Transcript Activity 46: Investigating Solutions of Acids and Bases

Activity 43 Follow-up
• Flocculate- To add chemicals into
water to mix with and pull together the
contaminants into large clumps
• Sediment- The clumps formed by
flocculation that sink to the bottom of
the water
• Sedimentation- The process of letting
the clumps formed by flocculation sink
to the bottom of the water
Cleaning the Water at a WaterTreatment Plant
Where does our water come from?
The Water Authority delivers water to the 23 retail water
agencies that in turn deliver water to their retail
customers.
Existing Water Resources Within
SDCWA
Activity 43 Analysis
1. What do you know about the source of
your community’s drinking water?
– Comes from Northern California via the
California Aqueduct and the Colorado
River Aqueduct
2. Do you think there are other
communities that might contribute
contaminants to your water source or
get their water from the same source?
– Most of our water supply is surface water
which is supplied from many rivers and
streams
– See earlier map
3. Look at the map below, and find the Great
Lakes. Why do you think the United States
and Canada cooperate to keep the Great
Lakes clean?
– The Great Lakes are bordered by both the
United States and Canada.
– Both use water from the lakes
– Both have communities and industries located
on the lakes
– For these reasons, both want to be able to get
clean water from the lakes and work together
to be sure that neither is polluting them
4. The reading describes two chemicals that are
used to remove contaminants from drinking
water. What are these chemicals, and what is the
purpose of each one?
–
–
Aluminum sulfate or other chemicals are used to
coagulate and remove dirt and other contaminants
Chlorine is used to kill biological contaminants
5. Which water source would you expect to be
more likely to become contaminated by
pesticides---surface water or groundwater?
Explain why you think that.
–
–
Surface water is more open to the environment
People can dump things into it and cause
contamination
Activity 46
Title: Investigating Solutions
of Acids and Bases
What do you know about
acids and bases?
• Acidic or basic water outside of a specific pH
range violates federal standards for drinking
water.
• Higher pH = more basic
• Lower pH = more acidic
• Neutral pH = 7
• Federal water-quality standards require testing
for pH, because water with a high or low pH can
corrode pipes and release harmful metals from
the pipes into drinking water.
Read C-82
Problem: How can solutions be tested to
identify them as acidic, basic, or neutral?
Initial Thoughts/Hypothesis:
In this activity you will…
• Work with several acid-base indicators:
– Universal Indicator
– Phenolphthalein
– pH paper
• An indicator is a substance used to
detect the presence of specific kinds of
chemicals.
Background:
Indicator
Acid
Base
Neutral
Phenolphthalein Colorless
Bright Pink
Colorless
Universal
Indicator
Red or Pink
Blue
Green
pH Paper
Red or
Orange-Red
Blue or Purple
Yellow-Green
Procedure:
Follow procedure on pgs. C-83 to C-85
A data table will be provided for you.
Discuss procedure step #2 with your group.
Don’t write your plan in your notebook.
DO NOT GLUE YOUR TABLES IN YET!
Data/Observation:
Table 1: Indicator Test
Liquid
Indicator
Phenolphthalein Universal
Indicator
Water from the sink
Hydrochloric Acid
Potassium Hydroxide
Rubbing Alcohol
Milk
Lemon Juice
Household Ammonia
Baking Soda in Water
Sprite
White Vinegar
pH paper
You have 3 substances to test with 3 different
indicators. How will you set up your tray?
Hydrochloric Acid
(HCl)
Phen
HCl
U.I.
KOH
HpH
2O
Phenolphthalein
Potassium
Hydroxide (KOH)
Phen
HCl
U.I.
KOH
HpH
2O
Universal Indicator
Water from the
Sink
Phen
HCl
U.I.
KOH
pH Paper
HpH
2O
Demo:
• Water
Neutral
• Hydrochloric Acid (HCl)
Acidic
• Potassium Hydroxide (KOH)
Basic
• Lemon juice
Acidic
• Test the other solutions and compare.
Part B
• What do you think will happen to the pH
of the acid or base if you dilute it with
water?
– In part B is a serial dilution of HCl and KOH
– Copy the results form the teacher
Table 2: Serial Dilution of 1% HCl Solution
Table 3: Serial Dilution of 1% KOH Solution