equation, and the net ionic equation for the reaction of aqueous nitric acid with solid calcium hydroxide. Remember to include states.

3. A solution is prepared by dissolving 0.325 g of Mg(NO3)2 in water to make 150.0 mL of

solution. What is the molarity of the solution?

4. A 25.0 mL sample of acetonitrile, CH3CN (d = 0.786 mLg ), is dissolved in enough water to

produce 150.0 mL of solution. What is the molarity of acetonitrile in the solution?

5. Folic acid, C19H19N7O6, is important in many biological functions. What mass of folic acid is needed to prepare exactly 10.00 mL of a 0.250 M C19H19N7O6 aqueous solution?

6. A 25.00-mL solution of 0.350 M urea, CO(NH2)2, is diluted to 150.00 mL. What is the new

molarity of the solution?

7. What is the oxidation number of the underlined element in:

a. NaOH c. H2PO4–

b. Na2CO3 d. Cr2O72–

8. For the following oxidation-reduction reactions, indicate which species are reduced and which are oxidized. [These redox reactions are not necessarily balanced—and you don’t need to balance them—just identify the species reduced and the species oxidized.]

a. Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)

b. VO2+(aq) + MnO4–(aq) → VO2+(aq) + Mn2+(aq)

For problems 9 – 13, balance the given redox reactions in acidic solution. For problems 12 and 13 balance the redox reactions in basic solution.

9. S(s) + OCl–(aq) → SO32–(aq) + Cl–(aq)

10. Fe2+(aq) + Cr2O72–(aq) → Fe3+(aq) + Cr3+(aq)

11. S2O32–(aq) + MnO4–(aq) → SO42–(aq) + Mn2+(aq)

12. Fe(OH)3(s) + OCl–(aq) → FeO42–(aq) + Cl–(aq)

13. ClO2(aq) → ClO3–(aq) + Cl–(aq)