Chemical Reactions and Bonding — Free IB MYP4 Chemistry Questions

1QuestionSingle and Double Displacement ReactionsConcept Practice

4 marks~6 minCriterion A

In an industrial metal recovery process, zinc pellets are added to a copper(II) sulfate solution. A reaction occurs spontaneously at room temperature.

a

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

b

Deduce two observable changes that occur as the reaction proceeds, linking each observation to a specific chemical change taking place. [2]

Solutions

2QuestionThe Reactivity Series of MetalsConcept Practice

2 marks~3 minCriterion A

A piece of zinc metal is placed in a beaker containing copper(II) sulfate solution. Over time, a reddish-brown solid forms on the zinc surface and the solution changes colour.

a

Deduce the identity of the reddish-brown solid, and write the balanced chemical equation for this reaction. [1]

b

Explain, using the reactivity series, why zinc displaces copper from solution but copper would not displace zinc if the metals were swapped. [1]

Solutions

3QuestionBond strength, melting points and conductivityConcept Practice

2 marks~3 minCriterion A

The diagram shows sodium and chlorine atoms before and after forming sodium chloride,

NaCl

.

a

Describe the electron transfer that occurs when a sodium atom reacts with a chlorine atom to form ions. Include the correct ion symbols in your answer. [1]

b

Explain how the ions formed in part (a) produce a stable ionic compound. [1]

Solutions

4QuestionMass Changes in Closed and Open SystemsConcept Practice

2 marks~3 minCriterion A

A student adds 5.0 g of sodium carbonate (

Na_2CO_3

) to a sealed flask containing excess hydrochloric acid (

HCl

). The reaction is:

Na_2CO_3(s) + 2HCl(aq) \rightarrow 2NaCl(aq) + H_2O(l) + CO_2(g)

The student records the total mass of the sealed flask before and after the reaction and finds it unchanged.

a

State the law that explains why the total mass remains unchanged. [1]

b

Explain why the mass would decrease if the flask were left open during the same reaction. [1]

Solutions

5QuestionObserving Chemical Change Color Gas Temperature PrecipitateAssessment Practice

7 marks~11 minCriterion C

In an investigation, 10 mL of 0.5 M hydrochloric acid was added to separate samples of four metal carbonates at 25°C. Observations are recorded below.

Reaction 1 — Sodium carbonate: no colour change; many gas bubbles; temperature change +8°C; no precipitate
Reaction 2 — Calcium carbonate: no colour change; many gas bubbles; temperature change +5°C; white precipitate
Reaction 3 — Magnesium carbonate: no colour change; few gas bubbles; temperature change +2°C; no precipitate
Reaction 4 — Potassium carbonate: no colour change; many gas bubbles; temperature change +7°C; no precipitate

a

Identify which reaction shows an anomalous result. Justify your answer by referring to specific data from the table. [3]

b

Deduce one chemical and one physical factor that could explain the reduced reactivity observed in that reaction. [4]

Solutions

6QuestionPrecipitation and Gas Formation ReactionsAssessment Practice

8 marks~12 minCriterion D

A municipal wastewater facility receives industrial wastewater containing 200 mg/L of sulfate ions (

\text{SO}_4^{2-}

). Barium chloride (

\text{BaCl}_2

) is added to precipitate sulfate as barium sulfate (

\text{BaSO}_4

), which is then removed by filtration:

\text{BaCl}_2(aq) + \text{Na}_2\text{SO}_4(aq) \rightarrow \text{BaSO}_4(s) + 2\text{NaCl}(aq)

Barium ions (

\text{Ba}^{2+}

) are toxic to aquatic life above 1.0 mg/L.

K_{sp}(\text{BaSO}_4) = 1.1 \times 10^{-10}

.

Molar masses (g/mol): Ba = 137.3, Cl = 35.5, S = 32.1, O = 16.0.

a

Calculate the minimum mass of

\text{BaCl}_2

(in grams) needed to completely precipitate the sulfate ions from 1000 L of wastewater. [2]

b

Deduce the concentration of

\text{Ba}^{2+}

(in mg/L) remaining in the treated water after filtration, and state whether it exceeds the toxicity threshold. [2]

c

Evaluate the environmental trade-offs of using barium chloride precipitation for sulfate removal. In your answer: identify one environmental benefit of removing sulfate; identify one environmental risk introduced by barium chloride; and discuss two limitations of applying the

K_{sp}

calculation from part (b) to predict real-world treatment outcomes. [4]

Solutions

7QuestionObserving Chemical Change Color Gas Temperature PrecipitateAssessment Practice

6 marks~9 minCriterion B

A student investigates how the concentration of sodium carbonate (Na

_2

CO

_3

) solution affects the mass of calcium carbonate (CaCO

_3

) precipitate formed with excess calcium chloride (CaCl

_2

) solution. The reaction is:

\text{Na}_2\text{CO}_3(aq) + \text{CaCl}_2(aq) \rightarrow \text{CaCO}_3(s) + 2\text{NaCl}(aq)

The volume of Na

_2

CO

_3

is fixed at 50.0 mL; CaCl

_2

is 50.0 mL at 0.50 M throughout.

Concentration of Na

_2

CO

_3

(M): 0.10, 0.20, 0.30, 0.40, 0.50

Mass of CaCO

_3

precipitate (g): 0.50, 1.00, 1.50, 2.00, 2.50

a

Construct a graph of mass of CaCO

_3

precipitate (y-axis) against concentration of Na

_2

CO

_3

(x-axis) and interpret the pattern shown. [2]

b

Deduce the mathematical relationship between concentration of Na

_2

CO

_3

and mass of CaCO

_3

precipitate, showing your working. [2]

c

The student claims the relationship established in (b) can reliably predict the mass of precipitate at any Na

_2

CO

_3

concentration between 0.10 M and 0.50 M. Evaluate this claim for a concentration of 0.35 M, identifying one assumption that could limit the reliability of the prediction. [2]

Solutions

8QuestionThe Reactivity Series of MetalsAssessment Practice

8 marks~12 minCriterion C

A student investigates displacement reactions by placing five metals into aqueous nitrate solutions of the same metals. A tick (✓) indicates the metal displaced the other from solution; a cross (✗) indicates no reaction; a dash (—) indicates the metal was not tested against its own solution.

Metal added —

Mg(NO_3)_2

—

Zn(NO_3)_2

—

Fe(NO_3)_2

—

Cu(NO_3)_2

—

AgNO_3

Mg:	✓ ✓ ✓ ✓
Zn: ✗	✓ ✓ ✓
Fe: ✗ ✗	✓ ✓
Cu: ✗ ✗ ✗	✓

Ag: ✗ ✗ ✗ ✗ —

a

Deduce the order of decreasing reactivity of the five metals and explain the pattern in the data that allows this order to be determined. [2]

b

Deduce whether a reaction occurs when zinc is placed into iron(II) nitrate solution,

Fe(NO_3)_2(aq)

. Write the balanced chemical equation with state symbols if a reaction occurs, or state "no reaction." [2]

c

A student claims: "Any metal will displace any other metal from its nitrate solution, provided enough time is given." Evaluate this claim by referring to the reactivity order from (a) and explaining the electron transfer process that determines whether displacement occurs. [4]

Solutions

9QuestionCorrosion and Methods of preventionAssessment Practice

3 marks~5 minCriterion D

An iron nail is partially submerged in water inside a test tube open to the air. Rust forms most heavily at the waterline — the boundary between the liquid water and the air above it.

a

Identify the two reactants required for iron to rust. [1]

b

Explain why rust forms most heavily at the waterline rather than on the fully submerged section of the nail. [1]

c

A student proposes coating the nail in a thin layer of zinc to prevent rusting. Evaluate whether this method would protect the nail even if the zinc coating is scratched and the iron beneath is exposed. [1]

Solutions

10QuestionRedox ReactionsAssessment Practice

6 marks~9 minCriterion B

A student investigates how the concentration of hydrochloric acid (HCl) affects its reaction rate with magnesium ribbon at

25^\circ\text{C}

. The time for the ribbon to completely dissolve is recorded.

Concentration of HCl ( $\text{mol dm}^{-3}$ )	0.5	1.0	1.5	2.0	2.5
Time (s)	120	60	40	30	24

The reaction is:

\text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2

a

Construct a graph of rate of reaction (

s^{-1}

), where rate

= \dfrac{1}{\text{time}}

, against concentration of HCl (

\text{mol dm}^{-3}

). Describe the shape of the graph. [2]

b

Interpret the graph to deduce the mathematical relationship between concentration of HCl and rate of reaction, using specific values from the data to support your answer. [2]

c

A student claims that at

3.0\ \text{mol dm}^{-3}

, the reaction time will be 20 s. Evaluate this prediction, identifying one assumption the student must make and one experimental factor that could cause the actual result to differ. [2]

Solutions

11QuestionStructure and Properties of Metallic BondsAssessment Practice

4 marks~6 minCriterion B

The table below shows the melting points of Group 1 metals.

Element	Li	Na	K	Rb	Cs
Melting point (°C)	180	98	64	39	28

a

Describe the trend in melting points down Group 1. [1]

b

Deduce the melting point of francium (Fr), the next element in Group 1, and justify your prediction using metallic bonding theory. [3]

Solutions

12QuestionStructure and Properties of Metallic BondsAssessment Practice

8 marks~12 minCriterion D

Stainless steel, an alloy of iron, chromium, and nickel, is widely used for surgical instruments. Its melting point is approximately

1400\ ^\circ\text{C}

, and chromium forms a surface oxide layer (

\text{Cr}_2\text{O}_3

) that resists corrosion. Recycling stainless steel is energy-intensive and requires separation of its alloy components to meet medical-grade purity standards.

a

Explain how the metallic bonding structure of stainless steel accounts for both its high strength and its corrosion resistance. [2]

b

Discuss the societal benefits of stainless steel surgical instruments for the healthcare sector, addressing both health and economic dimensions. [2]

c

Analyse the environmental costs of recycling stainless steel, considering its high melting point and the challenges of separating its alloy components. [2]

d

Evaluate whether the societal benefits of stainless steel surgical instruments outweigh the environmental costs, and justify one strategy to reduce the environmental impact of its production or recycling. [2]

Solutions

13QuestionFormation and Diagrams of Covalent BondsAssessment Practice

6 marks~9 minCriterion C

The table below shows electronegativity (EN) values on the Pauling scale and bond dissociation energies (BDE) at 298 K for bonds between hydrogen and selected second-period non-metals.

Element	H	C	N	O
EN	2.20	2.55	3.04	3.44

Bond	H–H	C–H	N–H	O–H
BDE (kJ mol $^{-1}$ )	436	413	391	463

a

Calculate the electronegativity difference,

|\Delta \text{EN}|

, for each of the four bonds. [1]

b

Deduce the order of the four bonds from least polar to most polar, and explain how the electronegativity differences support this order. [2]

c

Analyse the relationship between bond polarity and bond dissociation energy. Identify one bond whose BDE does not follow the trend expected from polarity alone, and justify your answer by referring to atomic properties. [3]

Solutions

14QuestionIdentifying Reactants and ProductsAssessment Practice

3 marks~5 minCriterion C

A 0.50 g piece of magnesium ribbon reacts with excess hydrochloric acid. The graph shows the mass of magnesium remaining plotted against time.

a

Describe the shape of the graph. [1]

b

Explain why the gradient of the graph decreases as the reaction proceeds. [1]

c

A student claims that the graph would reach zero mass if enough time were allowed. Evaluate this claim using your knowledge of limiting and excess reactants. [1]

Solutions

15QuestionWord Equations and Symbol EquationsAssessment Practice

4 marks~6 minCriterion A

The diagrams below show two models of chemical substances.

Diagram 1: A repeating cubic lattice of alternating spheres labelled

Na^+

and

Cl^-

.

Diagram 2: Discrete molecules, each with one central sphere labelled O (

\delta^-

) bonded to two smaller spheres labelled H (

\delta^+

).

a

Identify the type of compound shown in each diagram. [1]

b

Explain the bonding and structure visible in Diagram 1 and Diagram 2. [2]

c

The partial charges (

\delta^-

and

\delta^+

) are shown in Diagram 2 but not in Diagram 1. Explain why partial charges are used to describe the bonding in Diagram 2 and why they would be inappropriate for Diagram 1. [1]

Solutions

16QuestionState Symbols in Chemical ReactionsAssessment Practice

8 marks~12 minCriterion B

Consider the following balanced equations for the reactions of elements with oxygen:

2\text{Mg(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{MgO(s)}

2\text{Ca(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{CaO(s)}

4\text{Na(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Na}_2\text{O(s)}

\text{C(s)} + \text{O}_2\text{(g)} \rightarrow \text{CO}_2\text{(g)}

a

Identify the pattern in the state symbols of the products, linking each product's state to the position of the reacting element in the periodic table. [2]

b

Deduce the state symbol of barium oxide (BaO), the product formed when barium reacts with oxygen. Justify your answer using the pattern identified in (a) and barium's position in the periodic table. [2]

c

Discuss how the bonding and structure of BaO and CO2 differ, and explain how these differences account for the contrast in their physical states at room temperature. [4]

Solutions

17QuestionIdentifying Reactants and ProductsAssessment Practice

4 marks~6 minCriterion D

A student investigates a gas heater that burns propane (

C_3H_8

). The balanced equation for complete combustion is:

C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O

The student's model assumes all gas heaters undergo only complete combustion. However, if the oxygen supply is limited, incomplete combustion occurs, producing toxic carbon monoxide (

CO

) instead of

CO_2

.

a

Identify one environmental impact of releasing large amounts of

CO_2

from millions of household gas heaters. [1]

b

Explain how conditions inside a poorly ventilated room could lead to incomplete combustion and the production of

CO

. [1]

c

Evaluate the student's model, discussing why assuming only complete combustion underestimates the health risks associated with gas heaters. [2]

Solutions

18QuestionBalancing Simple Chemical EquationsAssessment Practice

6 marks~9 minCriterion B

When a hydrocarbon burns completely in excess oxygen, the only products are carbon dioxide (

CO_2

) and water (

H_2O

). The table below shows combustion data for four alkanes.

Hydrocarbon	$CH_4$	$C_2H_6$	$C_3H_8$	$C_4H_{10}$
$CO_2$ molecules produced	1	2	3	4
$H_2O$ molecules produced	2	3	4	5

a

Deduce the relationship between the molecular formula of a hydrocarbon and the number of

CO_2

and

H_2O

molecules produced during complete combustion. [2]

b

Predict the number of

CO_2

and

H_2O

molecules produced when one molecule of pentane (

C_5H_{12}

) burns completely in excess oxygen, and explain your reasoning. [2]

c

A student claims: "The pattern in the table is just a coincidence — it does not have to follow the law of conservation of mass." Justify whether this claim is correct or incorrect, using the balanced equation for the complete combustion of pentane as evidence. [2]

Solutions

19QuestionBalancing Simple Chemical EquationsAssessment Practice

2 marks~3 minCriterion D

Natural gas power stations burn methane according to:

CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O

a

Identify one environmental impact of methane combustion that can be deduced directly from this equation. [1]

b

Evaluate one limitation of using this equation to model the environmental impact of real-world natural gas combustion. [1]

Solutions

20QuestionBalancing Complex Reactions with Polyatomic IonsAssessment Practice

4 marks~6 minCriterion C

Aluminium hydroxide reacts with nitric acid according to the unbalanced equation:

\text{Al(OH)}_3(aq) + \text{HNO}_3(aq) \rightarrow \text{Al(NO}_3)_3(aq) + \text{H}_2\text{O}(l)

a

Construct the balanced equation, treating the nitrate ion (

\text{NO}_3^-

) as a single unit. [2]

b

Justify why the coefficient of water in the balanced equation must be 3, using the conservation of mass. Your answer must account for both hydrogen and oxygen atoms. [2]

Solutions

Chemical Reactions and Bonding — Free MYP4 Chemistry Practice Questions