1- the vinegar soltion sold in the store is about 5% acetic acid. Assuming that the solution has a density of 1.01 g/mL, calculate the pH of vinegar.

Answer 1

I assume you know Ka for HAc (acetic acid)
5% vinegar means 5g HAc/100 mL o 50 g HAc/1L. mols HAc = 50g/molar mass or estimated 0.83 mols/L or 0.83M if that percent is w/v.
If mass percent, that is
0.83 mol/1000g solution.
Use density to convert 1000 solution to mL. 1000/1.01 = about 990 and
0.83/0.990 = ?. Slightly different for m/v and m/m(w/w)