Chemistry Hydrocarbons and Gases in the Atmosphere

List the Fractions of crude oil in ascending order of the number of carbons

Refinery gases, gasoline, kerosene, diesel, fuel oil, bitumen

Use of refinery gases

Domestic heating and cooking

Use of gasoline

Fuel for cars

Use of kerosene

Fuel for aircraft

Use of diesel

Fuel for some cars and larger vehicles

Use of fuel oil

Fuel for ships and power stations

Use of bitumen

Surface roads and roofs

Explain how crude oil is seperated into fractions in fractional distillation (5 steps)

1) Crude oil is heated until most of it turns into gas
2) The gases enter a fractionating column and the liquid bitumen is drained off the bottom
3) There is a concentration gradient in the column.
4) Longer hydrocarbons with higher boiling points condense and drain out lower in the column.
5) Shorter hydrocarbons have lower boiling points so they condense higher up in the column.

3 conditions required for cracking

Vaporized hydrocarbons, powdered catalyst, 600 - 700 C

What catalyst is used in cracking?

silica or alumina

Equation for cracking

long chain hydrocarbon -> shorter alkane molecule + alkene

Equation for complete combustion of hydrocarbons

hydrocarbon + oxygen -> carbondioxide + water

Equation for incomplete combustion of hydrocarbons

hydrocarbon + oxygen -> carbon monoxide + soot (carbon) + water

Why is carbon monoxide dangerous?

It binds with haemoglobin and reduces its ability to carry oxygen, leading to a coma or death.

How is SO2 formed?

Sulfur impurities released when burning hydrocarbon fuel react with oxygen to form SO2..

How is NO2 and NO formed?

Nitrogen oxides are created when the temperature is high enough for the nitrogen and oxygen in the air to react.

How is acid rain formed?

When sulfur dioxide and nitrogen oxides mix with water vapor in clouds they form dilute sulfuric acid and nitric acid which falls as acid rain.

Effect of acid rain

Causes lakes to become acidic, Damages wildlife

Empirical formula

The simplest whole number ratio of atoms of each element present in a compound

Molecular formula

The actual number of atoms of each element in a molecule

Displayed formula

Shows how all the atoms are arranged, and all the bonds between them.

Structural formula

a formula that shows the arrangement of atoms in the molecule of a compound

Homologous series

A grouop of compounds that can all be represented by the same general formula.

Functional group

A functional group is a group of atoms that determine how a compound typically reacts.

What is required for a substitution reaction to occur?

UV light

% of nitrogen in the atmosphere

78%

% of oxygen in the atmosphere

21%

% of argon in the atmosphere

1%

How can phosphorus and iron be used to calculate the percentage of oxygen in the air?

Both phosphorus and iron react with the oxygen in the air to form oxides, which removes oxygen from the air. The percentage change in the volume of air can be calculated to find the percentage of oxygen in the air.

% of carbondioxide in the atmosphere

0.04%

How does increase in percentage of carbondioxide cause environmental problems?

Carbondioxide is a greenhouse gas that traps heat in the atmosphere causing global warming. It can also make oceans more acidic.

Combustion

rapid reaction between a substance and oxygen that releases heat and light energy

use of oxygen

respiration

use of nitrogen

air inside chips bag

use of argon

light bulbs

use of carbondioxide

fizzy drinks

use of water

cells

most abundant trace gas in the atmosphere

argon

Why do larger hydrocarbons have higher boiling points in terms of their structures?

Larger hydrocarbons have stronger intermolecular forces and thus more energy is required to seperate their molecules.

Why is it necessary to convert long-chain alkanes into shorter-chain alkanes?

Short-chain alkanes are easier to ignite and use as fuel, and also there is less supply of short-chain alkanes whereas long-chain alkanes are in surplus.