Effects Of Temperature On The Rate Of Reaction

EFFECTS OF TEMPERATURE ON THE RATE OF REACTION Teacher’s Guide/ Chemistry Form 5 / Spreadsheet SCIENTIFITC CONCEPT Temperature is one of the effects that influence on the rates of reaction. By increasing the temperature, the rate of a reaction proportionally increases until it reach the limits where another factors might disturb the reaction from more increases. While the time taken for the reaction is shorter at a higher temperature. Inversely, the rate of reaction is going down as the temperature is decreases and the time taken for the reaction to occur becomes longer. EXPERIMENTS Temperature (0C) Time (s) 1/ time (s-1)

1 30 52 0.019

2 40 27 0.037

3 50 16 0.06

4 55 12 0.08

5 60 10 0.10

THE UNIQUE FEATURE OF THIS ACTIVITY •

The data can be manipulated easily, for example the time taken for ‘X’ to invisible during the experiment, the 1/t can be calculated.

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Data displayed in a systematic manner, save time in drawing graphs, show relationship of different concentration of reactant against time.

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Students will discover that a spreadsheet can be used to process data.

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Allow the students to do more important things such as analyzing the data or the graph.

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ENGAGE

(A)

(B)

Dissolving the sugar with hot water

Dissolving the sugar with water at room temperature

From the figures above; a) In which condition the sugar will dissolve first? b) Explain you answer in a).

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EMPOWER 1. Materials

Thermometer

Bunsen burner

Conical flask

Stopwatch

Sodium thiosulphate

White papers 3 marked ‘X”

Tripod stand

Measuring cylinder

Sulphuric acid

2. Students need to plan an experiment to determine the effect of temperature on the rate of reaction. 3. Students have to construct a hypothesis for this experiment. 4. Students should know the effect of temperature on the rate of reaction. 5. Help student to determine the variables involved. 6. You may give these instruction to start the activity:  Open a spreadsheet file  Name the file as “effect of temperature on the rate of reaction”  Measure 50cm3 of 0.2 mol dm-3 sodium thiosulphate solution and pour it into a

conical flask  Place the conical flask on top of a piece of white paper marked ‘X’  Measure 5cm3 of 1.0 mol dm-3 sulphuric acid and pour the acid quickly and

carefully into the conical flask. At the time start the stopwatch.  Swirl the mixture in the conical flask.  Observe the ‘X’ mark vertically from the top of the conical flask through the solution.  Stop the stopwatch once the ‘X’ mark disappears from view.  Record the time in the row B of your spreadsheet.  Repeat steps using 50cm3 of 0.2 mol dm-3 sodium thiosulphate at 400C, 500C, 550C

and 600C by heating the solution before adding the 5cm3of 1.0 mol dm-3 sulphuric acid.

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RESULTS EXPERIMENTS Temperature (0C) Time (s) 1/ time (s-1)

1 30 52 0.019

2 40 27 0.037

3 50 16 0.06

Graph 1: Temperature (0C) versus Time (s)

Graph 2: Temperature (0C) versus 1/Time (s-1)

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4 55 12 0.08

5 60 10 0.10

QUESTIONS 1. Consider the plotted graph (Graph 2), what can be said about the effect of the temperature

on the rate of reaction? 2. What if more concentrated of sulphuric acid is used in the experiment? What is the

effect? 3. Why the result obtained from the experiment vary from the actual result?

ANSWERS 1. From the Graph 2, show that temperature is proportional to 1/time. Because of the rate

of reaction is proportional to 1/time, so the rate of reaction increases with the increasing of the temperature where as the temperature is increasing, the faster the rate of reaction. 2. If more concentrated of sulphuric acid is used in the experiment, the time taken for the ‘X’ mark invisible is shorter. This is because concentrations also play roles in determining the rate of reaction. 3. The reason why the result from the experiment is varied from the actual result is usually caused by some error occurred during the experiment. The error might caused by the temperature that used is not well-controlled.

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ENHANCE

RAW MEAT

(A) BOIL IN WATER AT 1200C

(B) BOIL IN WATER AT 900C

Which condition that the meat will cook first? Explain why. Answer: The meat will cook first when it is cooked at condition (A) where the water temperature is at 1200C. This is because at a higher temperature, the rate of reaction is increase and the times taken for the meat to cook become shorter.

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