Chapter 5: Chemical Changes

What does reactivity mean?

how vigorously a substance chemically reacts

How can metals be ordered by their reactivity?

by comparing their ractions with water, acid or oxygen.

What name is given to a list of metals ordered by ther reactivity?

reactivity series

In terms of electrons, what makes some metals more reactive than others?

they lose their outer shell electron(s) more easily

Why are gold and silver found naturally as elements in the Earth’s crust?

they are very unreactive

What is an ore?

rock containing enough of a metal compound to be economically worth extracting

How are metals less reactive than carbon extracted from their ores?

reduction with carbon

In terms of oxygen, what is oxidisation?

addition of oxygen

In terms of oxygen, what is reduction?

removal of oxygen

Why can metals like potassium and aluminium not be extracted by reduction with carbon?

they are more reactive than carbon

How are metals more reactive than carbon extracted from their ores?

electrolysis

What is a displacement reaction?

a more reactive substance takes the place of a less reactive substance in a compound

What is an ionic equation?

Equation which gives some substances as ions and has spectator ions removed

What type of sunstance is given as ions in an ionic equation?

ionic comopounds in solution (or liquid)

What is a spectator ion?

ion that is uncharged in a reaction

What is a half equation?

equation that shows wether a substance is losing or gaining electrons

In terms of electrons, what is oxidisation?

loss of electrons

In terms of electrons, what is reduction?

gain of electrons

In terms of pH, what is an acid?

a solution with a pH of less than 7

In terms of pH, what is a neutral solution?

a solution with a pH of 7

In terms of H+ ions, what is an acid?

a substance that releases H+ ions when dissolved in water

How is the amount of H+ ions in a solution related to its pH?

the more H+ ions, the lower the pH

What are the names and formulae of three main acids?

hydrochloric acid, HCl; sulfuric acid, H2SO4; nitric acid, HNO3

How do you measure the pH of a substance?

universal indicator or pH probe

What is a strong acid?

an acid where the molecules or ions completely ionise in water

What is a weak acid?

an acid where the molecules or ions partially ionise in water

What is a salt?

compound formed when a metal ion takes the place of a hydrogen ion in an acid

Which type of salts do sulfuric acid, hydrochloric acid, and nitric acid form?

sulfates, chlorides, nitrates

What are the products of a reaction between a metal and an acid?

salt + hydrogen

What are the products of a reaction between a metal hydroxide and an acid?

salt + water

What are the products of a reaction between a metal oxide and an acid?

salt + water

What are the products of a reaction between a metal carbonate and an acid?

salt + water + carbon dioxide

What is a base?

substance that reacts with acids in neutralisation reactions

What is an alkali?

substance that dissolves in water to form a solution above pH 7

What is a neutralisation reaction?

a reaction between an acid and a base to produce water

What is the ionic equation for a reaction between an acid and an alkali?

H+(aq) + OH−(aq) ➞ H2O(l)

How can you obtain a solid salt from a solution?

crystallisation

When an acid reacts with a metal, which species is oxidised?

the metal

When ann acid reacts with a metal, which species is reduced?

hydrogen

What are the four state symbols and what do they stand for?

(s) solid, (l) liquid, (g) gas, (aq) aqueous or dissolved in water