Reaction Rates
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Define reaction rate
number of moles of product formed per second. or number of moles of reactant used per second
What is the unit for reaction rate
mol / s
What are the 4 methods for reaction rates
1) mass change 2) volume of gas 3) solid disappearing 4) color change
What is the reaction rate represented by on a graph?
the gradient
Define tangent
straight line that has the same gradient as 1 point on a curve
What is one way mass change can be measured? What would you measure?
by measuring the volume of gas made / used up
Why does the mass decrease when measuring mass change in a reaction between metal carbonate and acid?
because gas is produced, and as it goes out of the top of the conical flask and therefore the mass left in the flask is less than what is started at
Why shouldn’t you measure the initial volume of gas produced when measuring volume of gas?
because no gas is produced initially
What does a graph of measuring the mass change in a reaction with a metal carbonate and an acid look like?
add photo at home
What does a graph of measuring the volume of gas in a reaction with a metal and an acid look like? and tangent
add photo at home and tangent
What would you measure in a reaction of solid disappearing?
time until solid disappears
What are the problems with using solid disappearing as a rate of reaction?
• can only calculate average rate • no graph
What would you measure in a reaction of color change?
time until color change is observed
What are the problems with using color change as a rate of reaction?
• no graph • can only calculate average rate • subjective
Give an example of a color change reaction
iron (gray) + copper sulfate (blue) → iron (II) sulfate (green) + copper (orange)
What apparatus is needed when measuring volume of gas?
• gas syringe
Describe the ‘flow’ of a rate of reaction from beginning to end
the rate always decreases from beginning to end
Why does the rate of reaction decrease?
because the rate of collisions decreases
What happens when when reactants are used up during a reaction?
fewer particles are available
What happens at the end of a reaction?
there are no more reactants available therefore no collisions can occur
What do particles have to do in order for a reaction to happen?
they have to collide
What 2 properties are needed for particles to be able to collide?
1) sufficient energy 2) correct orientation
What is energy used for in a reaction?
to break the bonds of the reactants