Introduction:
A liquid may be an acid, base, or neutral. The degree
of acidity or basicity can be measured by using the pH
scale. The scale is divided into three areas: Acid (readings
below 7), neutral (reading of 7), and basic (readings
above 7). Each division either increase or decreases the
pH of a substance 10 times. The pH of 5 is ten times more
acidic than a pH of 6. Water has a pH of 7 but when it
mixes with air the suspended materials will either raise
or lower its pH. Acid Rain is an example of this type
of reaction.
Objective:
The student will determine the pH of various substances
and will also determine how some of these substances can
affect the environment.
Materials:
- pH paper and Chart or Indicator Solution
- Paper Towels
- 1 depression plate
- Lemon Juice
- Cola
- Food Samples
- Distilled Water
- Baking Soda
Procedure:
- Usie a spot plate.
- Put 2 drops of each sample in one cell of the spot
plate
- Hypothesize whether the liquid would be acid or base.
- Add 2 drops of Indicator to each sample.
- Record this on the data table below.
- Compare the color of the Indicator with that on the
pH chart.
- Record your observation on the chart below.
- Repeat the procedure with the rest of the slides.
|
ooSampleoo
|
Hypothesis
|
ypH
|
Acidic
|
Basic
|
pNeutralp
|
|
|
|
d |
dd |
|
|
|
|
|
|
dd |
|
|
|
|
|
|
dd dd |
|
|
|
|
|
|
|
|
|
|
|
ssssss
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Analysis:
1. Which of the liquids had the lowest pH ?
2. Which of the liquids had the highest pH?
3. Which of the liquids were closest to being neutral?
4. If the pH of a sample was 3 how many times more acidic
is it than a solution with a pH of 6?
