pH / pOH Lab (Honors)

Purpose (put into lab book)

• The purpose of this lab is to examine the pH of various household products and then calculate the [H+], pOH, and [OH-].

Practice (put into lab book)

• Copy and complete the following chart into your lab book. This will allow you to practice the pH and pOH formulas. The first two rows are easy and you should complete them without the use of your calculator. The next four rows are harder and you must use a calculator to complete them. Make sure YOU know how to use your calculator and are not just copying your partners answers. Show formulas and substitution for the bottom four rows.

Hypothesis (put into lab book)

• We are going to be measuring the pH of various household products. Before we do, you are going to guess what you think the pH will be for each of the substances. You can not use the internet for any assistance. Create a chart in your lab book that has a column for the product and a column for your pH guess. The list of products can be found below.

• Products: ammonia, vinegar, tide (laundry detergent), scope (mouthwash), V8, tea, soda, lemon juice, windex (window cleaner), soapy water

• Now that you have guessed the pH for each of the substances, you are going to enter your guess into a form so that we can compare the class data and see which group is closest to the correct pH in the end. Click here to enter your guesses.

Procedure / Data (read, summarize, and create the data table in your notebook)

• 1. You will now be testing the pH of the household products mentioned above.

  2. Create a data table in your lab book that has columns for product name, pH, [H+], pOH, and [OH-].

  3. If you are at a front lab table, you will be testing ammonia, vinegar, tide, scope, and V8 first. You will be testing the pH using pH paper. Place a small amount of the product into the spot plate, dip in the pH paper, and take a reading. Record the value into your chart and calculate the other values without the use of a calculator.

  4. If you are at the back lab table, you will be testing tea, soda, lemon juice, windex, and soapy water first. You will be testing the pH using a pH probe hooked up to logger pro. Dip the pH probe into the product wait about 30 seconds and take a reading. Rinse the probe with water before putting it into a new substance. Record the pH value (do not round the number) and calculate the other values with the use of a calculator.

  5. When you are done at your table, you will be switching places with a group at the other set of tables (front tables switch with back tables and vice versa).

Click here if you're absent to see pictures from lab. Be sure to fill out the guess column before clicking to see the pictures from lab.

Conclusion (answer in your lab book)

• 1. List all of the acidic household products in order from strongest to weakest.

  2. What do all of the acidic items have in common?

  3. List any neutral items.

  4. List all of the basic household products in order from strongest to weakest.

5. What do all of the basic items have in common?