Higher Chemistry Unit 1 Chemical Changes and Structures

Section 2 Structure and Bonding Revision Questions

1. Which type of bonding is never found in elements?A MetallicB London dispersion forcesC Polar Covalent D Non-Polar Covalent

2. In which of the following molecules will the chlorine atom carry a partial positive charge (ᵹ+)?

A Cl - BrB Cl - ClC Cl - FD Cl - I

3. Which of the following is not an example of a Van der Waals’ force? A Covalent bondingB Hydrogen bondingC London dispersion forcesD Permanent dipole-permanent dipole interactions

4. The diagram shows the melting points of successive elements across a period in the Periodic Table.

Which of the following is a correct reason for the low melting point of element Y? A It has weak ionic bondsB It has weak covalent bondsC It has weakly-held outer electronsD It has weak forces between molecules

5. Which of the following elements would have the strongest London dispersion forces?A ArgonB ChlorineC Nitrogen

D Oxygen

6. The shapes of some common molecules are shown below and each contains at least on polar bond. Which molecule is non-polar?

7. Caryophyllene is a natural product which can be extracted from clove oil using a solvent.

Which of the following would be the best solvent for extracting caryophyllene?

A HexaneB Hexanal C Hexan-2-olD Hexan-3-one

8. Which type of bonding is never found in elements?

A MetallicB London dispersion forcesC Polar covalentD Non-polar covalent

9. The diagram shows the melting points of successive elements across a period in the Periodic Table

Which of the following is a correct reason for the low melting point of element Y?

A It has weak ionic bondsB It has weak covalent bondsC It has weakly-held outer electronsD It has weak forces between molecules

10. The structures for molecules of four liquids are shown below. Which liquid will be the most viscous?

11. In which of the following molecules will the chlorine atom carry a partial positive charge (ᵹ+)?

A Cl - BrB Cl - ClC Cl - FD Cl - I

12. Erythrose can be used in the production of a chewing gum that helps prevent tooth decay

Which of the following compounds will be the best solvent for erythose?

13. Which line in the table represents the solid in which only London dispersions forces are overcome when the substance melts?

14. Coniceine is a deadly poison extracted from the plant hemlock

Which of the following would be the best solvent for coniceine?

A Propanoic acidB Propan-1-olC HeptaneD Water

15. Vanillin and zingerone are flavour molecules.

Which line in the table correctly compares the properties of vanillin and zingerone?

More soluble in water

More volatile

A Vanillin VanillinB Vanillin ZingeroneC Zingerone VanillinD Zingerone Zingerone

These questions are taken from the old Higher paper. They are useful for checking understanding, but be aware the question style and structure, as well as how they are marked, may be different from the Cfe paper.16. Hydrogen will form a non-polar covalent bond with an element which has an electronegativity value of

A 0.9B 1.5C 2.2D 2.5

17. Which property of a chloride would prove that it contained ionic bonding?A It conducts electricity when moltenB It is soluble in a polar solvent

C It is solid at room temperatureD It has a high boiling point

18. When two atoms form a non-polar covalent bond, the two atoms must have

A the same atomic sizeB the same electronegativityC the same ionisation energy D the same number of outer

electrons19. In which of the following liquids does hydrogen bonding occur?

A Ethanoic acidB Ethyl ethanoateC HexaneD Hex-1-ene

20. Which line in the table shows the correct entries for tetrafluoroethene

Polar Bonds? Polar Molecules?A Yes YesB Yes NoC No NoD No Yes

21. Which of the following compounds has the greatest ionic character?

A Caesium fluorideB Caesium iodideC Sodium fluorideD Sodium iodide

22. The two hydrogen atoms in a molecule of hydrogen are held together by

A a hydrogen bondB a polar covalent bondC a non-polar covalent bond

23. In which of the following compounds would hydrogen bonding not occur?

24. Some covalent compounds are made up of molecules that contain polar bonds but the molecules are overall non-polar. Which of the following covalent compounds is made up of non-polar molecules?

A Ammonia B WaterC Carbon tetrachlorideD Hydrogen fluoride

24. In which of the following liquids does hydrogen bonding occur?

A Ethanol B Ethyl ethanoateC HexaneD Pent-1-ene

25. The shapes of some common molecules are shown. Each molecule contains at least one polar covalent bond.

26. Which of the following chlorides is likely to have least ionic character?

A BeCl2B CaCl2C LiClD CsCl

27. Which of the following chlorides is most likely to be soluble in tetrachloromethane, CCl4?

A Barium chlorideB Caesium chlorideC Calcium chlorideD Phosphorus chloride

28. Which of the following compounds exists as discrete molecules?

A Sulfur dioxideB Silicon dioxideC Aluminium oxideD iron (II) oxide

29. An element (melting point above 3000°C) forms an oxide which is a gas at room temperature. Which type of bonding is likely to be present in the element?

A MetallicB Polar covalent C Non-polar covalentD Ionic

30. Which of the following compounds has polar molecules?

A CO2B NH3C CCl4D CH4

31. Fuels containing alcohols have a tendency to absorb water, which can cause the engine to rust. Water is absorbed by alcohols due to hydrogen bonds forming between the alcohol and water molecules. In the space below, use a dotted line to show a hydrogen bond forming between the a water molecule and 2-methylpropan-1-ol

1

32. Cyanoacrylate adhesives are a range of high performance “super glues”. In its liquid form, super glue consists of cyanoacrylate monomers that rapidly polymerise in the presence of water to form a strong resin that joins two surfaces together. Cyanoacrylates have the general structure

where R is a hydrocarbon group, eg -CH3.

If used incorrectly, super glue can rapidly cause your fingers to stick together.

a) Suggest why super glue reacts rapidly on the surface of the skin.1

b) Super glue can be removed from the skin using propanone as a solvent.1

Name the main type of van der Waals’ forces that would be formed between propanone and super glue.

33. Volcanoes produce a variety of molten substances, including sulfur and silicon dioxide. a) Complete the table to show the strongest type of attraction that is broken when each substance melts. 2

Substance Melting point (°C)

Strongest type of attraction broken when substance melts

Sulfur 113Silicon dioxide 1610

b) Volcanic sulfur can be put to a variety of uses. One such use involves reacting sulfur with phosphorus to make a compound with formula P4S3.

(i) Draw a possible structure for P4S3. 1

ii) The melting point of sulfur is much higher than that of phosphorus. Explain fully, in terms of the structures of sulfur and phosphorus molecules and the intermolecular forces between molecules of each element, why the melting point of sulfur is much higher than that of phosphorus.

3

34. Sherbet is a sweet powder that fizzes on the tongue.

(a) A sherbet contains citric acid. Explain why citric acid is very soluble in water.1

b) Explain the difference in polarities of ammonia and trichloramine molecules.2

35. Starch is a polymer of glucose. It can exist in two forms: a linear form, amylase and a branched form, amylopectin. Part of the structure of each is shown. Each hexagon in the structures represents a glucose unit. To make soft and moist bread, starch must separate and disperse into water. Amylopectin separates and disperses into water much more easily than amylose. Suggest why this is the case. 1

36. The boiling point of hydrogen fluoride, HF, is much higher than the boiling point of F2.H – F F – F

Boiling point: 19.5°C Boiling point: -188°C

Explain fully why the boiling point of hydrogen fluoride is much higher than the boiling point of fluorine. In your answer you should mention the intermolecular forces involved and how they

arise. 3

37. When conditioner containing behenic acid is applied to hair, the behenic acid molecules make strong intermolecular hydrogen bonds to the keratin protein molecules. On the diagram below use a dotted line to show one hydrogen bond that could be made between a behenic acid molecule and the keratin. 1

38. The structures below show molecules that contain chlorine atoms. The compounds shown above

are not very soluble in water. Trichloromethane is around ten times more soluble in water than tetrachloromethane.

Explain clearly why trichloromethane is more soluble in water than tetrachloromethane. Your answer should include the names of the intermolecular forces involved.

3

39. Hydrogen sulfide gas produced from iron(II) sulfide is often contaminated with hydrogen gas and gaseous arsenic compounds.

(i) Arsenic(III) sulfide is an orange-yellow powder which is insoluble in water. Below 310 °C it can sublime, turning from a solid to a gas. Name the type of bonding and structure present in arsenic(III) sulfide.

40. Liquid hydrogen sulfide has a boiling point of −60 °C.Name the strongest type of intermolecular force present in liquid hydrogensulfide and state how this force arises. 2

41. Methanamide, HCONH2, is widely used in industry to make nitrogen compounds.It is also used as a solvent as it can dissolve ionic compounds. Why is methanamide a suitable solvent for ionic compounds?

1

42. Electronegativity values can be used to predict the type of bonding present in substances. The type of bonding between two elements can be predicted using the diagram below. a) Using the information in the diagram, state the highest average electronegativity found in ionic compounds.

1

b) The diagram can be used to predict the bonding in tin iodide. 1Electronegativity of tin = 1.8Electronegativity of iodine = 2.6Average electronegativity= 2.2Difference in electronegativity = 0.8Predict the type of bonding in tin iodide.

c) The electronegativities of arsenic and chlorine are shown below. 1

Electronegativity of arsenic = 2.2Electronegativity of chlorine = 3.0

Place a small cross on the diagram to show the position of arsenic chloride. Show calculations clearly.

These questions are taken from the old Higher paper. They are useful for checking understanding, but be aware the question style and structure, as well as how they are marked, may be different from the Cfe paper.

43. Triethanol amine and triisopropyl amine are bases used to neutralise acidic compounds in the hairspray to prevent damage to the hair. In terms of the intermolecular bonding present,

explain clearly why triethanol amine has a much higher boiling point than triisopropyl amine. 2

44. Hydrogen cyanide, HCN, is highly toxic. Information about hydrogen cyanide is given in the table.

StructureMolecular Mass 27

Boiling point 26°C

Although hydrogen cyanide has a similar molecular mass to nitrogen, it has a much higher boiling point. This is due to the permanent dipole-permanent dipole attractions in liquid hydrogen cyanide. What is meant by permanent dipole-permanent dipole attractions? Explain how they arise in liquid hydrogen cyanide.

2

45. Hydrogen gas has a boiling point of -253°C. Explain clearly why hydrogen is a gas at room temperature. In your answer you should name the intermolecular forces involved and indicate how they arise. 2

46. Compared to other gases made up of molecules of similar molecular masses, ammonia has a relatively high boiling point. In terms of the intermolecular bonding present, explain clearly why ammonia has a relatively high boiling point.

2