HBr is a strong acid, so it will completely dissociate in water according to the following reaction:
HBr (aq) → H+ (aq) + Br- (aq)
This means that the concentration of H+ in solution is equal to the concentration of HBr.
pH is defined as the negative logarithm of the concentration of H+ in solution:
pH = -log[H+]
We can use this equation to calculate the pH of the 0.0650 M solution of HBr:
pH = -log[H+]
pH = -log(0.0650)
Using a calculator, we get:
pH = 1.187
Therefore, the pH of a 0.0650 M solution of HBr is approximately 1.19.