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Acid rain and air pollution — Free MYP5 Chemistry Practice Questions
1QuestionpH scale and acidity measurementConcept Practice
2 marks~3 minCriterion A
Three strips of universal indicator paper were each dipped into a different substance.
- Strip A was dipped in lemon juice and turned red.
- Strip B was dipped in pure water and turned green.
- Strip C was dipped in soap solution and turned purple.
- Strip A was dipped in lemon juice and turned red.
- Strip B was dipped in pure water and turned green.
- Strip C was dipped in soap solution and turned purple.
a
Deduce the nature (acidic, neutral, or alkaline) of each substance, based on the colour changes observed. [1]
b
Acid rain has a pH of approximately 4. Explain why acid rain, despite being acidic, causes less damage to living organisms than the substance in Strip A would if consumed in large quantities. [1]
Solutions
2QuestionEffects on soil, water bodies, and buildingsAssessment Practice
2 marks~3 minCriterion D
Acid rain containing sulfuric acid reacts with limestone (calcium carbonate) in buildings, causing structural damage.
a
Complete and balance the chemical equation for this reaction:
Explain how the products cause damage to the limestone structure. [1]
Explain how the products cause damage to the limestone structure. [1]
b
Granite is sometimes proposed as a replacement for limestone in heritage building restoration. Explain why granite resists acid rain more effectively than limestone, and discuss whether replacing limestone with granite fully eliminates the risk of weathering damage. [1]
Solutions
3QuestionMethods to reduce acid rain (clean fuels, scrubbers)Assessment Practice
6 marks~9 minCriterion C
A wet scrubber removes from industrial flue gas using a slurry:
removal efficiency was measured at two pH levels across a range of inlet gas temperatures.
removal efficiency was measured at two pH levels across a range of inlet gas temperatures.
| Inlet gas temperature (°C) | 25 | 35 | 45 | 55 | 65 |
|---|---|---|---|---|---|
| removal at pH 5.0 (\%) | 92 | 88 | 82 | 75 | 68 |
| removal at pH 6.0 (\%) | 95 | 91 | 70 | 78 | 72 |
a
Describe the trend in removal efficiency as temperature increases at pH 5.0. [1]
b
Identify the anomalous data point at pH 6.0, stating the temperature at which it occurs and how it departs from the expected trend. [2]
c
Analyse why removal efficiency at pH 6.0 is generally higher than at pH 5.0, and explain why the anomaly at 45°C is more pronounced at pH 6.0 than at pH 5.0. [3]
Solutions
4QuestionChemical equations leading to acidic precipitationAssessment Practice
8 marks~12 minCriterion B
When nonmetal oxides dissolve in water, they form acidic solutions. The table below shows data for four oxides relevant to acid rain.
| Oxide | ||||
|---|---|---|---|---|
| pH of solution | 5.6 | 4.5 | 3.2 | 2.1 |
| Oxidation state of nonmetal | +4 | +4 | +4 | +6 |
a
Describe the trend in pH as the oxidation state of the nonmetal increases, using data from the table to support your answer. [2]
b
Deduce the pH of the solution formed when reacts with water, given that phosphorus has an oxidation state of +5 in this oxide. Use the trend from part (a) to support your reasoning. [2]
c
Justify why nonmetal oxides with higher oxidation states produce more acidic solutions, by explaining how the oxidation state affects O–H bond polarity in the oxyacid formed and how this determines the strength of the acid. [4]
Solutions
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