To Study the Effect of Temperature on Reaction Rate (Class 10 Chemistry Practical)
To observe how increasing temperature increases the rate of a chemical reaction.
TL;DR: To observe how increasing temperature increases the rate of a chemical reaction.
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Aim: To observe how increasing temperature increases the rate of a chemical reaction.
Materials Required
- Sodium thiosulfate solution
- Dilute hydrochloric acid
- Beakers
- Thermometer
- Stopwatch
- Water bath/hot plate
- White paper/tile
Theory
The rate of a chemical reaction increases with temperature. This is because higher temperature increases the kinetic energy of molecules, leading to more frequent and energetic collisions. In the reaction between sodium thiosulfate and HCl, a white precipitate (sulfur) forms, and the time taken to form it decreases at higher temperatures.
Procedure
- Take 25 mL of sodium thiosulfate solution in a beaker
- Record the initial temperature of the solution using a thermometer
- Add 5 mL of dilute HCl and immediately start the stopwatch
- Observe the solution from above against a white paper/tile and note the time when the precipitate is just visible (solution becomes turbid)
- Record the time taken for the white precipitate to form
- Repeat the experiment at different temperatures (30°C, 40°C, 50°C, 60°C, 70°C) by heating the sodium thiosulfate solution before adding HCl
- Plot a graph of temperature vs. time taken
- The graph will show an inverse relationship - higher temperature means less time
Observation
At 30°C, the white precipitate forms after [time] seconds. At 50°C, it forms after [shorter time] seconds. At 70°C, it forms in even less time. As temperature increases, the time taken for precipitate formation decreases, indicating faster reaction rate.
Result
The experiment demonstrates that increasing temperature increases the reaction rate. The time taken to form white sulfur precipitate decreases as temperature increases from 30°C to 70°C.
Precautions
- Ensure accurate temperature measurement before each trial
- Use the same volume and concentration of solutions for each trial
- Start the stopwatch immediately after mixing
- Observe the turbidity point consistently across all trials
- Allow solutions to cool before reheating to avoid temperature overshoot
Viva Questions
How does temperature affect reaction rate?
Increasing temperature increases reaction rate by providing molecules with more kinetic energy for faster collisions.
What is the white precipitate formed in this experiment?
The white precipitate is sulfur formed from the reaction between sodium thiosulfate and hydrochloric acid.
Why does the time decrease at higher temperatures?
At higher temperatures, molecules move faster and collide more frequently with greater energy, speeding up the reaction.
What is the relationship between temperature and reaction rate?
Reaction rate is directly proportional to temperature; approximately doubling for every 10°C increase (rough rule).
More Class 10 Chemistry Practicals
- To Prepare a True Solution and Observe the Tyndall Effect
- To Find the pH of Samples Using Indicators
- To Study a Double Displacement (Precipitation) Reaction
- To Test Acids and Bases with Indicators
- To Verify the Law of Conservation of Mass
- To Determine Melting and Boiling Points of a Pure Substance
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