Question

how many milliliters of calcium hydroxide are needed to neutralize 75.0 mL of 4.75 M hydrobromic acid?

Answer 1

It all depends upon the strength of the Ca(OH)2 doesn't it?

.........Ca(OH)2 + 2HBr ==> CaBr2 + 2H2O
mols HBr = M x L = 4.75 M x 0.075 L = 0.356
Looking at the coefficients in the balanced equation, mols Ca(OH)2 = 1/2 mols of HBr so mols Ca(OH)2 = 0.356/2 = 0.178
M Ca(OH)2 = mols/L
or L = mols/M. You ave mols but you omitted M from the problem. Substitute that and do the math. Then convert L to mL.