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C2 rates energy

Edexcel C2 rates of reaction And energy

QuestionAnswer
name 4 factors that can speed up a reaction Hotter solution, More concentrated, Smaller bits, Catalyst (to merely say "heat" is not enough... read the question)
explain why a reaction goes faster when a solution is more concentrated there are more particles IN THE SAME VOLUME, so there will be more FREQUENT collisions
explain why a reaction goes faster when a solution is hotter Particles move FASTER, so the collisions have more energy, the collisions are more FREQUENT and more SUCCESSFUL
explain why a reaction goes faster when bits are smaller there is a larger surface area exposed, so more particles can react so there are more collisions (for the same period of time)
what is a catalyst? a chemical that speeds up the reaction without getting used up
explain how a catalyst speeds up a reaction it lowers the activation energy and provides an alternative pathway
what is the activation energy the minimum of energy required for the particles to collide and bonds to break
An excess of Magnesium is reacted with a dilute solution of Acid. 40cm3 of Hydrogen is collected. The experiment is repeated at a hotter temperature. How much gas will be collected? More/less/same as (ie40cm3) The same as: 40cm3; because you have the same amounts at the start in both experiments; so you collect the same at the end!
A student plots volume of gas collected against time for a given reaction. He repeats the experiment at a hotter temperature. Would you expect the line at the start to be steeper/not as steep/same gradient? As the reaction is faster, the line will be steeper (more volume collected for the same time)
How do manufacturers of cars ensure that the catalytic converters convert the maximum possible of harmful gases into Carbon Dioxide and Water? Increasing surface area (honeycomb structure); high temperature
In the catalytic converter, what are the harmful gases that need to be converted before coming out of the exhaust? Carbon monoxide and Unburnt Hydrocarbons
Is bond breaking process endo or exothermic? Endo ENTBB
Is bond making process endo or exothermic? Exo EGOMB
Explain why some reactions are exothermic Because there is more energy-given-out-when-new-bonds-are-formed than taken-in-when-bonds-are-broken ENTBB < EGOMB
Explain why some reactions are endothermic? Because there is more energy-taken-in-when-bonds-are-broken than energy-given-out-when-new-bonds-are-formed than ENTBB > EGOMB
Name some chemical reactions that are endothermic Photosynthesis, dissolving ammonium nitrate
What is the trick to remember for questions on energy compare ENTBB to EGOMB
A student plots volume of gas collected against time for a given reaction. He repeats the experiment at a hotter temperature. Would you expect the line at the end to be higher/lower or at the same height as the first experiment? same height because the same AMOUNT of chemicals was taken for both experiment
Describe the energy diagram for an exothermic reaction (no need to discuss bond making or bond breaking) The levels of the reactants (on the left) are higher than the levels of the products (on the right); the arrow joining the two levels is going down
Describe the energy diagram for an endothermic reaction (no need to discuss bond making or bond breaking) The levels of the reactants (on the left) are lower than the levels of the products (on the right); the arrow joining the two levels is going down
Describe the energy diagram for an exothermic reaction (including bond making or bond breaking) The levels of the reactants (on the left) are higher than the levels of the products (on the right); the arrow joining the two levels is going down; draw the "HUMP" to join the two levels
Describe the energy diagram for an endothermic reaction (including bond making or bond breaking) The levels of the reactants (on the left) are lower than the levels of the products (on the right); the arrow joining the two levels is going down; draw the "HUMP" to join the two levels
Predict what would happen to the rate of reaction if in the second experiment, you took double the volume of the same concentration, at the same temperature Nothing! Volume does not affect the rate of reaction!
Created by: UrsulineChem