Question

1. a student mixes strawberry kool - aid and water. a ph meter is used to measure ph of 5.4. what kind of solution is strawberry kool - aid?
2. in the kool - aid mixture, what must there be more of, hydrogen ions or hydroxide ions?
3. a student adds an alka - seltzer to the kool - aid and stirs. the ph meter now reads 8.3. what was released by the alka - seltzer tablet to cause this change?
4. bromthymol blue is a chemical indicator that is blue in basic and neutral solutions, and turns greenish and then yellow as the solution becomes more and more acidic. fill in what color you think bromthymol blue would be in each of the situations in the chart.

chart:
situation | ph | bromthymol blue indicator color
water directly out of tap | ph = 7.2 |
ph after exhaled air is blown through a straw into water for 5 min. | ph = 5.1 |
ph after a snail has lived in water for three days | ph = 5.8 |
ph with 2ml of bleach added to the water | ph = 9.4 |
ph with instant coffee added to the water | ph = 5.0 |
ph after an aquatic plant is grown in water for three days in bright sunlight | ph = 7.7 |

a. what effect does carbon dioxide have on tap water?
b. is bleach an acid or a base?
c. is coffee an acid or a base?

Explanation:

Question 14 (Assuming the first question is about the type of solution with pH 5.4)

Step1: Recall pH scale

The pH scale ranges from 0 - 14. Solutions with \( \text{pH} < 7 \) are acidic, \( \text{pH} = 7 \) are neutral, and \( \text{pH} > 7 \) are basic.

Step2: Classify the solution

Given \( \text{pH} = 5.4 \), since \( 5.4 < 7 \), the solution is acidic.

Step1: Recall ion - pH relationship

In an aqueous solution, the concentration of hydrogen ions (\( \ce{H+} \)) and hydroxide ions (\( \ce{OH-} \)) determines pH. For acidic solutions (\( \text{pH} < 7 \)), \( [\ce{H+}]>[\ce{OH-}] \); for basic solutions (\( \text{pH} > 7 \)), \( [\ce{OH-}]>[\ce{H+}] \); and for neutral solutions (\( \text{pH} = 7 \)), \( [\ce{H+}]=[\ce{OH-}] \).

Step2: Determine ion concentration in Kool - Aid

Since the Kool - Aid solution has a pH of 5.4 (acidic), there must be more hydrogen ions (\( \ce{H+} \)) than hydroxide ions (\( \ce{OH-} \)).

Step1: Analyze pH change

The initial pH of Kool - Aid is 5.4 (acidic), and after adding the alka - seltzer, the pH becomes 8.3 (basic). So the alka - seltzer must be a basic substance.

Step2: Identify ions released by bases

Bases release hydroxide ions (\( \ce{OH-} \)) in solution. The hydroxide ions react with hydrogen ions (\( \ce{H+} \)) in the acidic Kool - Aid solution, increasing the pH (making it more basic).

Answer:

The strawberry Kool - Aid solution is acidic.

Question 15