Reactive Chemistry

What are some indications of a chemical change?

Change in colour, vapour produced, gas produced causing bubbles, change from solution to suspension, temperature changing, flames

Word equation for metal/acid

metal + acid → salt + hydrogen gas

How can you tell if a metal/acid reaction has taken place?

You can test for hydrogen gas produced using the pop test

What is an example of a metal/acid reaction

Mg +2HCl → MgCl2 + H2

Define ‘acids’

Substances that dissolve in water to produce H+ ions

Define ‘bases’

Substances that dissolve in water to produce OH- ions

Word equation for acid/base reaction

Acid + base → salt + water

What is an example of an acid/base reaction?

HCl + NaOH → NaCl + H2O

Is neutralisation an endothermic or exothermic reaction?

Exothermic (reaction mixture warms up)

What are the subset reactions under acid/base reactions?

Acid/carbonate reactions, metal oxide/acid reactions, metal hydroxide/acid reactions

Are carbonates mostly soluble or insoluble?

Mostly insoluble

Word equation for acid/carbonate reaction

Metal carbonate + acid → a salt + water + carbon dioxide

What is an example of an acid/carbonate reaction?

CH3COOH + NaHCO3 → CH3COONa + CO2 + H2O (reaction of baking soda and vinegar)

Word equation for metal oxide/acid reaction

Metal oxide + acid → a salt + water

What is an example of a metal oxide/acid reaction?

CuO + 2HCl → CuCl2 + H2O

Word equation for metal hydroxide/acid reaction

Metal hydroxide + acid → a salt + water

What is an example of metal hydroxide/acid reaction?

2NaOH + H2SO4 → Na2SO4 + 2H2O

Define ‘combustion’

Burning, where a substance combines with oxygen

Are combustions exothermic or endothermic?

They are all exothermic

What are the 3 different types of combustion reactions?

Hydrocarbon combustions, metal combustions, and corrosion reactions (very slow)

Word equation for hydrocarbon combustion reaction

hydrocarbon + oxygen → carbon dioxide + water

What is an example of a hydrocarbon combustion reaction?

CH4 + 2O2 → CO2 + 2H2O

Word equation for metal combustion reaction

metal + oxygen → metal oxide

What is an example of a metal combustion reaction?

2Mg + O2 → 2MgO

Word equation for corrosion reaction

Metal + oxygen → metal oxide

What is an example of a corrosion reaction?

4Fe + 3O2 → 2Fe2O3 (rusting of iron in air)

What occurs during a precipitation reaction?

Two soluble ionic compounds are mixed together in water and produce two new ionic compounds. If one of those new ionic compounds is insoluble, it appears as a solid precipitate

What is an example of a precipitation reaction?

Pb(NO3)2 + 2NaI → PbI + 2NaNO3

What occurs during a decomposition reaction?

A single substance breaks down into simpler compounds or elements

What is an example of a decomposition reaction?

CuCO3 → CuO + CO2

What is a thermal decomposition reaction?

An endothermic reaction which gains energy from its surroundings

What occurs during a synthesis reaction?

Two or more reactants combine to create a more complex substance

What is an example of a synthesis reaction?

6CO2 + 6H2O → C6H12O6 + 6O2 (photosynthesis)

What is the ‘SNAAP’ rule?

An acronym to remember ions that, if present in a salt, make that salt soluble

What does SNAAP stand for?

S - sodium (Na+)

N - nitrate (NO3 -)

A - ammonium (NH4+)

A - acetate (CH3COO-)

P - potassium (K+)

What are ‘spectator ions’?

Ions that do not participate in the reaction and are thus unchanged by the reaction

What is a ‘net ionic equation’?

An equation which omits the spectator ions

What metals can be found in their pure, metallic form in nature?

Silver and gold

Why are silver and gold found in nature in their pure metallic form but not other, more abundant metals such as aluminium or sodium?

Silver and gold are much less reactive than other metals, therefore do not react with other substances to form compounds as other metals do

What forms when metal reacts with oxygen?

Metal oxide

What happens when a metal is reacted with an aqueous solution of another metal?

The more reactive metal will displace a less active metal ion from the solution

What is an example of a metal + other metallic ion in solution reaction?

Cu + 2Ag(+) → Cu(2+) + 2Ag

What are some signs that a metal + other metallic ion in solution reaction has taken place?

* More active metal will dissolve
* Less active metal will appear at the bottom of tube/plate on the surface of the more active metal
* Solution may change colour
* Reaction vessel gets warm

What 3 different factors dictate the reactivity of a metal?

1. first ionisation energy
2. atomic radius
3. electronegativity

Describe how first ionisation energy dictates the reactivity of a metal

Metal activity increases as first ionisation energy decreases (with a few exceptions)

What is first ionisation energy?

The energy required to remove one mole of the most loosely held electrons from one mole of gaseous atoms to produce one mole of gaseous ions each with a charge of 1+

What are first ionisation energies measured in?

kJ mol- 1

What is first ionisation energy affected by?

* size of nucleus (no. of protons)
* distance between the electron and the nucleus
* number of electrons between valence electrons and the nucleus (shielding)

Describe how atomic radius dictates the reactivity of a metal

As you move down a group and the atomic radius increases, metal activity also increases

Describe how electronegativity dictates the reactivity of a metal

The less electronegative an atom is, the less energy it will take for it to give up its valence electrons

What makes a base/acid strong?

Its ability to dissociate completely