Answer to Question #288812 in Organic Chemistry for Shane

Question

If we dissolve CaCO3 in water, we get the following equilibrium:

CO3^2-(aq)+H2O(l) =HCO3^-(aq) + OH^-(aq)

0.675 grams of calcium carbonate is dissolved in enoughwater to make 500 mL of solution. The MW of CaCO3 is 100 g/mol and the Kb of CO3^2- is 2.1x10^-4.

What is the initial concentration of the carbonate ion?

a. 1.35 x 10^-3

b. 0.0135

c. 6.75 x 10 ^-3

d. 0. 021

What is the equilibrium concentration of the hydroxide ion?

a. 6.477 x 10^-4

b. 1.32 x 10^-3

c. 1.5820 x 10^-3

d. 1.9976 x 10^-3

What is the pOH of the solution?

a. 3.1886

b. 2.8794

c. 2.8008

d. 2.6995

What is the pH of the solution?

a. 11.3005

b. 11.1992

c. 11.1206

d. 10.8114

Answer 1

c. 6.75 x 10 ^-3

a. 6.477 x 10^-4

c. 2.8008

a. 11.3005