Effect of temperature on reaction rate Flashcards Preview

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Flashcards in Effect of temperature on reaction rate Deck (14):
1

Identify the insoluble solid and colourless gas present in the reaction between sodium thiosulfate and dilute hcl

Insoluble solid : sulfur
Colourless gas : sulphur dioxide

2

Outline the experimental procedures you would follow in order to show the effect of temperature on reaction rate

Place a conical flask on a piece of paper marked with an X
Place fixed volume of a given concentration of thiosulfate in the flask
Place in a water bath to keep temperature constant
Add fixed volume of HCL to the flask and note the time taken for sulfur to obscure x, swirl conical flask, reaction is finished
Rate of reaction for concentration is inversely promotional to the time taken
Repeat the experiment with different temperatures [water bath]

3

Give two reasons why the rate of reaction between sodium thiosulphate solution and dilute hydrochloric acid increases with temperature

Increased temperature
-inc kinetic energy of particles which results in a greater number of collisions and increase in number of successful collisions and therefore an increased rate of reaction
-inc average kinetic energy of molecules which results in more molecules reaching required activation energy for the reaction which results in increase rate of reaction

4

Describe and explain the change observed in the conical flask during the reaction

Sulfur precipitates to yellow smokey appearance

5

Explain how the change in the flask was used to obtain the reaction times

X under conical flask obscured - reaction finished

6

Describe the relationship of temperature vs 1/t

as temp increases, the number of colliding particles. At a point, it will reach threshold level of activation energy and therefore resulting in more effective collisions and explains the steepness

7

What would the effect on reaction times if the experiment were repeated using 0.025M of sodium thiosulfate rather than 0.05M

-find relationship
twice as slow
Why - Rate is directly proportional

8

What is the variable in this experiment?

Temperature

9

Why is a dilute solution of sodium thiosulfate used in this experiment?

So that measured times will not be too short at higher temperatures (since r.or increases at higher temperature and if a concentrated solution were used, the reaction would proceed too fast to get a result)

10

Why is the temperature taken after the HCl is added?

Some cooling may have occured on addition of the HCl

11

Why is a stop-clock used in this experiment?

To accurately measure the time taken to obscure the cross

12

The graph for temperature versus rate is a curve, unlike the linear graph for concentration versus rate. Why is this so?

Rate of reaction is not directly proportional to the temperature

13

Give two everyday examples of temperature affecting the rate of reaction

-Food being stored in a fridge. The cold temperatures slows down the rate of decomposition of the food
-Catalytic converters in a car work most efficiently when heated as the rates of various reactions in catalytic converted are increased at higher temperatures

14

Name the gas given off when sodium thiosulfate reacts with HCl in this experiment and describe the smell

Sulfur dioxide - irritating and strong smell