pH

pH indicators: pH indicators are chemical substances that can indicate the approximate pH of a solution via color change. eg : pH paper, universal indicator • pH paper: pH paper is used to check if a solution is acidic, basic or neutral. This is done by dipping a strip of pH paper in a solution of interest and observing the color change. The color of the strip is then compared with the color-coded chart that comes with the pH paper kit. The number associated with the color is the pH reading. 0 2 3 4 5 6 7 8 9 10 11 12 • Universal indicator: Universal indicator is a liquid substance that has one color in acidic solutions and another in basic solutions. Experiments: Part I - Strong Acids Watch the video and complete the following: Step 1. A small amount of a strong acid solution was poured into a test tube. 13 Step 2. A pH paper strip was dipped into the solution. Notice the color change in the pH paper. Step 3. Compare this color produced to the colors on the pH chart. Record the color on the pH chart that is closest to the color of the pH paper. Record the corresponding pH value. Strong Acid Color of the pH paper after dipping in the acid solution R Corresponding pH value HO Step 4. Using the pH value determined in step 3, calculate the [H30+] in the strong acid solution. (Write the equation that you would use and show your work .) [H3Q+] in the strong acid solution = _\-'--------- IB 30+ ] = l (f 0 2