What is the pH of 1 part vinegar plus 9 parts water?

Vinegar typically has a pH of around 2.5, while water has a neutral pH of 7. When you dilute 1 part vinegar with 9 parts water, the resulting mixture's pH will increase, likely falling between 3 and 4, depending on the specific concentration of acetic acid in the vinegar. This is still acidic, but significantly less so than undiluted vinegar.