C8-C14 Flashcards
(18 cards)
What are the four main factors affecting the rate of a chemical reaction?
Temperature, concentration (or pressure), surface area of reactants, and use of a catalyst.
How does increasing temperature affect rate of reaction?
Particles move faster and collide more often with more energy, increasing successful collisions.
Required Practical: Describe how to investigate the rate of reaction using sodium thiosulfate and hydrochloric acid.
Mix sodium thiosulfate with HCl in a conical flask on top of a cross mark. Time how long it takes for the cross to disappear as sulfur precipitates, varying concentration to study rate.
What is crude oil made of?
A mixture of hydrocarbons, mostly alkanes.
Explain the process of fractional distillation of crude oil. (6 marks)
- Crude oil is heated and vaporised. 2. Vapours enter a fractionating column. 3. Column is hotter at the bottom and cooler at the top. 4. Hydrocarbons condense at different levels based on boiling points. 5. Fractions collected: gases, petrol, kerosene, diesel, etc. 6. Used for fuels and feedstocks.
What are the products when alkenes react with bromine water?
Dibromoalkanes are formed; bromine water decolorises from orange to colourless.
Describe addition polymerisation.
Unsaturated monomers (alkenes) join together to form a long chain polymer with no other products.
What is a condensation polymer and how does it differ from addition polymer?
Formed when monomers join and lose small molecules (e.g., water). Unlike addition polymers, they come from monomers with two functional groups.
Give an example of a natural polymer.
DNA, proteins, starch, cellulose.
What is a pure substance in chemistry?
A single element or compound with a fixed boiling/melting point.
Required Practical: Describe how to separate substances using paper chromatography.
Draw baseline on chromatography paper, place spots of ink, dip in solvent without touching the baseline. Solvent carries dyes up paper at different rates. Measure Rf values.
What is the test for hydrogen gas?
Insert lit splint – a ‘pop’ sound confirms hydrogen.
What is the flame test result for lithium?
Crimson red flame.
Describe the changes in Earth’s atmosphere over time.
Early atmosphere: mostly CO2, some N2. Over time, photosynthesis increased O2, CO2 reduced as it dissolved in oceans or formed sedimentary rocks and fossil fuels.
What human activities increase greenhouse gases?
Burning fossil fuels (CO2), farming (methane), deforestation (reduces CO2 absorption).
What is potable water and how is it produced?
Water safe to drink, not pure. Produced by filtering to remove solids, sterilising to kill microbes (e.g., with chlorine or UV light).
Required Practical: How do you purify salty water?
- Distillation: Heat salty water, collect distilled steam. 2. Test for purity by measuring boiling point (100°C = pure).
What is an LCA and why is it important in product design? (6 marks)
LCA assesses environmental impact of a product over its lifetime: extraction of raw materials, manufacture, use, and disposal. Helps companies reduce carbon footprint and waste.
