Chemistry full set

What is the rate of a chemical reaction?

How fast reactants are turned into products.

How can you measure the rate of reaction?

By measuring the amount of product formed or reactant used over time.

Name two factors that affect rate of reaction.

Temperature and concentration.

How does temperature affect rate?

Increases kinetic energy, leading to more frequent successful collisions.

How does concentration affect rate?

More particles in the same space = more frequent collisions.

How does surface area affect rate?

More surface area = more particles exposed = faster rate.

What does a catalyst do?

Speeds up a reaction without being used up.

How do catalysts work?

By lowering the activation energy.

What is collision theory?

Particles must collide with sufficient energy and correct orientation to react.

What is activation energy?

The minimum energy required for a reaction to occur.

What does a steeper line on a rate graph show?

A faster reaction.

What is the equation for mean rate of reaction?

Rate = quantity of reactant used or product formed ÷ time.

How is equilibrium defined?

When the forward and reverse reactions occur at the same rate in a closed system.

What happens to the concentration of reactants/products at equilibrium?

It stays constant (but not necessarily equal).

What is Le Chatelier's Principle?

A system at equilibrium will adjust to counteract changes made to it.

What effect does increasing pressure have on a gaseous equilibrium?

Shifts equilibrium to side with fewer gas molecules.

What effect does increasing temperature have on equilibrium?

Shifts it in the endothermic direction.

Give one example of a reversible reaction.

Ammonium chloride ⇌ ammonia + hydrogen chloride.

What is a hydrocarbon?

A compound made of hydrogen and carbon only.

What is crude oil?

A finite mixture of hydrocarbons formed from ancient biomass.

What are alkanes?

Saturated hydrocarbons with single bonds.

What is the general formula for alkanes?

CₙH₂ₙ₊₂

Name the first four alkanes.

Methane, ethane, propane, butane.

What is fractional distillation?

Separating a mixture (like crude oil) into fractions based on boiling points.

What are the fractions of crude oil used for?

Fuels and feedstock for the petrochemical industry.

What is cracking?

Breaking large hydrocarbons into smaller, more useful ones.

Why do we crack hydrocarbons?

To meet demand for shorter chain alkanes and produce alkenes.

What are alkenes?

Unsaturated hydrocarbons with at least one C=C double bond.

What is the test for alkenes?

They decolourise orange bromine water.

What are the products of complete combustion of hydrocarbons?

Carbon dioxide and water.

What are the products of incomplete combustion?

Carbon monoxide, carbon (soot), and water.

What is the formula of ethanol?

C₂H₅OH

What is fermentation?

Using yeast to convert sugars into ethanol and carbon dioxide.

What is the functional group in alcohols?

–OH

What is the functional group in carboxylic acids?

–COOH

What happens when carboxylic acids react with carbonates?

They form a salt, water, and carbon dioxide.

What is a polymer?

A large molecule made by joining many monomers.

What is addition polymerisation?

When alkenes join to form polymers, with no other products.

What is condensation polymerisation?

Joining monomers with two functional groups, producing a polymer and a small molecule (e.g., water).

What are natural polymers?

Polymers found in nature, e.g., proteins, DNA, starch.

What is the test for hydrogen gas?

It makes a squeaky pop with a lit splint.

What is the test for oxygen?

It relights a glowing splint.

What is the test for carbon dioxide?

It turns limewater cloudy.

What is the test for chlorine?

It bleaches damp blue litmus paper white.

What is a pure substance (in chemistry)?

A substance made of only one type of element or compound.

How can you tell if a substance is pure?

It has a sharp melting or boiling point.

What is a formulation?

A useful mixture with a precise purpose, made by mixing specific amounts.

Give an example of a formulation.

Paint, fuel, cleaning products, or medicines.

What is chromatography used for?

To separate mixtures and identify substances.

What is the stationary phase in paper chromatography?

The paper.

What is the mobile phase in paper chromatography?

The solvent (e.g., water or ethanol).

How do you calculate Rf value?

Rf = distance moved by spot ÷ distance moved by solvent.

What was the Earth's early atmosphere mostly made of?

Carbon dioxide with little or no oxygen.

How did oxygen levels in the atmosphere increase?

Algae and plants photosynthesised.

What caused CO₂ levels to decrease?

Dissolved in oceans and formed sedimentary rocks.

What is the greenhouse effect?

Trapping of infrared radiation by gases in the atmosphere.

Name two greenhouse gases.

Carbon dioxide and methane.

Give one human activity that increases methane.

Farming cattle or landfill.

What is global warming?

A rise in the Earth's average surface temperature.

Give one consequence of global warming.

Melting ice caps, sea level rise, extreme weather.

What is a carbon footprint?

The total amount of CO₂ and other greenhouse gases emitted over the life cycle of something.

Give one way to reduce carbon footprint.

Using renewable energy or increasing energy efficiency.

Name a pollutant from burning fossil fuels.

Carbon monoxide, sulfur dioxide, nitrogen oxides, particulates.

Why is carbon monoxide dangerous?

It binds with haemoglobin, preventing oxygen transport.

What causes acid rain?

Sulfur dioxide and nitrogen oxides dissolving in rainwater.

What are the effects of acid rain?

Damages buildings, kills plants and aquatic life.

What is potable water?

Water that is safe to drink but not chemically pure.

What is desalination?

Removing salt from seawater to produce potable water.

Name two methods of desalination.

Distillation and reverse osmosis.

What is wastewater?

Water that has been used and contaminated (e.g., sewage).

Name three steps in sewage treatment.

Screening, sedimentation, and aeration.

What is life cycle assessment (LCA)?

A method to assess environmental impact of a product over its whole life.

Why are LCAs sometimes unreliable?

They involve value judgments and assumptions.

What is a finite resource?

A resource that will eventually run out (e.g., crude oil).

What is a renewable resource?

A resource that can be replaced naturally (e.g., biofuels).

What is corrosion?

The destruction of materials by chemical reactions with the environment.

What is rusting?

The corrosion of iron in the presence of oxygen and water.

How can rusting be prevented?

Painting, oiling, plastic coating, or galvanising.

What is galvanising?

Coating iron with zinc to prevent rusting.

What is sacrificial protection?

Using a more reactive metal to protect a less reactive one.

What is an alloy?

A mixture of metals (or a metal and another element) to improve properties.

Give an example of an alloy.

Brass (copper and zinc), steel (iron and carbon).

Why are alloys harder than pure metals?

Different-sized atoms disrupt layers, preventing them sliding.

What are ceramics?

Brittle, heat-resistant non-metal solids like clay or glass.

What is borosilicate glass?

A type of glass with a higher melting point than soda-lime glass.

What is a composite material?

A material made from two or more substances with improved properties.

Give an example of a composite.

Fibreglass, carbon fibre, concrete.

What is the Haber process used for?

Making ammonia from nitrogen and hydrogen.

What are the conditions for the Haber process?

450°C, 200 atm, iron catalyst.

Why is ammonia important?

It’s used to make fertilisers like ammonium nitrate.

What is NPK fertiliser?

A fertiliser containing compounds of nitrogen, phosphorus, and potassium.

What raw material is used to get nitrogen in fertiliser?

Ammonia from the Haber process.

How is phosphate rock treated to make fertiliser?

Reacted with acid to produce soluble salts.

How are potassium salts used in fertilisers?

They are mined and used directly.

What is the atom economy?

Atom economy = (Mr of desired product ÷ total Mr of all products) × 100

Why is high atom economy good?

It reduces waste and uses resources efficiently.

What is percentage yield?

(Actual yield ÷ theoretical yield) × 100

What does a low yield mean?

Some product was lost or the reaction was incomplete.

What are the units for concentration?

grams per dm³ or mol per dm³.

What is the formula for concentration?

Concentration = mass ÷ volume