Chemistry Must Know Facts EDEXCEL IGCSE

What is the mass of a proton?

1 amu (atomic mass unit)

What is the mass of a neutron?

1 amu (atomic mass unit)

What is the mass of an electron?

Approximately 1/1840 amu

What is the charge on a proton?

+1

What is the charge on an electron?

-1

What is the charge on a neutron?

0

What is the state symbol for something dissolved in water?

(aq)

What is a covalent bond?

The electrostatic attraction between 2 nuclei and a shared pair of electrons between them.

What types of element do covalent bonds form between?

Two non-metals.

What is an ionic bond?

The electrostatic attraction between 2 oppositely charged ions.

What types of element do ionic bonds form between?

A non-metal and a metal.

What is the formula of ammonia?

NH₃

What is the formula and charge of a nitrate ion?

NO₃ -

What is the formula and charge of a carbonate ion?

CO₃ 2-

What is the formula and charge of an ammonium ion?

NH₄ +.

What is the formula and charge of a zinc ion?

Zn 2+.

What is the formula and charge of a silver ion?

Ag+.

What is the formula and charge of a hydroxide ion?

OH-.

What is the formula and charge of a sulphate ion?

SO₄ 2-.

What state is chlorine at room temperature?

Gas.

What colour is chlorine at room temperature?

Green.

What state is bromine at room temperature?

Liquid.

What colour is bromine at room temperature?

Brown.

What state is iodine at room temperature?

Solid.

What colour is iodine at room temperature?

Grey.

What percentage of air is nitrogen?

78%.

What percentage of air is oxygen?

21%.

What percentage of air is argon?

0.9%.

What percentage of air is carbon dioxide?

0.04%.

Which 2 main gases dissolve in rain to cause acid rain?

Nitrogen Dioxide and Sulphur Dioxide.

What acid is formed when sulphur dioxide dissolves in rain?

Sulphurous Acid.

What is seen when copper carbonate decomposes?

Green powder (CuCO₃) forms black powder (CuO).

How do I test for Carbon Dioxide and what result would I get?

Test: Bubble through limewater. Result: White precipitate

How do I test for Water and what result would I get?

Test: Add anhydrous copper sulphate. Result: Turns from white to blue.

How do I test to see if water is pure?

Test: Heat it up. Result: It will boil at exactly 100°C.

How do I test for Hydrogen Gas and what result would I get?

Test: Add lit splint. Result: Squeaky pop.

How do I test for Calcium Ions and what result would I get?

Test: Flame Test. Result: Orange red / Brick red flame.

How do I test for Lithium Ions and what result would I get?

Test: Flame Test. Result: Red flame.

Flame test for Copper (II) ions and what result would I get?

Test: Flame Test. Result: Blue-green flame.

How do I test for Sodium Ions and what result would I get?

Test: Flame Test. Result: Yellow flame.

How do I test for Bromide ions and what result would I get?

Test: Add dilute nitric acid then silver nitrate. Result: Cream / off-white ppt.

How do I test for Iodide Ions and what result would I get?

Test: Add dilute nitric acid then silver nitrate. Result: Yellow ppt.

How do I test for Carbonate Ions and what result would I get?

Test: Add nitric acid and bubble gas given off through limewater. Result: White ppt.

How do I test for Sulphate Ions and what result would I get?

Test: Add dilute hydrochloric acid then barium chloride. Result: White precipitate.

How do I test for Ammonium Ions and what result would I get?

Test: Add sodium hydroxide and test gas given off with damp red litmus paper. Result: Turns blue.

How do I test for Chloride Ions and what result would I get?

Test: Add dilute nitric acid then silver nitrate. Result: White ppt.

How do I test for Oxygen gas?

Test: Add a glowing splint. Result: Relights.

How do I test for Chlorine Gas and what result would I get?

Test: Damp blue litmus paper. Result: Turns red then bleaches.

How do I test for Ammonia and what result would I get?

Test: Add damp red litmus paper. Result: Turns blue.

How do I test for Iron (II) Ions and what result would I get?

Test: Add NaOH. Result: Green ppt.

How do I test for Iron (III) Ions and what result would I get?

Test: Add sodium hydroxide. Result: Orange-brown precipitate

How do I test for Copper (II) Ions and what result would I get?

Test: Add NaOH. Result: Blue ppt.

How do I test for Potassium Ions and what result would I get?

Test: Flame Test. Result: Lilac Flame.

What color is litmus in acidic conditions?

Red.

What color is litmus in alkaline conditions?

Blue.

What color is phenolphthalein in acidic conditions?

Colourless.

What color is phenolphthalein in alkaline conditions?

Pink.

What color is methyl orange in acidic conditions?

Red.

What color is methyl orange in alkaline conditions?

Yellow.

What are the solubility rules for nitrates?

All nitrates are soluble.

What are the solubility rules for carbonates?

All carbonates are insoluble apart from group 1 and ammonium compounds.

What is an ore?

A natural material from which a metal or valuable mineral can be profitably extracted.

What 2 things does iron need to rust?

Water and oxygen.

Give 3 ways of preventing iron from rusting.

Sacrificial protection, painting, galvanising.

Name the 6 main fractions of crude oil from smallest to largest.

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

Give a use of the refinery gases fraction.

Heating homes & cooking.

Give a use of the gasoline fraction.

Petrol for cars.

Give a use of the kerosene fraction.

Jet fuel.

Give a use of the diesel fraction.

Fuel for cars and trucks.

Give a use of the fuel oil fraction.

Fuel for ships and heating.

Give a use of the bitumen fraction.

Tar for roads.

What temperature is required for catalytic cracking?

600 - 700°C.

What catalyst is required for catalytic cracking?

Silicon dioxide or aluminium oxide.

Give the names of the 6 smallest alkanes starting with the smallest.

Methane, Ethane, Propane, Butane, Pentane, Hexane.

Give the general formula for the alkanes.

C_nH_2n+2.

Name the products of complete combustion.

Water and Carbon Dioxide.

Name the products of incomplete combustion.

Water, Carbon Monoxide (and possibly some carbon as soot).

Give the general formula for the alkenes.

C_nH_2n.

What catalyst is used to produce ethanol from ethene and steam?

Phosphoric Acid.

What temperature is used to produce ethanol from ethene and steam?

300°C.

What pressure is used to produce ethanol from ethene and steam?

60-70 atm.

What temperature is used to produce ethanol from the fermentation of sugars?

30°C.

How can ethanol be converted to ethanoic acid?

Add potassium dichromate and dilute sulphuric acid then heat.

What is seen when potassium dichromate reacts with an alcohol?

Orange potassium dichromate turns green.

How is ethanol naturally converted to ethanoic acid?

Microbes in the air react it with oxygen.

How can a carboxylic acid and an alcohol be converted to an ester?

Heat with a sulphuric acid catalyst.

Give two uses of esters.

Food flavourings and perfumes.

Give 3 uses of polymers.

Making plastic bags, window frames, furniture.

Give 2 environmental problems with polymers.

They are inert so don't biodegrade and produce toxic gases when burned.

What is seen when sulphur burns?

Blue flames and fumes of sulphur dioxide gas.

What is seen when magnesium burns?

White flame and white magnesium oxide powder.

In order to add Bromine to an Alkane you need what?

UV

To test if something is a double bond you add what?

Add bromine water; if double bond goes from orange to colourless.

Alkanes

C_nH_2n+2

Alkenes

C_nH_2n, C=C

Alcohols

C_nH_2n+1OH

Carboxylic Acids

C_nH_2n+1COOH

Esters

C_nH_2nO₂ -COO-

Addition Polymerisation

Happens in Alkenes.
Requires double carbon bond.

Colour of flourine

pale green/yellow and gas at room temp