acids and bases

7/16/2019 Acids and Bases

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Acids and Bases

Target: To distinguish between an acid

and a base

Key Terms: Acid Base

OH- ions Neutral

pH scale H+ ions

Buffer

Task: Working with a partner, youhave two days to complete all five

stations. The stations can be completed in any order. There are more specific

instructions at each station.

Station 1: The pH Scale

Station 2: Brainpop’s Acids and Bases video and quiz –

http://www.brainpop.com.*There is a Spanish version of the video – http://es.brainpop.com.

Station 3: Can Lake Life Remain Despite Acid Rain?

Station 4: Quia’s The pH scale – www.quia.com/rd/1975.html.

Station 5: Acids, Bases, and pH p. 85, 86 in your textbook

http://www.brainpop.com/

http://es.brainpop.com/

http://www.quia.com/rd/1975.html






Station 5: Acids, Bases, and pH

Examine the diagram below and pages 85 and 96 in your textbook to answer the following

questions.

1. The pH scale is ___________.

2. The higher the number is, the more ___________ the solution.

3. The lower the number is, the more ____________ the solution.

4. A pH of _____________ is neutral.

5. A neutral solution has equal amounts of ________ and ________ ions.

6. An acidic solution has more ________ ions than _________ ions.

7. A basic solution has more ________ ions than _________ ions.

8. A __________ helps a solution resist changes in pH.

Word Bank: H+, OH-, buffer, 7, H+, acidic, OH-, basic, H+, 1 to 14, OH-



Station 4: Quia’s The pH scale

Using www.quia.com/rd/1975.html, put the list in order by entering the numbers 1 through

14 in the fields provided. Do not record your answers on the worksheet until you know thatthey are correct.

Vinegar

Tomatoes

Pure Water

Household Ammonia

Baking Soda

Coffee

Lemon Juice

Stomach Fluids

Rolaids, Tums Bleach

Lye

Blood

Milk

Borax





Station 3: Can Lake Life Remain Despite Acid Rain?

Question: Why does acid rain harm some lakes more than others?

Background: Acid rain is caused by chemical pollutants in the air. These chemical

pollutants are mainly sulfur oxides and nitrogen oxides formed when coal and otherfossil fuels are burned in factories and cars. When sulfur oxide and nitrogen oxidedissolve in water, they form sulfuric acid and nitric acid. Rainwater in unpollutedareas has a pH of 5.5. Rainwater with a pH of lower than 5.5 is considered acidrain.

When acid rain falls and collects in lake environments, it can change the pH of the

lake water. This impacts the plants and animals that live in the lake.

Activity: The Adirondack lakes located in the Adirondack Mountains of New York.People that use the lakes have noticed than some of the lakes have less plants andanimals compared to other lakes. Compare the following lakes: Brant Lake, Big

Moose Lake, and Blue Mountain Lake in Data Table 1 and answer the followingquestions.

Characteristic Brant Lake Big Moose Lake Blue Mountain Lake

Size 5.7 km2 5.2 km2 5.5 km2

Elevation 243 m 556 m 545 m

Water Color Clear Brown Clear

pH 7.6 5.5 7.2

Algae growth Moderate Low Low

Phosphorus

levels

Low Low Low

Nitrogen levels Low Moderate to high moderate

Questions:

1. What are four characteristics Big Moose Lake and Blue Mountain Lake

have in common?

2. What are four characteristics Brant Lake and Blue Mountain Lake have incommon?

3. Algae typically grows in high nitrogen levels. Although Big Moose Lake hasmoderate to high nitrogen levels, it has low algae growth. Make a hypothesis

to explain low algae growth in Big Moose Lake.



4. When water pH is low, the decomposition rates (breakdown of plant andanimal debris) slow down. Explain how the low pH of Big Moose Lake could

affect its appearance.

Organism pH 6.5 pH 6.0 pH 5.5 pH 5.0 pH 4.5 pH 4.0

TroutBass

Perch

Frogs

Salamanders

Clams

Crayfish

Snails

MayfliesSource: EPA, Acid Rain Program

5. Which animal is the most sensitive to acid rain?

6. Which animal is the least sensitive to acid rain?

7. Based on this information, which animals would you find in Brant Lake,but not in Big Moose Lake?



Station 2: Brainpop’s Acids and Bases video and quiz

Log into http://www.brainpop.com. Click on science and then on acids andbases. Watch the video and then answer the quiz questions.

*There is a Spanish version of the video – http://es.brainpop.com. Followthe same directions as above.

1. What are two characteristics of acids?

2. What are two examples of acids?

3. What type of ions do acids produce when they are dissolved in water?

4. What are two things that acids can do?

5. What does the pH in the pH scale stand for?

6. Solutions with a pH of 6 or lower are considered ___________.

7. What is an example of something that is pH neutral?

8. What type of ions do bases produce when they are dissolved in water?

9. What are two examples of bases?

10. What are two characteristics of bases?

When you are done watching the video, click on “Take a Pop Quiz.” Select

the review quiz option.







Station 1: The pH Scale

You must be wearing

goggles at all times at this

station!!!!!!!

Part I: Background Information

Uses pg. 85 and 86 in your textbook to answer the following questions.

1. What is the pH scale and what does it measure?

2. How does a substance become acidic or basic (HINT: think ions)?

Part II: Data Collection

Predict the pH value of the following substances. Then use the litmus paperindicators, determine the actual pH of each substance.

Substance Predicted pH

value

Actual pH value Acidic, Basic, or

Neutral?



Part III: Data Analysis1. What types of products had a high pH?

2. What types of products had a low pH?

3. In order, list the acidic substances (pH 1 to 6) from highest H+ ions to

lowest H+ ions.

4. In order, list the basic substances (pH 8 to 14) highest OH

-

ions to lowestOH- ions.

5. What substances were neutral and what makes the substances neutral(HINT: Think ions)?

6. Based on the known pH values for the substances that you test, predict if

the following substances are acidic, basic, or neutral.

Circle one for each substance:Stomach Acid acidic basic neutral

Saliva acidic basic neutralHuman blood acidic basic neutral

Acid rain acidic basic neutral

Sulfuric acid acidic basic neutralLysol (ammonia) acidic basic neutral

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