chemistry Flashcards
what factors will you investigate if you were investigating fuels
- how much energy they produce
- what pollutants they produce
- how a fuel is chosen for specific purposes, heating rooms and cooking
what type of reaction is the combustion of fuels
exothermic, energy is released
what is the equation for combustion is fuels
fuel + oxygen = (arrow) carbon dioxide + water (+ heat energy)
what is the rule when balancing combustion equations
1C = 1CO2 2H = 1H2O
what does it mean in combustion when there is a longer carbon chain
the more energy is released during combustion
what are factors to consider when choosing a fuel
- how easy it is to ignite
- how easy it is to store
- how easy it is to transport
- how much/type of pollution it produces
what is flammability
- fuels are flammable, this means that they easily catch fire
- it is a hazard as there is a risk of fire and burns when working with fuels
what is toxicity
many fuels contain impurities that are toxic, fossil fuels normally contain benzene which is toxic
they produce combustion of impurities such as sulfur impurities being released as sulfur dioxide
what is sulfur dioxide
reacts with moisture in the air to produce acid rain
what is wrong with acid rain
- erodes limestone buildings and statues
- acidifies lakes and rivers
- kills acidifies lakes and rivers
why does combustion happen
because there is plenty oxygen present
what is the type of combustion that happens when there is limited oxygen
incomplete combustion
what does incomplete combustion produce
carbon monoxide and soot
what is the formula for incomplete combustion
fuel + oxygen (arrow) carbon monoxide + water ( + heat energy)
what is bad about carbon monoxide
a poisonous gas and can cause headaches, dizziness, nausea and death
what is wrong with soot
causes respiratory problems
what is energy measured in
Joules
what is specific heat capacity
4.2 joules of energy to raise the temperature of 1 g of water by 1 degree
how many kelvins equal 1 degree
274k = 1 degree
what is the formula for specific heat capacity
heat energy (j) = mass of water (g) X specific heat capacity of water (4.2 j) X temperature rise of water
how do you calculate the energy released of a fuel (heat of combustion)
heat of combustion (kJ mol) = heat energy supplied to water (kJ) x relative molecular mass of fuel/ mass of fuel burnt (g)
how do you convert kilojoule to joules
1 kJ = 1000 J
how do you convert kilometre to meter
1 km= 1000 m
how do you convert kilogram to gram
1 kg = 1000g
