Acids and Bases and pH Measurement
Some common household products are aqueous solutions of acids or bases.
You will measure the acidity of various chemicals is your home. You
will determine the pH of household solutions with pH indicator paper.
Many plant pigments are altered by the amount of acid or base in
solutions. The changes that occur in the plant pigments affect the
light absorbing properties of these molecules. Certain molecules will
absorb different wavelengths of light depending on the hydronium ion
concentration in the solution. Different colors are displayed as a
function of the wavelength. Thus different hydronium ion concentrations
result in different colors. If the plant pigment is applied to special
paper, when that paper is contacted with hydronium ions it will change
color.
Acidity and alkalinity are a measure of the hydronium ions in solution.
More hydronium ions, the more acidic the solution; fewer hydonium ions,
the less acidic or more alkaline (same as more basic) will be the
solution. An easy way to check hydronium ions is by measuring the pH of
the solution. Since pure water has a pH of 7, any solution with a pH
less than 7 is an acid, and any solution with a pH of greater than 7 is
a base.
Safety Guidelines
Wear safety goggles
Some common household products are strong acids or strong bases; be
careful not to get them on your skin.
Wash your hands after this experiment.
Materials
Strips of pH indicator paper and pH color chart
Several 1 oz plastic cups to hold household liquids
Paper towels
Several household liquids for testing. Suggestions include:
Coffee
Soft drinks
Fruit juices
water
Window cleaner
Dishwashing detergents
Soaps or detergents
Shampoo
Antacids
Vinegar
Ammonia
Procedure
Pour a very small amount of liquid product into the plastic cups.
Take a fresh strip of pH paper and dip it into the liquid.
Observe the color change.
Compare the color change while the paper is still wet to that of the
color chart on the pH indicator container.
Record the pH.
Keep track of all the products you test and their pH.
Your setup may look like the following:
Be certain to use a fresh pH indicator strip with each solution. Be
careful not to contaminate the pH paper with solutions on your fingers.
Use paper towels to wipe up spills and keep your fingers dry.
Questions
From your list of products and their pH arrange them in order of
increasing pH.
What was your most acidic product?
What was your most basic product?
Were their any products for which you could not detect a change of color
in the pH paper? What can you conclude from this?
Can you determine any trends in the acidic or basic products?
Chemistry Homework Solutions
#50001
ph experiment
Acids and Bases and pH Measurement
Some common household products are aqueous solutions of acids or bases. You will measure the acidity of various chemicals is your home. You will determine the pH of household solutions with pH indicator paper.
Many plant pigments are altered by the amount of acid or base in solutions. The changes that occur in the plant pigments affect the light absorbing properties of these molecules. Certain molecules will absorb different wavelengths of light depending on the hydronium ion concentration in the solution. Different colors are displayed as a function of the wavelength. Thus different hydronium ion concentrations result in different colors. If the plant pigment is applied to special paper, when that paper is contacted with hydronium ions it will change color.
Acidity and alkalinity are a measure of the hydronium ions in solution. More hydronium ions, the more acidic the solution; fewer hydonium ions, the less acidic or more alkaline (same as more basic) will be the solution. An easy way to check hydronium ions is by measuring the pH of the solution. Since pure water has a pH of 7, any solution with a pH less than 7 is an acid, and any solution with a pH of greater than 7 is a base.
Safety Guidelines
- Wear safety goggles
- Some common household products are strong acids or strong bases; be careful not to get them on your skin.
- Wash your hands after this experiment.
Materials
Strips of pH indicator paper and pH color chart
Several 1 oz plastic cups to hold household liquids
Paper towels
Several household liquids for testing. Suggestions include:
Coffee
Soft drinks
Fruit juices
water
Window cleaner
Dishwashing detergents
Soaps or detergents
Shampoo
Antacids
Vinegar
Ammonia
Procedure
1. Pour a very small amount of liquid product into the plastic cups.
2. Take a fresh strip of pH paper and dip it into the liquid.
3. Observe the color change.
4. Compare the color change while the paper is still wet to that of the color chart on the pH indicator container.
5. Record the pH.
6. Keep track of all the products you test and their pH.
7. Your setup may look like the following:
8. Be certain to use a fresh pH indicator strip with each solution. Be careful not to contaminate the pH paper with solutions on your fingers.
9. Use paper towels to wipe up spills and keep your fingers dry.
Questions
1. From your list of products and their pH arrange them in order of increasing pH.
2. What was your most acidic product?
3. What was your most basic product?
4. Were their any products for which you could not detect a change of color in the pH paper? What can you conclude from this?
5. Can you determine any trends in the acidic or basic products?
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