CHEM PAPER 2

• What things affect the rate of reaction?

  Temperature, concentration, pressure, surface area, presence of a catalyst.
• How does increasing the temperature increase the rate of reaction?

  1) particles move faster because there is more energy

  2) so there are more frequent successful collisions

  3) so the reaction happens faster
• How does increasing concentration or pressure increase the rate?

  1) there are more particles in a given volume

  2) so there are more frequent successful collisions

  3) increasing the rate of reaction
• How does increasing the surface area increase the rate of reaction?

  1) increases its surface area to volume ratio

  2) the particles have more area to work on

  3) so there will be more frequent successful collisions.
• How does a catalyst increase the rate of a reaction?

  It provides an alternative reaction pathway with a lower activation energy.
• What's the formula for rate of reaction?

  Reactant used OR product formed/ time
• Describe the practical for measuring rate of reaction using a liquid?

  1) Add dilute HCl to sodium thiosulfate.

  2) measure how long it takes for a cross underneath the beaker to disappear

  3) The solution will go cloudy.

  4) repeat with different solutions or different concentrations.
• Describe the practical for measuring rate of reaction using mass change?

  1) Add dilute HCl to a beaker on a scale and add magnesium.

  2) When hydrogen is given off as a product, it will escape and lower the mass.

  3) measure how quickly it takes for the mass to decrease, determining the rate.
• Describe the practical for measuring rate of reaction using volume of a gas given off?

  1) use gas syringe to measure the volume given off

  2) the more gas given off in a time period, the faster the reaction is.
• What are reversible reactions?


  Where the products of the reaction can themselves react to produce the original reactants
• What is an exothermic process?

  A process that releases heat to the surroundings
• What is an endothermic reaction?

  a reaction that takes in energy from its surroundings
• What is Le Chatelier's principle?

  When a reaction at equilibrium is changed, it will seek to counteract that change
• What happens when you increase the temperature in a reversible reaction?

  1) The equilibrium will move to the endothermic side to try and decrease the temp.

  2) There will be more products on the endothermic side and fewer on the exothermic side.
• What happens when you increase the pressure in a reversible reaction? (Only in gases)

  1) The equilibrium will move to the side with fewer molecules of gas.
• What happens when you increase the concentration in a reversible reaction?

  The system tries to decrease it by making more products
• What is equilibrium?


  Equilibrium is reached when the reactions occur at the same time/rate in a closed system.
• How is crude oil formed?

  Over millions of years from the fossilised remains of plankton
• Where is crude oil found?

  In the porous rocks in the Earth's crust
• Is crude oil renewable or non-renewable?

  Non-renewable
• What is crude oil made up of?

  Hydrocarbons
• What gives hydrocarbon molecules varying properties?

  They vary in size
• What happens to the properties of hydrocarbons as the molecules get larger?

  It gets more viscous, its boiling point gets higher, the less volatile it is, the less easily it ignites
• How are the components of crude oil separated?

  Fractional distillation
• Why does fractional distillation work?

  Different sized molecules of hydrocarbons have different boiling points
• What piece of equipment does fractional distillation take place in?

  Fractionating column
• What are the stages of fractional distillation?

  1) the crude oil is heated until it evaporates 2) the molecules move up the fractionating column which is hotter at the bottom 3) larger molecules condense at the hotter bottom of the column and are collected 4) the shorter molecules condense at the cooler top of the column and are collected
• What is an alkane?


  A hydrocarbon in which each carbon molecule makes 4 single bonds with other molecules
• Are alkanes saturated or unsaturated?

  Saturated
• What is the general formula for an alkane?

  CnH2n+2
• What is the name of an hydrocarbon with 1 carbon molecule?

  Meth(ane/ene)
• What is the name of an hydrocarbon with 2 carbon molecules?

  Eth(ane/ene)
• What is the name of an hydrocarbon with 3 carbon molecules?

  Prop(ane/ene)
• What is the name of an hydrocarbon with 4 carbon molecules?

  But(ane/ene)
• What is the name of an hydrocarbon with 5 carbon molecules?

  Prop(ane/ene)
• What happens during the combustion of hydrocarbons?

  Carbon and hydrogen are oxidised, energy is released, waste products are released into the atmosphere
• What happens in incomplete combustion?

  Carbon monoxide is produced which is poisonous. Soot is given off
• What is the effect of particulates?

  They cause global dimming by reducing the amount of sun that can reach the earth's surface, they cause damage to people's lungs
• How are nitrogen oxides produced from combustion?

  When high temperatures from combustion are reaches, nitrogen in the air reacts with oxygen
• What problems do nitrogen oxides cause?

  Cause respiratory problems, react with rainwater to form acid rain