calculate the volume of .1M HCl that is required to react with 50 mL of .1M ammonia to form a mixture that has pH 9

Answer 1

Use the Henderson-Hasselbalch equation but this one takes a little more work than the last one.
Write the equation.
NH3 + HCl ==> NH4Cl

You start with 50 mL x 0.1 M = 5 mmoles and you want to add HCl to it. The easy way to do it is to determine what the ratio Base/acid must be and go from there.

Answer 2

2 C2H2 + 5O2 >>> 4CO2 + 2H2O
In the above equation . How many grams of CO2 are produced when 109.2 grams of C2H2