Name: Date:

Science 10: 5-1B Properties of Acids and Bases

Purpose: To investigate to acid-base properties of four solutions.

Materials: 4x6 Spot Plate Masking Tape Solutions A, B, C, D

4 pieces of Mg ribbon 4 red litmus pieces 4 blue litmus pieces

Bromothymol Blue Solution Indigo Carmine Solution Methyl Orange Solution

Procedure:

1. Use masking tape to label each row on the spot plate A, B, C, D.

2. Add a few drops of each solution to their appropriate row (ex. Solution A is placed in Row A).

3. Place a piece of Mg ribbon in the first well of each row (see diagram).

4. Place red litmus in the second well and blue litmus in the third well.

5. Place five drops of bromothymol blue in the fourth well, five drops of indigo carmine to the fifth well and five drops of methyl orange to the sixth well.

6. Record the results in your data table. State the colour or other observations.

7. Show your teacher your spot plate before you clean up!

8. Clean your plate by washing the chemicals down the drain.

Observations

Solutions / Indicators
Mg Ribbon / Red Litmus / Blue Litmus / Bromothymol Blue / Indigo Carmine / Methyl Orange
A
B
C
D

Analyze

1. List the solutions in order from most acidic to least acidic.

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2. Which solution do you think was neutral? Explain how you know.

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3. You used two bases. Explain how you know which solution was more alkaline.

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4. How can Mg ribbon metal be used to distinguish between an acid and a base?

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Conclude and Apply

1. a) What colour would each of the five indicators be in a solution that is pH 3?

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b) What colour would each of the five indicators be in a solution that is pH 10?

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2. Imagine you are sked to put together a test kit to determine whether water taken from a factory waste drain is acidic, basic or neutral. What three tests would your kit contain?

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3. What colour would a sample of Rocella tinctoria lichen turn is ground up and placed in vinegar?

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4. What colout would seawater turn if it had bromothymol blue added to it?

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5. Consider the colour-coded map of the world’s oceans.

a) Which regions of the world’s oceans appear to be most affected by the drop in pH level?

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b) Which regions are the least affected?

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Science 10: 5-1B LabPage 3