What is the major organic product of 1-hexyne with 2 moles of HCl?

1st - its a buffer so calculate its pH there are more than one way of doing this:

Ka = [CH3COO-][H+]/[CH3COOH] (Ka is 1.76 x 10–5 need to know or be given this)

assume acid conc at eqm is same as at start and the same for the ethanoate ion

so 1.74 x 10–5= 0.2[H+]/0.2 = 1.74 x 10–5

pH = -log 1.74x10–5 = 4.76

2nd the effect of adding HCl

H+ ions will react with ethanoate ions forming CH3COOH

so if we neglect the volume of the HCl you added and assume it is small so the total vol is still 1litre

an extra 0.05 mol of ethanoic acid will form and the ethanoate ion will drop by 0.05mol

so now 1.74x10–5 = 0.15[H+]/0.25

so [H+] = 1.74x10–5x0.25/0.15 = 2.9 x 10–5

so pH = 4.54

The pH has not gone down by much - not surprising its a buffer!

You could try calculating what the effect would be on adding the HCl to 1 L containing 0.2 mol of CH3COOH alone (not a buffer) the answer will be a much lower pH - I don’t have time to do it now but will edit this later to give an answer.

Time to answer now

Adding HCl is the same as adding 0.05 mol of H+ as it is completely disossociated - a strong acid. Neglecting the fact a few H+ ions will be present from the acetic acid (though not many as the ethanoate ions will react with the added H+ to form acetic acid). The concentration of the H+ would be 0.05 mol/L

pH would therefore be -log 0.05 = 1.30

which is massively lower than 4.54 as it is not a buffer solution.

The equation is:

CH3-CH2-CH2-CH2-C≡CH + 2HCl → CH3-CH2-CH2-CH2-CCl2-CH3

The product is 2,2 dichlorohexane

1mol 1-hexyne reacts with 2 mol HCl to produce 1 mol 2,2-dichlorohexane. This addition reaction follows Markovnikov’s rule - the 2Cl- add to the highest substituted C atom