CHEMISTRY TEST XI S2 2009

1. Hydrogen bromide gas is dissolved into water. Explain the acid base theories according to Arrhenius, Bronsted-Lowry, and Lewis.

2. Which of the following 0.1 M solutions has the lowest pH and which has the highest pH?
a. BaCl2(aq)
b. HCl(aq)
c. NH3(aq)
d. CH3COOH(aq)
e. NaOH(aq)
f. CH3OH(aq)

3. The following data were collected by a student performing an acid-base titration:
· Volume of the acid,HCl = 25.0 mL
· Molarity of the acid = 0.10 M
· Volume of the base,NaOH= 20.0mL
From the collected data, calculate the concentration of the base.
4. Draw the titration curve of weak acid and strong base. Predict the pH of :
a. initial point (before titration)
b. pH before equivalent point
c. at equivalent point
d. after equivalent point.

5. What is the pH of 50.0 mL of 0,10 M CH3COOH (Ka = 2,0 x 10-5) after 25.0 mL of 0,10 M NaOH have been added? (log2 = 0,3)

6. What is the pH of 10.0 mL of 0,10 M CH3COOH (Ka = 2,0 x 10-5) after 10.0 mL of 0,10 M NaOH have been added? (log2 = 0,3)

7. Which condition is essential to prepare a saturated solution of an ionic salt? Explain the reason.

8. Write down the Ksp expression for a saturated solution of Ba3(PO4)2.

9. If the solubility of Pb(OH)2 is 0.155g/L (Mr=310), calculate the concentration of each ion in a saturated solution of Pb(OH)2.

10. What is the pH of a saturation solution of Zn(OH)2 if it has a solubility of 10-7 mol/L?

11. The [OH-] is measured to be 3 x 10-3 M in a 100 mL sample of saturated solution of Al(OH)3. Calculate the solubility of Al(OH)3.

12. A student evaporated 200.0 mL of a saturated solution of SrCrO4 to dryness. The residue contained 1.2 x 10-3 mol SrCrO4. Calculate the solubility of SrCrO4.

13. When equal volumes of 0.00001 M AgNO3 and 0.00001 M CaCl2 are mixed, calculate the trial ion product (quotient, Qc) and predict there is a precipitation or not. (Ksp AgCl = 1,1 x 10-10)

14. Consider the following equilibrium: AgCl(s) ⇄ Ag+(aq) + Cl-(aq)
Sodium chloride is added to a saturated solution of AgCl. Explain how about he amount of solid AgCl.

15. What is the maximum [Mn2+] possible in a 0.10 M NaOH solution? Ksp Mn(OH)2 = 5 x 10-13

16. Explain the type of the following colloids.
a. smoke d. gelatin
b. milk e. paint
c. butter

17. Oil and water can not mix each other. Explain the reason.

18. Explain the following properties of colloid.
a. coagulation
b. electrophoresis
c. dialysis

19. Choose which electrolyte can be used to coagulate fastly a negative and a positive colloids. Explain the reason.
a. NaCl(aq) d. CaCl2(aq)
b. AlCl3(aq) e. Na2SO4(aq)
c. Na3PO4(aq)

20. Explain the method to make the following colloids.
a. gold sol from solid
b. paint from solid
c. AgCl sol from solution
d. sulfur sol from SO2 gas