Acids Bases and Salts — Free IB MYP4 Chemistry Questions

1QuestionUsing Acid + Base Acid + Metal Acid + Carbonate ReactionsConcept Practice

2 marks~3 minCriterion A

A titration is performed to prepare a pure sample of sodium chloride. A burette filled with hydrochloric acid (

\text{HCl}

) is clamped above a conical flask containing sodium hydroxide solution (

\text{NaOH}

) and a few drops of phenolphthalein indicator. The conical flask rests on a white tile. Equipment label X indicates the burette.

a

Identify the colour change of phenolphthalein that signals the endpoint of this titration. [1]

b

Explain why the white tile is placed beneath the conical flask during the titration. [1]

Solutions

2QuestionpH Control in Agriculture and Swimming PoolsConcept Practice

2 marks~3 minCriterion A

A diagram shows three pH-testing methods: a pH meter probe, a strip of universal indicator paper, and a piece of red litmus paper.

An agricultural scientist needs to determine the exact pH of a soil sample to decide whether lime should be added before planting.

a

Identify the apparatus from the diagram that provides an accurate numerical pH value. [1]

b

Explain why the other two methods are unsuitable for this purpose. [1]

Solutions

3QuestionConductivity of Acidic and Basic SolutionsConcept Practice

3 marks~5 minCriterion A

The table below shows the conductivity of hydrochloric acid (

HCl

) solutions at four concentrations.

Concentration (M)	0.1	0.5	1.0	2.0
Conductivity (S/m)	0.42	1.98	3.85	7.50

a

Identify the trend shown in the data. [1]

b

Explain why increasing the concentration of

HCl

increases the number of mobile ions in solution. [1]

c

Analyse how the relationship between mobile ion concentration and conductivity accounts for the pattern observed in the data. [1]

Solutions

4QuestionUsing Litmus Universal and Natural IndicatorsConcept Practice

2 marks~3 minCriterion A

A student investigates natural indicators by adding red cabbage juice to three test tubes.

Test tube 1: lemon juice → turns red
Test tube 2: soap solution → turns green
Test tube 3: pure water → turns purple

a

Identify which test tube contains an acid. [1]

b

Explain how the colour change in that test tube confirms the solution is acidic. [1]

Solutions

5QuestionWord and Symbol Equations for NeutralizationConcept Practice

3 marks~5 minCriterion B

Four neutralization reactions and their salt products are shown below.

Acid: hydrochloric acid ( $\text{HCl}$ )	Base: sodium hydroxide ( $\text{NaOH}$ )	Salt: sodium chloride
Acid: sulfuric acid ( $\text{H}_2\text{SO}_4$ )	Base: potassium hydroxide ( $\text{KOH}$ )	Salt: potassium sulfate
Acid: nitric acid ( $\text{HNO}_3$ )	Base: calcium hydroxide ( $\text{Ca(OH)}_2$ )	Salt: calcium nitrate
Acid: phosphoric acid ( $\text{H}_3\text{PO}_4$ )	Base: sodium hydroxide ( $\text{NaOH}$ )	Salt: sodium phosphate

a

Identify the pattern used to name the salts produced in neutralization reactions. [1]

b

Deduce the name of the salt formed when hydrobromic acid (

\text{HBr}

) reacts with magnesium hydroxide (

\text{Mg(OH)}_2

). [1]

c

Construct the word equation for the neutralization reaction between hydrobromic acid and magnesium hydroxide. [1]

Solutions

6QuestionDefinition and Real-Life Examples of NeutralizationConcept Practice

2 marks~3 minCriterion A

An antacid tablet containing calcium carbonate (

CaCO_3

) is added to a beaker of stomach acid (hydrochloric acid,

HCl

). The tablet dissolves, releasing bubbles of carbon dioxide gas (

CO_2

).

a

Identify the base in this neutralization reaction. [1]

b

Identify the salt produced in this neutralization reaction. [1]

Solutions

7QuestionUsing Acid + Base Acid + Metal Acid + Carbonate ReactionsAssessment Practice

3 marks~5 minCriterion B

When metal carbonates react with dilute hydrochloric acid, carbon dioxide gas is produced, observed as effervescence. The results for four carbonates are summarised below.

Carbonate	$Na_2CO_3$	$CaCO_3$	$CuCO_3$	$MgCO_3$
Reactivity of metal	Very high	High	Low	High
Effervescence rate	Very fast	Fast	Slow	Fast

a

State the general relationship between the reactivity of the metal in the carbonate and the observed rate of effervescence. [1]

b

Deduce which two carbonates in the table would produce the most similar rate of effervescence, and justify your answer using the data provided. [1]

c

Explain, in terms of carbon dioxide production, why the reactivity of the metal in the carbonate affects the rate of effervescence observed. [1]

Solutions

8QuestionFiltering Crystallizing and Drying a SaltAssessment Practice

6 marks~9 minCriterion D

A school chemistry class reacts copper(II) oxide with sulfuric acid to produce copper(II) sulfate crystals. After filtering and crystallising,

2 \, \text{dm}^3

of filtrate remains, containing dissolved copper(II) sulfate (

\text{CuSO}_4

,

M_r = 159.6 \, \text{g/mol}

) at

0.50 \, \text{mol dm}^{-3}

.

a

Calculate the mass of

\text{CuSO}_4

present in the filtrate. [2]

b

Explain the environmental risks of pouring this filtrate into a river, referring to the toxicity of copper ions to aquatic organisms and the process of bioaccumulation. [2]

c

Analyse two possible methods for disposing of the filtrate responsibly in a school laboratory, and justify which method is more appropriate. [2]

Solutions

9QuestionPreparing Soluble Salts Using Different MethodsAssessment Practice

6 marks~9 minCriterion C

A student hypothesises that using excess insoluble base always produces the highest yield of soluble salt. Three trials prepared copper(II) sulfate crystals by adding copper(II) oxide powder to 50 cm³ of 1.0 mol/dm³ sulfuric acid. The mixture was heated, stirred, filtered, and the filtrate evaporated to obtain crystals.

Trial A: 8.0 g CuO added — crystal mass: 7.6 g, pH of filtrate: 7
Trial B: 12.0 g CuO added — crystal mass: 7.8 g, pH of filtrate: 7
Trial C: 16.0 g CuO added — crystal mass: 7.5 g, pH of filtrate: 7

The theoretical maximum yield of copper(II) sulfate from 50 cm³ of 1.0 mol/dm³

\text{H}_2\text{SO}_4

is 7.98 g.

a

Calculate the percentage yield for Trial B using:

\text{Percentage yield} = \left(\frac{\text{Actual yield}}{\text{Theoretical yield}}\right) \times 100

[2]

b

Using all three trials, evaluate the student's hypothesis. In your answer, identify which trial(s) support and which refute the hypothesis, and explain the role of excess base in determining the final crystal yield. [4]

Solutions

10QuestionpH Control in Agriculture and Swimming PoolsAssessment Practice

2 marks~3 minCriterion B

A farmer tests the effect of adding lime (calcium oxide) to three soil types. The pH of each soil is measured after adding 0 g, 5 g, and 10 g of lime.

Lime added (g): 0	5	10
Sandy soil pH: 5.0	6.0	7.0
Clay soil pH: 5.5	6.5	7.5
Loamy soil pH: 6.0	7.0	8.0

Peat soil has a natural pH of 4.5 with 0 g of lime added.

a

Deduce the relationship between the mass of lime added and the pH change observed across all three soil types. [1]

b

A farmer needs peat soil to reach a pH of at least 6.5 for optimal crop growth. Evaluate whether adding 10 g of lime is sufficient, and justify your answer using the pattern from the data. [1]

Solutions

11QuestionSafety and Storage of Corrosive SubstancesAssessment Practice

2 marks~3 minCriterion D

A laboratory technician finds an unlabelled bottle containing

\text{H}_2\text{SO}_4\text{(aq)}

on a bench next to an eyewash station. The bottle is missing its GHS hazard symbol.

a

Identify the GHS hazard symbol that must appear on the bottle of

\text{H}_2\text{SO}_4\text{(aq)}

, and state what the symbol indicates about the substance. [1]

b

Explain why an eyewash station, rather than a standard tap, is the appropriate first-aid response if

\text{H}_2\text{SO}_4\text{(aq)}

contacts a student's eyes. [1]

Solutions

12QuestionBases in Everyday Products Soap Toothpaste Drain CleanersAssessment Practice

5 marks~8 minCriterion C

Four household products are tested: soap, toothpaste, drain cleaner, and an unknown substance labelled X. The table below shows the pH, reaction with 1.0 M HCl (droplet test), reaction with 1.0 M NaOH (droplet test), and conductivity of a 1% solution at 25°C.

Product: Soap, Toothpaste, Drain cleaner, X

pH: 9, 8, 13, 11

Reaction with HCl: Fizzes mildly, Fizzes mildly, Vigorous fizzing, Fizzes moderately

Reaction with NaOH: No visible change, No visible change, No visible change, No visible change

Conductivity: Low, Low, High, Moderate

a

[2 marks] Deduce which of the four products is the strongest base. Explain your reasoning using the pH data and the reaction with HCl.

b

[3 marks] Deduce the identity of substance X. Justify your deduction by comparing all three properties (pH, reaction with HCl, and conductivity) to the known products.

Solutions

13QuestionLaboratory Safety When Handling Acids and BasesAssessment Practice

2 marks~3 minCriterion B

During a chemistry practical, four acid/base accidents were investigated.

Accident 1 — Hazard: acid splash to eyes | Cause: beaker tipped on bench | Missing precaution: goggles

Accident 2 — Hazard: base spill spreading across bench | Cause: bottle knocked off shelf | Missing precaution: spill tray

Accident 3 — Hazard: hand cut from broken glass | Cause: beaker dropped while carrying | Missing precaution: gloves

Accident 4 — Hazard: fume inhalation | Cause: acid–base reaction performed in open air | Missing precaution: fume hood

Accident 5 — Hazard: acid burn on hand | Cause: pouring concentrated acid into a beaker

Analyse the relationship between the missing safety precaution and the type of hazard in Accidents 1–4, then justify which single precaution would most likely prevent the injury in Accident 5. [2]

Solutions

14QuestionConductivity of Acidic and Basic SolutionsAssessment Practice

6 marks~9 minCriterion C

A student measures the conductivity of hydrochloric acid (

\text{HCl}

) and acetic acid (

\text{CH}_3\text{COOH}

) at three concentrations.

Concentration (mol/L): 0.1, 0.5, 1.0

Conductivity of

\text{HCl}

(mS/cm): 4.3, 21.5, 43.0

Conductivity of

\text{CH}_3\text{COOH}

(mS/cm): 0.5, 1.1, 1.6

a

Describe the relationship between concentration and conductivity for each acid. [2]

b

Justify why the conductivity of

\text{HCl}

is much greater than that of

\text{CH}_3\text{COOH}

at the same concentration, using the concept of dissociation. [2]

c

The student tests 0.5 mol/L sulfuric acid (

\text{H}_2\text{SO}_4

). Analyse whether its conductivity would be greater than, equal to, or less than that of 0.5 mol/L

\text{HCl}

, and explain why it would not be exactly double. [2]

Solutions

15QuestionCommon Examples and Uses of Acids and BasesAssessment Practice

8 marks~12 minCriterion D

Acid rain has lowered the pH of many Scandinavian lakes to below 5, causing widespread loss of fish populations. Environmental agencies have responded by aerially distributing powdered limestone (

CaCO_3

) across affected lakes.

a

Write the balanced chemical equation for the reaction between limestone and the acid present in lake water, represented as

H^+

ions. State the role of

CaCO_3

in this reaction. [2]

b

Explain how this neutralization treatment affects the aquatic ecosystem of an acidified lake. [2]

c

Evaluate the societal and environmental trade-offs of using limestone liming as a long-term strategy to manage acid rain damage. [4]

Solutions

16QuestionEveryday Substances and Their pH ValuesAssessment Practice

3 marks~5 minCriterion B

The pH values of six household substances are listed below.

Substance	pH value
Lemon juice	2.5
Vinegar	3.0
Milk	6.5
Pure water	7.0
Baking soda solution	8.5
Soap solution	10.0

a

Identify the neutral substance from the list. [1]

b

Classify each remaining substance as acidic or basic, using its pH value as evidence. [1]

c

Analyse how the data shows a trend in acidity and alkalinity across the six substances, and explain what this trend reveals about the relationship between pH and the strength of acidity or alkalinity. [1]

Solutions

17QuestionUnderstanding the pH Scale 0 to 14Assessment Practice

5 marks~8 minCriterion C

A student hypothesises that "adding any acid to an alkali immediately produces a neutral solution at pH 7." To test this, they add

HCl

solution (0.1 mol dm

^{-3}

) in 1 cm

^3

increments to 25 cm

^3

of

NaOH

solution (0.1 mol dm

^{-3}

), recording pH after each addition.

Volume of $HCl$ added (cm $^3$ )	0	1	2	3	4	5
pH	13	12	11	10	8	2

a

State the chemical equation for the reaction occurring during this experiment. [1]

b

Analyse the pH data to describe the trend observed as

HCl

is added to the

NaOH

solution. [2]

c

Evaluate whether the experimental evidence supports or refutes the student's hypothesis, justifying your answer with reference to the stoichiometry of the reaction. [2]

Solutions

18QuestionEveryday Substances and Their pH ValuesAssessment Practice

6 marks~9 minCriterion D

Rainwater pH was measured over one month at four locations near a coal-fired power plant. Average pH values are recorded below.

Location A (2 km upwind): 5.6
Location B (2 km downwind): 4.2
Location C (5 km downwind): 4.8
Location D (10 km downwind): 5.3

Pure rainwater has a natural pH of approximately 5.6 due to dissolved

CO_2

.

a

Describe the trend in pH with increasing distance downwind from the power plant. [1]

b

Explain how

SO_2

emissions from the power plant cause the pH values at locations B and C to be lower than at location A. [2]

c

A student measures the pH of a rainwater sample from location B using universal indicator paper and records pH 4.0. Analyse the reliability of this measurement, and justify whether it is sufficient for use in an environmental monitoring report. [3]

Solutions

19QuestionWord and Symbol Equations for NeutralizationAssessment Practice

5 marks~8 minCriterion C

A student mixes hydrochloric acid (

HCl

) with sodium hydroxide (

NaOH

) solution in a beaker. The mixture contains freely moving

H^+

,

Cl^-

,

Na^+

, and

OH^-

ions before the reaction occurs.

a

Construct the balanced word equation for the reaction between hydrochloric acid and sodium hydroxide. [1]

b

Construct the balanced symbol equation for this reaction, including state symbols. [2]

c

The student claims that the ionic equation

H^+(aq) + OH^-(aq) \rightarrow H_2O(l)

represents every neutralization reaction between a strong acid and a strong alkali, not just this one. Evaluate this claim. [2]

Solutions

20QuestionpH Changes During NeutralizationAssessment Practice

2 marks~3 minCriterion D

In many regions, agricultural soils become acidic due to rainfall and fertiliser use, reducing crop yields. A farmer tests the soil and finds a pH of 4.5. She applies calcium hydroxide,

Ca(OH)_2

, to raise the soil pH toward the optimal range of 6.0–7.0 for most crops.

a

Explain how applying

Ca(OH)_2

to acidic soil raises its pH, referring to the neutralization reaction that occurs. [1]

b

Identify one environmental risk of over-applying

Ca(OH)_2

to agricultural soil, and explain the chemical or ecological mechanism by which this risk arises. [1]

Solutions

Acids Bases and Salts — Free MYP4 Chemistry Practice Questions