C6 - rates
What happens to the rate of reaction when temperature increases?
Rate increases
State the general formula of the alkanes
CnH₂n+2
Define formulation
a mixture designed to be a useful product ✔
What are greenhouse gases? Give two examples.
Gases that trap heat
Carbon dioxide
water
methane
What is a finite resource?
Resource that will run out
Explain how concentration affects the rate of reaction
More particles in same volume
More frequent Collisions
More frequent successful collisions
higher rate
Methane ✔
Ethane ✔
Propane ✔
Butane ✔
Describe the test for hydrogen gas.
Place a lighted splint in the gas
How did carbon dioxide decrease in the early atmosphere?
Dissolved in oceans ✔
Formed carbonate rocks ✔
Taken in by plants (photosynthesis
What is potable water?
Water that is safe to drink
Explain how a catalyst affects the rate of reaction
A catalyst speeds up a reaction ✔
It is not used up ✔
Lowers activation energy
Complete the word equation for complete combustion of a hydrocarbon:
Hydrocarbon + oxygen → ______ + ______
Carbon dioxide ✔
Water ✔
What is the test for carbon dioxide gas?
Bubble gas through limewater ✔
Limewater turns cloudy/milky ✔
Name at least 4 atmospheric pollutants
Sulphur dioxide
Carbon dioxide
Nitrogen oxides
Soot
Carbon monoxide
Why is recycling important?
Reduces waste ✔
Saves raw materials ✔
Saves energy
A reaction produces 60 cm³ of gas in 30 seconds.
Calculate the rate of reaction (cm³/s).
Rate = volume ÷ time ✔
= 60 ÷ 30 ✔
= 2 cm³/s ✔
Describe how fractional distillation separates crude oil into different fractions.
Crude oil is heated until it evaporates ✔
Vapours enter the fractionating column ✔
Column is hot at bottom, cooler at top ✔
Different hydrocarbons have different boiling points ✔
They condense at different heights ✔
What is meant by a pure substance, and how can you tell if a substance is pure?
A pure substance contains only one element or compound ✔
No other substances mixed in ✔
Has a fixed/sharp melting point ✔
Has a fixed/sharp boiling point ✔
Explain how human activities increase carbon dioxide levels.
Burning fossil fuels ✔
Deforestation ✔
Releases CO₂ ✔
Describe how fresh water is treated.
Screen
Filter
Sterlise
Explain in detail why temperature affects the reaction rate, including collision theory and activation energy.
Temperature increases kinetic energy ✔
Particles move faster ✔
Collisions happen more often ✔
Collisions are more energetic ✔
More particles exceed activation energy ✔
So more successful collisions → faster rate ✔
How was crude oil formed?
Formed from remains of ancient plankton ✔
Buried under sediment ✔
Over millions of years ✔
High pressure and temperature ✔
A substance travels 3 cm on a chromatography paper.
The solvent front travels 6 cm.
Calculate the Rf value.
Rf = distance by substance ÷ distance by solvent
= 3 ÷ 6 ✔
= 0.5 ✔
Explain the greenhouse effect and how it leads to global warming.
Sun’s radiation enters Earth ✔
Earth emits infrared radiation ✔
Greenhouse gases absorb this ✔
Re-radiate heat back to Earth ✔
Leads to warming ✔
Enhanced effect → global warming ✔
Describe how waste water is treated.
Screen
Sedimentation
Anaerobic digestion ( sludge)
aerobic digestion (effluent)