Chemistry of Life

Question 1

What is the difference between covalent and ionic bonding?

Answer 1

Covalent bonding occurs when only non-metals (such as carbon, hydrogen, and oxygen) share electrons to gain a full valence shell. Whereas in ionic bonding metals donate electrons to non-metals to complete their outer shells.

Question 2

Why do atoms form covalent bonds?

Answer 2

To complete their valence shell

Question 3

How do non-metals gain electrons?

Answer 3

Either through ionic bonding where a metal donates electrons, or through covalent bonding where non-metals share electrons

Question 4

What is the difference between single, double, and triple covalent bonds? Give an example of compounds that contain each type of bond.

Answer 4

Single - atoms share two electrons (one from each atom) eg. methane
Double - atoms share four electrons (two from each atom) eg. ethene
Triple - atoms share six electrons (three from each atom) eg. propyne

Question 5

Know how to identify whether a compound will have single, double, or triple covalent bonds.

Answer 5

Number of elements.

Question 6

Why is carbon so important?

Answer 6

• Carbon atoms can form so many compounds because they can form strong covalent with four other atoms.
• Carbon can also link together in long chains or rings
• Carbon atoms bond to Hydrogen, Nitrogen, Oxygen, Phosphorus, and Sulfur atoms, as well as other carbon atoms.
• Carbon to carbon bonds can be single, double, or triple covalent bonds.

Question 7

What are hydrocarbons?

Answer 7

When a compound contains only carbon and hydrogen atoms

Question 8

Name the three families of hydrocarbons

Answer 8

Alkanes, Alkenes, and Alkynes

Question 9

What are the differences and similarities between alkanes, alkenes, and alkynes?

Answer 9

Alkanes contain only single carbon-carbon bonds and are saturated, while alkenes which contain double bonds and alkynes which contain triple bonds are unsaturated. They’re all hydrocarbons.

Question 10

Know what an alcohol and its hydroxyl group is.

Answer 10

Alcohols are organic compounds that have a hydrogen atom replaced by a functional group called hydroxyl group -OH

Question 11

Know what a carboxylic acid and its carboxyl group is.

Answer 11

Carboxylic acids have a functional group called a carboxyl group -COOH
(the carbon has a double bond to one oxygen atom, and a single bond to the second oxygen which is bonded to a hydrogen atom)

Question 12

Describe a combustion reaction.

Answer 12

A reaction between a substance (Fuels eg. hydrocarbons and small alcohols) and oxygen to release useful energy (most of the energy is released as heat, but light energy is also released)

Question 13

Describe the difference between carbon dioxide and carbon monoxide.

Answer 13

Carbon dioxide has two oxygens whereas carbon monoxide has one.

Question 14

Know why incomplete combustion can occur instead of complete combustion.

Answer 14

If there is a shortage of oxygen when a hydrocarbon fuel is burned. (complete needs about 21% of the air to be oxygen)

Question 15

Write the general word equation for a complete and an incomplete combustion reaction.

Answer 15

Complete
hydrocarbon or alcohol + oxygen –> carbon dioxide + water
Incomplete
hydrocarbon or alcohol + oxygen –> carbon monoxide + water

Question 16

What is an exothermic reaction? Give an example.

Answer 16

A reaction (reactions involve a chemical change) which transfers heat energy to the surroundings eg. lighting firewood

Question 17

What is an exothermic process? Give an example.

Answer 17

A process (which refers to a physical change) which transfers heat energy to the surroundings eg. making ice cubes

Question 18

How can you identify an exothermic reaction?

Answer 18

Identify whether the substance has had a chemical change and released heat into the surroundings

Question 19

What is the difference between a reaction and a process?

Answer 19

A reaction involves a chemical change, whereas a process refers to a physical change

Question 20

What is the definition of a fuel?

Answer 20

A substance that produces useful energy when it undergoes a chemical reaction.

Question 21

What are fossil fuels? Give three examples of fossil fuels.

Answer 21

Fuels that have been obtained from plant and animal matter that has been buried and subjected to heat and pressure over millions of years. eg. coal, oil (or petroleum), and natural gas (CON)

Question 22

Briefly describe the process of coal, petroleum, and natural gas formation.

Answer 22

Coal - before the dinosaurs many plants died in swamps and over millions of years the plants were buried under water and dirt. Heat and pressure turned the dead plants into coal.
Oil and Natural Gas - Small organisms in the ocean millions of years ago died and were buried on the ocean floor, over millions of years the remains were buried deeper and deeper by silt and sand. The enormous heat and pressure turned them into oil and gas.

Question 23

Fossil fuels are described as non-renewable resources. Using examples, explain the meaning of non-renewable resources and renewable resources.

Answer 23

A non-renewable resource is a natural resource that is used up faster than it can be made by nature. Such as coal which takes millions of years to form and burn up within hours. Renewable resources are constantly replenished such as sunlight and wind.

Question 24

Name and give the chemical formulas of two greenhouse gases.

Answer 24

Methane - CH4
Carbon dioxide - CO2

Question 25

Be able to briefly describe the greenhouse effect.

Answer 25

The more greenhouse gases in the atmosphere, the more radiation (heat) is absorbed. This is re-emitted back towards Earth, causing Earth’s temperature to increase.

Question 26

Explain the link between fossil fuel use and the enhanced greenhouse effect.

Answer 26

Burning fossil fuels produces carbon dioxide and the more carbon dioxide released into the atmosphere the more the greenhouse effect is enhanced.

Question 27

What are biofuels?

Answer 27

Fuels that are produced over a short time span from biomass eg. Biodiesel from vegetable oils, bioethanol from plant material and biogas from farm waste.

Question 28

List the advantages of biofuels over fossil fuels and some disadvantages.