At 300.K and 1.00 atm, assume that 25 mL of NO gas reacts with 22 mL of

Question

oxygen gas and excess water to produce nitric acid according to the following
equation:
2NO(g)+(3/2)O2(g)+H2O(l)-->2HNO3(g)
If all of the nitric acid produced by this reaction is dissolved into 25 mL of
water, what would be the pH of the resulting solution?
Hint: before you begin, think about which reactant is the limiting reagent.

Answer 1

I would start by converting 25 mL NO gas to moles with PV = nRT. Do the same for 22 mL O2.
Using the coefficients in the balanced equation, convert moles NO and moles O2 (in two separate operations) to moles HNO3. From the hint, I expect the moles HNO3 from each will NOT be the same which means one of them is wrong. The correct one, in limiting reagent problems, is ALWAYS the smaller value and the material producing that value is the limiting reagent. Remembering that molarity = moles/L, substitute moles HNO3 you have and 0.025 for the 25 mL and that should be the molarity. Convert M to pH remembering that HNO3 is a strong acid (ionizes 100%) and the molarity = (H^+).

Answer 2

Thank you! That was very helpful. My final answer for the pH was 1.39. Is that correct?

Answer 3

yes. I came up with that answer, also.