BondingIB MYP Sciences: Topic test

20 questions, 54 marks

IB MYP Sciences

Bonding topic test

Total 54 marks

Name

Class

Date

1
In many countries table salt has a small amount of potassium iodide, KI, added to it, because iodine is needed for a healthy thyroid gland. Potassium iodide is an ionic compound.
(a)
Which statement describes how potassium iodide forms from its atoms?
[1 mark]
AA potassium atom and an iodine atom share a pair of electrons.
BA potassium atom transfers one electron to an iodine atom.
CAn iodine atom transfers one electron to a potassium atom.
DA potassium atom and an iodine atom each lose one electron.
(b)
Which statement about solid potassium iodide is correct?
[1 mark]
AIt conducts electricity when solid.
BIt has a low melting point.
CIt is soft and easily bent.
DIt conducts electricity when dissolved in water.
(c)
A different additive is calcium iodide. Using the charges on its ions, explain why its formula is CaI₂.
[2 marks]
Total for question 1: 4 marks
2
A student in Chicago adds 1 g of manganese(IV) oxide powder to 50 cm³ of hydrogen peroxide solution and collects the oxygen gas that is produced in a gas syringe. The manganese(IV) oxide is unchanged at the end of the reaction. The volume of gas rises quickly at first, then more slowly, and levels off at 60 cm³ after 90 seconds.
(a)
What is the job of the manganese(IV) oxide?
[1 mark]
AIt is a catalyst: it speeds up the reaction and is not used up.
BIt is a reactant: it is used up as the reaction goes on.
CIt is a product: it is made in the reaction.
DIt increases the total volume of oxygen produced.
(b)
Why does the reaction slow down as the experiment goes on?
[1 mark]
AThe temperature of the mixture falls.
BThe catalyst is used up.
CThe concentration of hydrogen peroxide falls, so there are fewer collisions each second.
DThe gas syringe gets bigger.
(c)
The student repeats the experiment with the same mass of manganese(IV) oxide as one lump instead of a powder. Predict the effect on the rate of reaction and explain it.
[2 marks]
Total for question 2: 4 marks
3
A soft-drink factory in Manila adds carbon dioxide gas to its drinks under pressure. A carbon atom has four electrons in its outer shell, and an oxygen atom has six. Carbon dioxide, CO₂, is a simple molecular substance.
(a)
Describe how the atoms in a carbon dioxide molecule are held together, and how many electrons the carbon atom and each oxygen atom share.
[3 marks]
(b)
Explain, in terms of structure and bonding, why carbon dioxide is a gas at room temperature and does not conduct electricity, whereas a giant covalent structure such as diamond has a very high melting point.
[4 marks]
Total for question 3: 7 marks
4
In parts of Scandinavia, rain made acidic by sulfur dioxide from power stations lowered the pH of lake water from 6.5 to 4.5, and fish died. The authorities sprayed powdered limestone (calcium carbonate) onto the lakes from helicopters, and over several weeks the pH rose to about 6.
(a)
Explain how adding calcium carbonate raises the pH of an acidic lake. In your answer, name the type of reaction, give a word equation using hydrochloric acid as an example of the acid, say what you would observe, and describe how you would test the gas produced.
[6 marks]
(b)
Discuss and evaluate the social, economic and environmental implications of adding limestone to acidic lakes compared with reducing sulfur dioxide emissions from power stations. Finish with a justified conclusion.
[6 marks]
Total for question 4: 12 marks
5
A firework maker in Valencia burns aluminium powder in oxygen. The powder burns with a bright white light and forms aluminium oxide, a white solid, Al₂O₃.
(a)
Which is the correct balanced symbol equation for this reaction?
[1 mark]
AAl + O₂ → Al₂O₃
B2Al + 3O₂ → 2Al₂O₃
C4Al + 3O₂ → 2Al₂O₃
D2Al + O₂ → Al₂O₃
(b)
Which term describes the reaction of aluminium with oxygen?
[1 mark]
ADecomposition
BOxidation
CNeutralisation
DPrecipitation
(c)
When 2.7 g of aluminium powder burns completely in an open crucible, 5.1 g of white aluminium oxide forms. Explain why the product is heavier than the aluminium, and calculate the mass of oxygen that reacted.
[2 marks]
Total for question 5: 4 marks
6
Car batteries contain dilute sulfuric acid, H₂SO₄, which is corrosive. A mechanic in Karachi spills some on the garage floor and covers the spill with sodium carbonate powder, which fizzes. When the fizzing stops, she touches damp powder with a piece of universal indicator paper and it turns green.
(a)
Which gas is given off when the powder fizzes?
[1 mark]
AHydrogen
BOxygen
CSteam
DCarbon dioxide
(b)
What does the green colour of the indicator paper show?
[1 mark]
AThe mixture is neutral, with a pH of about 7, so the acid has been neutralised.
BThe mixture is still strongly acidic, with a pH of about 1.
CThe mixture is strongly alkaline, with a pH of about 14.
DThe mixture is weakly acidic, with a pH of about 5.
(c)
Name the salt formed in the reaction and write a word equation for the reaction between sulfuric acid and sodium carbonate.
[2 marks]
Total for question 6: 4 marks
7
An instant cold pack used by a physiotherapist in Melbourne contains water and solid ammonium nitrate. When the pack is squeezed they mix and the temperature falls from 22 °C to 4 °C. A reusable hand warmer sold in Oslo contains iron powder. When the packet is opened, the iron reacts with oxygen in the air and the temperature rises to 55 °C.
(a)
State which of the two products is exothermic and which is endothermic, giving the evidence for each, and name the type of reaction that happens in the hand warmer.
[3 marks]
(b)
A hand warmer contains 5.6 g of iron powder. After use, the powder has changed to 8.0 g of orange-brown iron(III) oxide. Explain why the mass has increased, calculate the mass of oxygen that reacted, and give one piece of evidence, other than the temperature change, that a chemical reaction has taken place.
[4 marks]
Total for question 7: 7 marks
8
A student in Stockholm investigates a bath bomb that contains citric acid and sodium hydrogencarbonate. When it is dropped into water the two substances react and carbon dioxide gas is released, so the water fizzes. The student drops one bath bomb into 250 cm³ of water at each of four temperatures and times how long it takes for the fizzing to stop. The times are 142 s at 10 °C, 95 s at 20 °C, 61 s at 30 °C and 38 s at 40 °C. Each temperature was tested once.
(a)
The student now wants to test the hypothesis that crushing the bath bomb into a powder makes the reaction faster. Plan an investigation. In your answer, state a hypothesis with a scientific reason, identify the variables, and describe a safe method.
[6 marks]
(b)
Process the student's data and evaluate her method. Finish with a justified conclusion about how temperature affects the rate of this reaction.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).