Lab 4 Acids & Bases

Total: /25 marks In this investigation, you will be making predictions about whether substances are acidic, basic or neutral based on the prop erties discussed in our previous lesson on acids and bases. You will then be using different pH indicators to test your hypotheses. Record your results in the observation table below. Include space for your solutions, your prediction, and the results of each indicator test Solutions to be tested: drain cleaner, vinegar, tide, sprite, salt water Indicators : phenolphthalein, cabbage juice, red litmus paper, blue litmus paper, pH paper & a mystery indicator . Procedure : Gather a spot plate. 1. Place the spot plate vertically over a piece of paper. Using the paper, label the columns by the names of indicators. Label the rows as the types of solutions. (Red and blue litmus paper can be tested in the same column) 2. Place 3 drops of each solution in each well in the appropriate row. 3. Place 2 drops of each indicator in each well in the appropriate column. Record your results. 4. Wash and dry your spot plate thoroughly before using new substances in wells. (To wash your spot plate use the squirt bottle provided and clean into the waste beaker). 5. Part One Observations: Part One: /5 marks In this section, you will record your observations for each of the following tests. You will conduct the Vernier Probe test LAST. Table 1. ________________________________________________________________________________ (give detailed title) Indicators: & Solutions: Predictions (acid/base) Phenolphthalein Mystery Indicator Red cabbage juice Red litmus paper Blue litmus paper pH Paper/ Universal Indicator Diluted Bleach Vinegar Tide Sprite Ocean Water (saline) Using the following pH indicator colour charts, classify each of the solutions that you tested as an acid or a base. Solution: Result (acid/base) Diluted Bleach Vinegar Tide Sprite Lab 4: Acids & Bases Thursday, October 28, 2021 1:07 PM Chemistry Page 1

Sprite Ocean Water (saline) Part Two: Vernier Probe Test Verification Part Two: /5 marks Using the Vernier pH probes, verify your results from above. Solution Predictions (acid/base) Measured pH (Vernier Probe) Result (acid/base) Diluted Bleach Vinegar Tide Sprite Ocean Water (saline) Discussion & Analysis: Discussion & Analysis: /10 marks Answer the following questions in complete sentences: Based on your observations, which substances were acidic? Which were basic? Which were neutral? (3 marks) 1. Based on my observations, the substances that were acidic were, vinegar, sprite, and tide. The basic ones were diluted bleach, and saline. The most neutral based on my observations was diluted bleach. Did you find certain indicators to be more useful for identifying acids? Alternatively, did you find certain indicators to be more useful for identifying bases? If so, please explain. (2 marks) 2. When I was identifying acids and bases there was different indicators that helped find each one more easily. With acids it was easier to identify them with the observation page and checking with mixing different chemicals. And with bases it was much easier to find them with the pH vernier probes. Your mystery indicator has a specific colour range. Using the information in your observations chart, and the pH indicator colour charts as a reference, colour in the pH indicator chart for your mystery indicator below . (2 marks) 3. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 acidic neutral basic BONUS POINT: Can you identify the pH indicator? ________________________________ Mr. Gate has been complaining (a lot) about heartburn recently. When he consulted Mr. Turley he replied brusquely "lay off the coffee, bud." Perplexed by this Mr. Gate did some research (asked Mr. Chan) and found out that an acidic diet is a key contributor to heartburn. If Mr. Gate wants to measure the pH of coffee, which of the pH indicators above would be the best to use? Remember, coffee naturally has a very dark brown colour. (3 marks) 4. I would say that Red or Blue litmus paper is the best option, I think this because it is easiest to use and best to get the right results. It is easy because you can quickly dip the paper in for a few seconds and see the colour that it changes to. t This fact that this is coloured paper helps as it doesn't get affected as much as a clear liquid would or even clear paper. Overall I believe that the best option is the Blue litmus paper out of the two as it is darker coloured and that help that the colour of the coffee is so dark. Conclusion: Conclusion: /5 marks Chemistry Page 2