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Constructed Response . Topic 8: Acids, bases and salt
Set A: Acid-base indicators, data interpretation, properties of acids and bases, pH
Base your answers to question 1 and 2 on the information below.
Three bottles of liquids labeled 1,2, and 3 were found in a storeroom.
One of the liquids is known to be drain cleaner. Drain cleaners contain
o
KOH or NaOH. The pH of each liquid at 25 C was determined with a
pH meter. The table below shows the test results.
pH Test Results
Bottle pH of liquid
1 3.8
2 7.0
Teacher Preview Copy
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3 12.8
1. Explain, in terms of pH values, why thymol blue 1.
is not a suitable indicator to distinguish between
the contents of bottle 1 and 2.
2. Explain how the pH results in this table enable 2.
a student to correctly concluded that bottle 3
contain the drain cleaner.
Set B: Relationship between ph and H+ concentration, indicator.
Base your answers to questions 3 through 5 on the information below.
A truck carrying concentrated nitric acid overturns and spills its contents.
The acid drains into a nearby pond. The pH of the pond water was 8.0 before
the spill. After the spill, the pond water is 1,000 times more acidic.
3. What is the new pH of the pond water after the spill? 3.
4. What color would bromthymol blue be at this new pH? 4.
5. Name an ion in the pond water that has increased in 5.
concentration due to the spill.
Set C: Indicator, titration calculation
Base your answer to the following questions on the information below.
A student titrates 60.0 mL of HNO3(aq) with 0.30 M NaOH(aq) . Phenolphthalein is
used as the indicator. After adding 42.2 mL of NaOH(aq), a color change remains
for 25 seconds, and the student stops the titration.
6. What color change does phenolphthalein 6.
undergo during this titration.
7. What is concentration of the HNO3 that was titrated? 7.
Copyright©2010 E3 Scholastic Publishing. All Rights Reserved. SurvivingChem.com 391
Set A: Acid-base indicators, data interpretation, properties of acids and bases, pH
Base your answers to question 1 and 2 on the information below.
Three bottles of liquids labeled 1,2, and 3 were found in a storeroom.
One of the liquids is known to be drain cleaner. Drain cleaners contain
o
KOH or NaOH. The pH of each liquid at 25 C was determined with a
pH meter. The table below shows the test results.
pH Test Results
Bottle pH of liquid
1 3.8
2 7.0
Teacher Preview Copy
Teacher Preview Copy
3 12.8
1. Explain, in terms of pH values, why thymol blue 1.
is not a suitable indicator to distinguish between
the contents of bottle 1 and 2.
2. Explain how the pH results in this table enable 2.
a student to correctly concluded that bottle 3
contain the drain cleaner.
Set B: Relationship between ph and H+ concentration, indicator.
Base your answers to questions 3 through 5 on the information below.
A truck carrying concentrated nitric acid overturns and spills its contents.
The acid drains into a nearby pond. The pH of the pond water was 8.0 before
the spill. After the spill, the pond water is 1,000 times more acidic.
3. What is the new pH of the pond water after the spill? 3.
4. What color would bromthymol blue be at this new pH? 4.
5. Name an ion in the pond water that has increased in 5.
concentration due to the spill.
Set C: Indicator, titration calculation
Base your answer to the following questions on the information below.
A student titrates 60.0 mL of HNO3(aq) with 0.30 M NaOH(aq) . Phenolphthalein is
used as the indicator. After adding 42.2 mL of NaOH(aq), a color change remains
for 25 seconds, and the student stops the titration.
6. What color change does phenolphthalein 6.
undergo during this titration.
7. What is concentration of the HNO3 that was titrated? 7.
Copyright©2010 E3 Scholastic Publishing. All Rights Reserved. SurvivingChem.com 391
