[koreanboba]

I have two questions, and I hope someone can answer them.
I've started on these problems but ended up going in a circle.
I was told that these questions shouldn't be hard, yet...

The enzyme alcohol dehydrogenase catalyzes the oxidation of ethyl alcohol by NAD+ to give acetaldehyde plus NADH and a proton:
CH3CH3OH + NAD+ -> CH3CHO + NADH + H+
The rate of this reaction can be measured by following the change in pH. The reaction is run in 1 mL 10 mM TRIS buffer (Ka = 8.32 * 10^-9) at pH 8.6. If the pH of the reaction solution falls to 8.4 after 10 minutes, what is the rate of alcohol oxidation, expressed as nanomoles of ethanol oxidized per sec per mL of reaction mixture?

There are 10 molecules of regulatory protein Z in a spherical animal cell with diameter 20,000 nm. What is the molar concentration of protein Z in the cell? If the molecular mass of protein Z is 80kD, what is this protein's concentration in mg/mL?