Hey, can you help me on this last question. I don't understand how I can figure it ouyt without any indicators or solutions. Please help!
13. Three solutions labelled A, B, and C are known to have pH values of 4.0, 6.5, and 8.0. Write an experimental design including diagnostic tests with only two indicators to identify the pH of all three solutions.
Thanks!
Find an acid indicator that show pH 5 and below. Find a base indictor that shows 7 and above.
Those two indicators will test for all the given pHs...think on it.
http://www.constructionwork.com/resources_details_1285ph_indicators.html?PHPSESSID=c2794a72bc79c213a1fb30436dea22e5
To identify the pH values of the three solutions using only two indicators, you will need an acid indicator that shows a color change at pH 5 and below, and a base indicator that shows a color change at pH 7 and above.
First, find an acid indicator that changes color when the pH is 5 and below. Litmus paper is a commonly used acid indicator that turns red in acidic conditions and stays blue in basic conditions. So, you can use litmus paper to test if a solution is acidic.
Next, find a base indicator that changes color when the pH is 7 and above. Phenolphthalein is a widely used base indicator that is colorless in acidic solutions and turns pink in basic solutions. So, phenolphthalein can be used to test if a solution is basic.
Now, to design the experiments, follow these steps for each solution:
1. Dip a piece of litmus paper into a sample of the solution.
2. Observe the color change of the litmus paper.
- If the litmus paper turns red, the solution is acidic (pH 5 or below).
- If the litmus paper remains blue, the solution is not acidic (pH above 5).
3. If the litmus paper turns red, it indicates that the solution is acidic. Perform the next test using phenolphthalein.
4. Add a few drops of phenolphthalein to the solution.
5. Observe the color change of the solution.
- If the solution turns pink, it is basic (pH 7 or above).
- If the solution remains colorless, it is not basic (pH below 7).
By following these steps, you can identify the pH of all three solutions using just two indicators.