RP3 Flashcards

1
Q

How can rate of reaction be measured?

A

● Initial rates method- i.e. the iodine clock reaction.
● A continuous monitoring method- i.e. measuring the volume of gas released in a reaction over time.

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2
Q

Why does rate of reaction increase with increasing temperature?

A

● As temperature increases, the kinetic energy of the molecules increases. This means more molecules have energy greater than the activation energy and can therefore react.
● Also as kinetic energy of molecules increases, their
velocities increase resulting in more frequent and
successful collisions.

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3
Q

How could you analyse the data?

A

● For a graph of the amount of sulfur against time, it would be a straight line at the beginning as the reaction has only just begun.
● Therefore the gradient of this straight section = rate of reaction.
● Compare the rate of reaction for each temperature. For further analysis, you could even plot a graph of rate of reaction against temperature.

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4
Q

How would you investigate how rate of reaction varies with temperature?
Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + SO2(g) + S(s)

A

Na2S2O3(aq) + 2HCl(aq) → 2NaCl(aq) + SO2(g) + S(s)
● This reaction produces a cloudy sulfur precipitate.
● To measure rate, time how long it takes for a cross
underneath the beaker to disappear, using a stopwatch (as more sulfur is produced, it will prevent you from seeing the cross).
● Repeat this at 5+ different temperatures and compare times taken.

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5
Q

What are some issues with this method?

A

● The disappeared cross is judged by eye and can therefore be unreliable.
● There may be a delayed reaction time with the stopwatch.
● At low temperatures the reaction may be too slow.
● There may not be enough precipitate for the cross
to disappear.

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6
Q

In an experiment investigating the effect of temperature on rate of reaction, what variables will you control?

A

● Concentrations of reactants and products.
● Volumes of reactants and products.
● Use the same beaker and cross underneath.
● Use the same person to decide when the
cross has disappeared.

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6
Q

What is a control variable?

A

A variable that is kept constant throughout the experiment.

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7
Q

How can we keep a substance at a constant temperature?

A

Using a water bath keeps the temperature constant. For this experiment you can set up water baths of different temperatures to see how it affects the rate of reaction.

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