Chapter 2 Homework problems

4. What is the pH of a solution that has an H+ concentration of (a) 1.75 × 10-5 mol/L; (b) 6.50 × 10-10 mol/L; (c) 1.0 × 10-4 mol/L; (d) 1.50 × 10-5 mol/L?

-log(H+ molarity) = pH A.4.76 b.9.19 c. 4.0 d.4.82

16. *PIC*The components of poison ivy and poison oak that produce the characteristic itchy rash are catechols substituted with long-chain alkyl groups. If you were exposed to poison ivy, which of the treatments below would you apply to the affected area? Justify your choice. (a) Wash the area with cold water. (b) Wash the area with dilute vinegar or lemon juice. (c) Wash the area with soap and water. (d) Wash the area with soap, water, and baking soda (sodium bicarbonate)

Bicarbonate, a weak base , titrates -OH to O-, making the compound more polar and more water solubule *NEED HELP*

2. The interactions between biomolecules are often stabilized by weak interactions such as hydrogen bonds, how might this be an advantage to the organism?

Bio-molecular interactions generally need to be reversible; weak interactions allow reversibility

3. Explain why ethanol (CH3CH2OH) is more soluble in water than is ethane(CH3CH3)

Ethanol is polar Ethane is not. The ethanol -OH group can hydrogen bond with water

11. (a) Does a strong acid have a greater or lesser tendency to lose its proton than a weak acid? (b) Does the strong acid have a higher or lower Ka than the weak acid? (c) Does the strong acid have a higher or lower pKa than the weak acid?

a) strong acid has a greater tendency to lose its proton then a weak acid b.A strong acid has a higher Ka than the weak acid c.A strong acid has a lower pKA than an weak acid

7. (a) Write out the acid dissociation reaction for hydrochloric acid. (b) Calculate the pH of a solution of 5.0 × 10-4 M HCl. (c) Write out the acid dissociation reaction for sodium hydroxide. (d) Calculate the pH of a solution of 7.0 × 10-5 M NaOH.

a. HCL <> H+ + Cl- b.3.3 c.NaOH <> Na+ + OH- D. 9.8 Part D explain find pOH pOH=-log(OH concentration) 14-pOH= pH

13. Which is the conjugate base in each of the pairs below? (a) RCOOH, RCOO− (b) H2PO4−,H3PO4 (c) RNH2,RNH3+ (d) H 2 CO 3 , HCO − 3

a. RCOO- B. H2PO4- C. RNH2 D.HCO-3

5. What is the H+ concentration of a solution with pH of (a) 3.82; (b) 6.52; (c) 11.11?

h+ concentration= 10^(-pH) a.1.51 x 10^-4 b.3.02 x 10^-7 c. 7.76 x 10^-12