Chemistry Acids, Alkalis, Making Salts

Litmus in an acid

Litmus in an acid

Red

Litmus in an alkali

Blue

Phenolphthalein in an acid

Colourless

Phenolphthalein in an alkali

Pink

Methyl Orange in an acid

Red

Methyl Orange in an alkali

Yellow

Universal indicator in weak and strong acid

Yellow, Red

Universal indicator in a weak and strong alkali

Pale Blue, Purple

What are acids in an aqueous solution?

A source of hydrogen ions

What are alkalis in an aqueous solution?

A source of hydroxide ions

What is the relation ship between acids and alkalis?

An alkali can neutralise an acid

What is an neutralisation reaction?

A neutralisation reaction is where the protons donated by the acid react with the hydroxide ions to remove the hydrogen ions and form water

Why do acids in water dissociate to give hydrogen ions?

Acids in water dissociate because there are strong interactions between polar water molecules and acid molecules which are also polar. Energy is given out which means the acid molecule breaks apart

Which salts are soluble?

All sodium, potassium and ammonium salts

Solubility rules of chlorides

Most are soluble except Silver Chloride and Lead Chloride

Solubility rules of sulfates

Most sulfates are soluble except Lead Sulfate, Barium Sulfate and Calcium Sulfate

Solubility rules of carbonates

Most carbonates are insoluble except Sodium Carbonate, Potassium Carbonate, and Ammonium Carbonate

Solubility rules of oxides and hydroxides

Most oxides and hydroxides are insoluble except Sodium Hydroxide, Potassium Hydroxide and Ammonium Hydroxide

What is an acid?

A proton donor

What is a base?

A proton acceptor

Observations of Magnesium reacting with Sulfuric Acid

• Magnesium is a silvery metal strip

• Immediate bubbling

• Metal eventually disappears

• Hydrogen gas is produced

Observations of Aluminium reacting with Sulfuric Acid

• Aluminium is a grey powder

• Nothing at first, as acid needs to dissolve the tough layer of aluminium oxide that forms on the aluminium, by oxidizing with the air

• After time, bubbling starts

• Solution appears cloudy

• Insufficient gas to do test

Observations of Iron reacting with Sulfuric Acid

• Iron is a dark grey powder

• Bubbles form on surface of grey powder

• Insufficient gas to do test

Observations of Copper reacting with Sulfuric Acid

• Copper is a pink brown turning

• No reaction

Observations of Copper (II) Oxide reacting with Sulfuric Acid

• Copper Oxide is black

• Reaction needs heat to start

• Rapid boiling of solution when reaction starts

• Solution goes to green blue colour

Observations of Calcium carbonate reacting with Sulfuric Acid

• Calcium carbonate is white small chips

• Immediate fizzing then the reaction peters out as a layer of Calcium Sulfate coats the substance which is insoluble, preventing anymore acid to react with the Calcium Sulfate

• Gas produced is CO2

Observations of Copper (II) Carbonate reacting with Sulfuric Acid

• Copper (II) Sulfate is a green powder

• Immediate fizzing

• Solution goes green blue solution

• Gas produced is CO2

What can act as bases?

Ammonia, Metal Oxides and Metal Hydroxides

What is an alkali?

An alkali is a base that is soluble in water