C4-Chemical Changes

What is PH?

A measure of how acidic or alkaline an aqueous solution is

What is the range of the pH scale?

0-14

What does a higher pH mean?

The more ALKALI a solution is.

What type of ions do acids release?

Hydrogen ions

What is the pH of an acid?

less than 7

What type of ions do alkalis release?

hydroxide ions

What is the pH of an alkali?

greater than 7

What is the pH of a neutral solution, and why?

pH of 7 showing a balance between H⁺ and OH⁻ ions.

What are the two types of pH measurement tools?

1. Indicators (e.g. universal indicator)

2 . Digital pH meter

What does a universal indicator do?

It changes colour across the full pH scale (0-14) to show how acidic or alkaline a solution is.

How does a pH probe work?

The pH probe is immersed in the solution, and the meter gives a reading for the pH values.

What is neutralisation?

a type of chemical reaction where an acid and base react to form salt plus water

What is the equation for a neutralisation reaction?

Acid + Base → Salt + Water.

What happens in a neutralisation reaction?

The reaction involves the transfer of H⁺ ions from the acid to the OH⁻ ions of the alkali

What is an acid?

solutions that release Hydrogen IONS (H⁺) in water.

What is a base?

A substance that can neutralise an acid

What is an alkali?

Bases that are soluble in water

What is the type of salt formed when an acid reacts with hydrochloric acid

Chloride salt

What is the type of salt formed when an acid reacts with Nitric acid?

Nitrate salt

What is the type of salt formed when an acid reacts with sulfuric acid?

Sulphate salt

What is the reaction of an acid and a metal oxide?

Acid + Metal Oxide → Salt + Water

What is the reaction of an acid and a metal hydroxide?

Acid + Metal Hydroxide → Salt + Water

Is metal carbonate a base?

Yes

What is the reaction of an acid and a metal carbonate?

Acid + Metal Carbonate → Salt + Water + Carbon Dioxide

What is the symbol equation for making copper sulphate?

H₂SO₄ + CuO → CuSO₄ + H₂O.

What is oxidation?

When metals react with oxygen and oxygen is gained in the reaction

What is reduction?

The process of extracting a metal from its oxide involves the loss of oxygen

What are the 2 types of Extraction techniques?

1. Reduction with carbon

2. Electrolysis

What metals use reduction by carbon for extraction

metals below carbon in the reactivity series: Zinc, Iron, Copper

How does reduction by carbon work?

Carbon is more reactive than metals below it, so it will remove oxygen from the metal and form carbon dioxide

What metals use electrolysis for extraction

Potassium, Sodium, Lithium, Calcium, Magnesium

Why is electrolysis used for the metals Potassium, Sodium, Lithium, Calcium, and Magnesium

Because metals are more reactive than carbon will not be reduced by it, so electrolysis is used instead

Why are the disadvantages of using electrolysis for extraction

Expensive

How can you tell how reactive a metal is

The more easily a metal loses its electrons and forms positive ions, the more reactive the metal is

What are the highly reactive metals in the reactivity series, & how do they react with water and acid?

Potassium, Sodium, Lithium: react vigorously with water and acid, producing hydrogen gas

Which metals also react with water and acid, and describe the reaction?

Magnesium and Calcium react less vigorously with water and acid than the metals higher up in the series

What metal in the series does not react with either water or acid?

Copper

How does zinc and Iron react with water and acid

Does not react with liquid water but reacts with water in the form of steam, and reacts very slowly with acid in comparison to metals above

What products are formed when metals react with metals and water?

Metal Hydroxides + Hydrogen gas

What products are formed when metals react with oxygen?

Metal Oxides

What products are formed when metals react with acids?

Metal salt + Hydrogen gas

What type of salt is formed in a reaction with hydrochloric acid?

Chloride

What type of salt is formed in a reaction with Sulphuric acid?

Sulphate

What type of salt is formed in a reaction with Nitric acid?

Nitrate