aqa gcse science Flashcards
What is the general formula of an alkane?
CₙH₂ₙ₊₂
What are the four main factors affecting rates of reaction?
- Temperature
- Surface area
- Concentration or pressure
- Presence of a catalyst
What is Activation Energy?
The smallest amount of energy needed by particles to react
How can the rate of reaction be measured using mass?
By measuring the rate at which mass is lost if gas is produced
What happens to the rate of reaction when temperature increases?
The rate of reaction increases because particles move faster and collide more often
Fill in the blank: The __________ is the measure of how steep a line is on a reaction graph.
gradient
True or False: Increasing pressure in gases decreases the likelihood of particle collisions.
False
What is a reversible reaction?
A reaction where the products can turn back into the reactants
What effect does increasing temperature have on a reversible reaction?
It favours the endothermic reaction
What are hydrocarbons?
Compounds made of just hydrogen and carbon
What is fractional distillation?
The separation of crude oil into different fractions in a fractionating column
What are the products of complete combustion of hydrocarbon fuels?
- Carbon dioxide
- Water
What is cracking in organic chemistry?
The process of breaking down large hydrocarbons into shorter chains
What indicates the presence of alkenes in a reaction?
They react with orange bromine water to produce a colourless liquid
What defines a pure substance?
A substance that contains only one element or compound
Fill in the blank: Rf values in chromatography can be measured and matched against __________ to identify specific substances.
databases
What is the main component of the Earth’s atmosphere today?
Approximately 80% nitrogen and 20% oxygen
What are the potential risks of global climate change?
- Rising sea levels
- Threats to ecosystems
- Different patterns of food production
What is the main greenhouse gas produced when hydrocarbon fuels are burnt?
Carbon dioxide
What is the role of catalysts in reactions?
They increase the rate of reaction by lowering the activation energy
What process is used to treat wastewater?
- Screening
- Sedimentation
- Aerobic biological treatment
What is the purpose of Life Cycle Assessments (LCAs)?
To assess the environmental impact of products, processes, or services
True or False: Recycling metals saves energy and reduces pollution from mining.
True
What is the main component of the Earth’s early atmosphere?
Mainly CO₂, with possibly water vapour, methane, and ammonia
What is the effect of increased greenhouse gases in the atmosphere?
It is likely to increase average global temperatures
What is the purpose of adding chlorine to drinking water?
To reduce microbes and sterilize the water
How can copper be extracted from copper-rich ores?
- Smelting
- Reaction with sulfuric acid
What happens during incomplete combustion of hydrocarbons?
Carbon monoxide is produced as a poisonous gas
Fill in the blank: The amount of energy, water, and resource consumption are analyzed in __________.
Life Cycle Assessments
