Question

1.) Calculate the solubility (in M) of cobalt(II) hydroxide, Co(OH)₂(s) in H₂O. K_sp = 1.10×10^-16 at a specific temperature. (in M)

What is the pH of this solution of cobalt(II) hydroxide?

2.) What is the ratio of lactic acid (K_a = 1.37x10^-4) to lactate in a solution with pH =4.45? (WRITE RATIO AS DECIMAL)

3.) A 1.00 L solution contains 18.52  g of nitrous acid, HNO₂.What mass of sodium nitrite, NaNO₂, should be added to it to make a buffer with a pH of 2.76? K_a (HNO₂) = 4.0 × 10^–4.

4,) What is the pH of 0.0850 M Fe(NO₃)₃ (K_a of Fe³⁺ = 3.00x10^-3)? Express your answer to two decimal places.

5.) Calculate the change in pH when 0.310 mol H⁺ is added to 1.00 L of each of the following buffers.

a) a 0.580 M solution of pyridine (py) containing 0.480 M pyH^{+ (CHANGE IN PH?)}

^b) a 0.600 M solution of aniline (an) containing 0.920 M anH^{+ (CHANGE IN PH)}

^6.) How much 10.0 M HNO₃ must be added to 1.00 L of a buffer that is 0.0100 M acetic acid and 0.100 M sodium acetate to reduce the pH to 5.00 ?