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Chemical Reactions and Bonding

Chemical Reactions and Bonding — Free MYP5 Chemistry Practice Questions

1QuestionCombustion Reactions Complete and IncompleteConcept Practice
2 marks~3 minCriterion A
A Bunsen burner can produce two distinct flames depending on the position of the air hole. In Diagram A, the air hole is open and the flame is blue. In Diagram B, the air hole is closed and the flame is yellow.
a
Identify which diagram (A or B) shows complete combustion, and state the colour of the flame produced. [1]
b
Explain why closing the air hole causes the flame to change colour. [1]
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2QuestionCorrosion and Methods of preventionConcept Practice
2 marks~3 minCriterion A
Steel structural frameworks in modern buildings are often galvanised to extend their service life.
a
Identify one architectural application of galvanised steel and explain how the zinc coating protects the underlying steel from corrosion. [1]
b
Describe one limitation of galvanising that an architect or engineer must consider when selecting it as a corrosion-prevention method. [1]
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3QuestionBond strength, melting points and conductivityConcept Practice
2 marks~3 minCriterion A
The diagram below shows the three-dimensional lattice structure of sodium chloride (NaCl), with alternating Na+\text{Na}^+ and Cl−\text{Cl}^- ions held in a regular arrangement.
a
Identify the type of bonding present in sodium chloride. [1]
b
The melting point of NaCl is 801 °C, while that of iodine (I₂) is 114 °C. Using your knowledge of structure and bonding, deduce why NaCl has a significantly higher melting point than iodine. [1]
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4QuestionIdentifying Reactants and ProductsConcept Practice
4 marks~6 minCriterion A
The diagram below shows a chemical reaction between hydrogen and oxygen.
a
Identify the reactants and the product in this reaction. [1]
b
Deduce the balanced chemical equation for this reaction, using the molecular counts shown in the diagram. [1]
c
Analyse how the arrangement of atoms changes during this reaction, and explain what this tells you about whether mass is conserved. [2]
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5QuestionBalancing Complex Reactions with Polyatomic IonsConcept Practice
2 marks~3 minCriterion A
Ammonium sulfate, (NH4)2SO4(NH_4)_2SO_4, is used as a nitrogen-rich fertiliser. It dissociates in water to release two types of polyatomic ion.
a
State the name and chemical formula of each polyatomic ion present in (NH4)2SO4(NH_4)_2SO_4. [1]
b
Deduce the charge on each ion and explain how the charges confirm that ammonium sulfate is electrically neutral. [1]
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6QuestionSingle and Double Displacement ReactionsAssessment Practice
5 marks~8 minCriterion C
The graph below shows the volume of hydrogen gas produced over time when equal masses of zinc and magnesium are each reacted with excess hydrochloric acid. Magnesium reaches 50 cm³ of hydrogen gas in 40 s; zinc reaches the same volume in 120 s. Both curves level off at 50 cm³.
a
State which metal reacts faster and give one piece of quantitative evidence from the graph to support your answer. [2]
b
Explain how the position of each metal in the reactivity series accounts for the difference in reaction rate observed in the graph. [2]
c
A student claims that because both metals produce the same final volume of hydrogen gas, they must be equally reactive. Evaluate this claim. [1]
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7QuestionPrecipitation and Gas Formation ReactionsAssessment Practice
6 marks~9 minCriterion B
A student mixes various volumes of 0.10 M silver nitrate (AgNO3AgNO_3) solution with 0.10 M sodium chloride (NaClNaCl) solution. After filtering and drying, the mass of precipitate is recorded.

Volume of AgNO3AgNO_3 (cm³): 10.0, 20.0, 30.0, 40.0, 50.0

Volume of NaClNaCl (cm³): 50.0, 40.0, 30.0, 20.0, 10.0

Mass of precipitate (g): 0.72, 1.43, 2.15, 1.43, 0.72

Solubility rules: all nitrates are soluble; chlorides of Ag+Ag^+, Pb2+Pb^{2+}, and Hg22+Hg_2^{2+} are insoluble; all sodium salts are soluble.
a
Using the solubility rules, deduce the identity of the precipitate and calculate the moles of Ag+Ag^+ and Cl−Cl^- present in each mixture. [2]
b
Explain why the mass of precipitate increases from mixture 1 to mixture 3, then decreases from mixture 3 to mixture 5. [2]
c
Two ionic equations are proposed:

Equation 1: Ag+(aq)+Cl−(aq)→AgCl(s)Ag^+(aq) + Cl^-(aq) \rightarrow AgCl(s)

Equation 2: 2Ag+(aq)+2Cl−(aq)→2AgCl(s)2Ag^+(aq) + 2Cl^-(aq) \rightarrow 2AgCl(s)

Evaluate which equation correctly represents the reaction, using the experimental data to justify your reasoning. [2]
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8QuestionCombination and Decomposition ReactionsAssessment Practice
8 marks~12 minCriterion D
A student heats copper(II) carbonate, CuCO3\text{CuCO}_3, strongly in an open crucible. The reaction is:

CuCO3(s)→CuO(s)+CO2(g)\text{CuCO}_3(s) \rightarrow \text{CuO}(s) + \text{CO}_2(g)

The student records the following data:

Mass of empty crucible: 25.00 g
Mass of crucible + CuCO3\text{CuCO}_3 before heating: 30.00 g
Mass of crucible + contents after heating: 28.16 g

Molar masses (g/mol): Cu = 63.55, C = 12.01, O = 16.00
a
Calculate the expected mass loss when 5.00 g of CuCO3\text{CuCO}_3 fully decomposes. [3]
b
Deduce whether the experimental data supports the hypothesis that CuCO3\text{CuCO}_3 has undergone a decomposition reaction. [2]
c
Evaluate the suitability of using an open crucible in this experiment, considering both the validity of the mass measurements and one limitation this setup introduces. [3]
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9QuestionCorrosion and Methods of preventionAssessment Practice
6 marks~9 minCriterion C
A student investigates rusting by placing identical iron nails in four environments for 5 days, then measuring mass gain.

EnvironmentMass gain:
Dry air (calcium chloride desiccant)0 mg
Boiled water with oil layer1 mg
Saltwater (3% NaCl)45 mg
Acidic solution (pH 4)38 mg


Hypothesis: both oxygen and water are necessary for iron to rust.
a
Identify which two environments act as controls for the hypothesis and state the variable each one eliminates. [2]
b
Explain why the saltwater environment produces a greater mass gain than the acidic solution, despite both containing oxygen and water. [2]
c
Evaluate the validity of the hypothesis using all four results. In your response, account for the 1 mg anomaly and discuss whether ions change the fundamental requirements for rusting. [2]
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10QuestionElectrochemical CellsAssessment Practice
3 marks~5 minCriterion B
The table below shows data recorded from five electrochemical cells, each formed by connecting two different metal–metal ion half-cells.

Difference in E⊖E^\ominus between the two metals (V): 0.10, 0.30, 0.50, 0.70, 0.90

Measured cell potential (V): 0.15, 0.45, 0.75, 1.05, 1.35
a
Describe the trend shown by the data. [1]
b
Explain why a greater difference in E⊖E^\ominus between two metals produces a higher cell potential. [1]
c
A student claims that doubling the difference in E⊖E^\ominus will always double the cell potential. Analyse whether the data support this claim, and identify one real-world factor that could cause a deviation from this pattern. [1]

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11QuestionCorrosion and Methods of preventionAssessment Practice
4 marks~6 minCriterion D
A coastal town attaches zinc blocks to steel piers to prevent corrosion. Over time, zinc blocks dissolve, releasing Zn2+Zn^{2+} ions into the surrounding seawater. Marine biologists have recorded declining invertebrate populations near the piers and are concerned about long-term ecosystem health.
a
Explain why zinc protects the steel pier from corrosion. [1]
b
Explain how Zn2+Zn^{2+} ions released into seawater could harm aquatic organisms. [1]
c
Evaluate whether the protective benefit of sacrificial zinc anodes outweighs the environmental cost to the local marine ecosystem. [2]
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12QuestionFormation and Diagrams of Covalent BondsAssessment Practice
3 marks~5 minCriterion B
The table below shows bond lengths and bond energies for four covalent bonds.

BondH–HH–FH–ClH–Br
Bond length (pm)7492127141
Bond energy (kJ mol−1^{-1})436569431366
a
Describe the general relationship between bond length and bond energy shown by the data. [1]
b
Explain this relationship in terms of electron cloud overlap. [1]
c
The H–F bond does not follow the general trend. Analyse why H–F has a higher bond energy than H–H, despite being only slightly shorter. [1]

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13QuestionFormation and Diagrams of Covalent BondsAssessment Practice
3 marks~5 minCriterion C
Two electron dot diagrams for a water molecule (H2_2O) are shown below.

Diagram A: H  ⁣: ⁣O⋅⋅⋅⋅ ⁣ ⁣: \,\colon\!\overset{\displaystyle\cdot\cdot}{\underset{\displaystyle\cdot\cdot}{\text{O}}}\!\colon\,H — oxygen shows 4 electron pairs (8 valence electrons total).

Diagram B: H  ⁣: ⁣O⋅⋅ ⁣ ⁣: \,\colon\!\overset{\displaystyle\cdot\cdot}{\text{O}}\!\colon\,H — oxygen shows 3 electron pairs (6 valence electrons total).
a
Identify which diagram correctly represents H2_2O. [1]
b
Explain why the other diagram violates the octet rule, referring to the electron arrangement around oxygen. [2]
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14QuestionBond strength, melting points and conductivityAssessment Practice
6 marks~9 minCriterion D
A city council is choosing between copper and aluminium for new power transmission lines. Engineers record the following data:

Copper: melting point 1085 ∘C1085\ ^\circ\text{C}; conductivity ≈58×106 S m−1\approx 58 \times 10^6\ \text{S m}^{-1}
Aluminium: melting point 660 ∘C660\ ^\circ\text{C}; conductivity ≈35×106 S m−1\approx 35 \times 10^6\ \text{S m}^{-1} (approximately 60\% of copper's value)

Copper is denser and more expensive to mine; aluminium is lighter and cheaper but requires large amounts of electricity to refine from bauxite ore.
a
Explain how metallic bond strength accounts for the difference in melting points between copper and aluminium. [2]
b
Discuss one societal benefit and one environmental drawback for each metal as a transmission-line material. [2]
c
Evaluate the limitations of using only melting point and conductivity data to decide which metal the council should choose. [2]
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15QuestionState Symbols in Chemical ReactionsAssessment Practice
8 marks~12 minCriterion B
Consider the following balanced equations for the reactions of elements with oxygen:

2Mg(s)+O2(g)→2MgO(s)2\text{Mg(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{MgO(s)}

2Ca(s)+O2(g)→2CaO(s)2\text{Ca(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{CaO(s)}

4Na(s)+O2(g)→2Na2O(s)4\text{Na(s)} + \text{O}_2\text{(g)} \rightarrow 2\text{Na}_2\text{O(s)}

C(s)+O2(g)→CO2(g)\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]
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16QuestionWord Equations and Symbol EquationsAssessment Practice
3 marks~5 minCriterion C
When calcium carbonate is heated, it undergoes thermal decomposition:

CaCO3(s)→CaO(s)+CO2(g)CaCO_3(s) \rightarrow CaO(s) + CO_2(g)

The graph below shows the mass of a CaCO3CaCO_3 sample recorded at regular intervals during heating.
a
Describe the trend in the rate of reaction as time progresses. [1]
b
Explain why the rate of reaction decreases as heating continues. [1]
c
The graph shows the mass becoming constant before all the fuel in the burner is consumed. Analyse what this indicates about the CaCO3CaCO_3 sample, and explain why no further mass change occurs even though heating continues. [1]
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17QuestionWriting Chemical Formulas of CompoundsAssessment Practice
6 marks~9 minCriterion D
Two ingredients commonly found in personal care products are listed below.

Sodium lauryl sulfate (SLS): C12H25SO4NaC_{12}H_{25}SO_4Na
Triclosan: C12H7Cl3O2C_{12}H_7Cl_3O_2
a
Identify the functional group present in SLS and the halogen element present in triclosan. [2]
b
Deduce how the molecular structure of each compound influences its persistence in the environment. Refer to specific structural features in your answer. [2]
c
Evaluate the limitations of current safety assessments for triclosan, considering its potential for bioaccumulation and endocrine disruption. [2]
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18QuestionBalancing Simple Chemical EquationsAssessment Practice
6 marks~9 minCriterion B
When a hydrocarbon burns completely in excess oxygen, the only products are carbon dioxide (CO2CO_2) and water (H2OH_2O). The table below shows combustion data for four alkanes.

HydrocarbonCH4CH_4C2H6C_2H_6C3H8C_3H_8C4H10C_4H_{10}
CO2CO_2 molecules produced1234
H2OH_2O molecules produced2345
a
Deduce the relationship between the molecular formula of a hydrocarbon and the number of CO2CO_2 and H2OH_2O molecules produced during complete combustion. [2]
b
Predict the number of CO2CO_2 and H2OH_2O molecules produced when one molecule of pentane (C5H12C_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]

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19QuestionBalancing Simple Chemical EquationsAssessment Practice
3 marks~5 minCriterion C
During the decomposition of hydrogen peroxide, oxygen gas is collected over time under two conditions: with manganese dioxide catalyst (Line A) and without catalyst (Line B).

2 H2O2 (aq)→2 H2O (l)+O2 (g)2\,H_2O_2\,(aq) \rightarrow 2\,H_2O\,(l) + O_2\,(g)

Graph data:

Time (s): 0, 10, 20, 30, 60, 90

Mass of O2O_2 produced (g): 0, 0.2, 0.4, 0.6, 0.8, 1.0

Line A reaches a plateau of 1.0 g at 30 s. Line B reaches a plateau of 1.0 g at 90 s.
a
Identify which line represents the catalysed reaction. [1]
b
Explain how the graph supports your identification in part (a). [1]
c
Both lines reach the same final mass of 1.0 g. Analyse what this tells you about the role of a catalyst in this reaction. [1]
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20QuestionBalancing Simple Chemical EquationsAssessment Practice
4 marks~6 minCriterion D
A factory near a residential area burns methane (CH4CH_4) for electricity generation. Complete combustion produces carbon dioxide and water, but incomplete combustion also occurs, releasing carbon monoxide (COCO) and soot (carbon particles).

CH4+2O2→CO2+2H2OCH_4 + 2O_2 \rightarrow CO_2 + 2H_2O
a
Construct the balanced equation for the incomplete combustion of methane that produces only carbon monoxide and water. [1]
b
Discuss the environmental and health implications of incomplete combustion for the nearby residential community, referring to both products of incomplete combustion and their effects on air quality and human health. [3]
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