Which method would be most effective for testing the pH of a common household liquid that is suspected to be acidic, such as vinegar?

The easiest and most reliable way for a home experiment is to use pH test strips or paper, which change color when dipped into the liquid. These strips are calibrated to show a range of pH values, so you can match the color on the strip’s chart to estimate the pH. For vinegar, the color will typically match a pH of about 2–3, confirming its acidity. A simple example is dipping a strip into a cup of vinegar, waiting a few seconds, and comparing the resulting color to the chart; if it matches the “2” spot, the vinegar is indeed acidic. This method is quick, inexpensive, and safe for everyday use.