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GCSE2 rate reaction

AQA GCSE chapter 08 (part 1) rate of reaction

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 FREQUENT 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
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
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!
An excess of Magnesium is reacted with a dilute solution of Acid. 40cm3 of Hydrogen is collected. The experiment is repeated with a MORE CONCENTRATED acid. How much gas will be collected? More/less/same as (ie40cm3) More than 40cm3; because there is more particles FOR THE SAME VOLUME in the concentrated acid so more gas particles will be collected
An excess of Magnesium is reacted with a dilute solution of Acid. 40cm3 of Hydrogen is collected. The experiment is repeated with a MORE CONCENTRATED acid.Would you expect the line at the start to be steeper/not as steep/same gradient? More concentrated=faster; As the reaction is faster, the line will be steeper (more volume collected for the same time)
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? Hotter=faster; As the reaction is faster, the line will be steeper (more volume collected for the same time)
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
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!
A students places Marble chippings in acid and observe the volume of gas collected. DESCRIBE the shape of the graph (volume on y-axis and time on x-axis) Steep line at the start, the line is not so steep and at some stage the line goes HORIZONTAL (do not say flat)
A students places Marble chippings in acid and observe the volume of gas collected. EXPLAIN the graph (volume on y-axis and time on x-axis) will level out and have an horizontal line at the end Steep line at the start because there are LOTS of particles in the same volume, as the reaction progresses there are less particles so slower reaction; eventually there are no particles, no gas is produced and the line goes HORIZONTAL
How do you work out the rate of reaction in the thio experiment where you observe how long it takes for the cross to disappear? rate=1/time
On a graph volume of gas vs time, how would you work out the rate of reaction at time=0seconds? Draw the tangent to the curve; draw a LONG tangent; then work out the gradient of the tangent; the gradient is the rate
How do you work out the gradient of a line? gradient=rise over run; take points that are as far as possible
Created by: ursulinechem2