Photo AI
A stopwatch was started when 50 cm³ of a 0.20 M sodium thiosulfate solution was poured into a conical flask containing 10 cm³ of 1.0 M HCl solution - Leaving Cert Chemistry - Question 3 - 2010
Question 3
A stopwatch was started when 50 cm³ of a 0.20 M sodium thiosulfate solution was poured into a conical flask containing 10 cm³ of 1.0 M HCl solution. The conical flas... show full transcript
Worked Solution & Example Answer:A stopwatch was started when 50 cm³ of a 0.20 M sodium thiosulfate solution was poured into a conical flask containing 10 cm³ of 1.0 M HCl solution - Leaving Cert Chemistry - Question 3 - 2010
Step 1
Step 2
Describe a procedure for diluting the 0.20 M sodium thiosulfate solution to give 50 cm³ of a 0.12 M solution.
Answer
To prepare 50 cm³ of a 0.12 M sodium thiosulfate solution from a 0.20 M stock solution, measure 30 cm³ of the 0.20 M sodium thiosulfate solution using a pipette. Dilute this with distilled water to bring the final volume up to 50 cm³. This will involve adding 20 cm³ of distilled water. Ensure thorough mixing to obtain a homogeneous solution.
Step 3
Plot a graph to record the relationship between the rate of reaction and the concentration of sodium thiosulfate.
Answer
To plot the graph, use the data from the table. The x-axis will represent the concentration of sodium thiosulfate (M), and the y-axis will represent the rate of reaction (1/t min⁻¹). Carefully plot each point based on the provided values:
- (0.20, 0.71)
- (0.16, 0.62)
- (0.12, 0.56)
- (0.08, 0.34)
- (0.04, 0.12)
- (0.02, 0.09)
After plotting, draw a straight line to represent the linear relationship observed.
Step 4
Use your graph to predict the time taken for 50 cm³ of 0.20 M sodium thiosulfate to react with 10 cm³ of 1.0 M hydrochloric acid.
Answer
From the graph, for 50 cm³ of 0.20 M sodium thiosulfate, the corresponding reaction time is approximately 1.4 minutes. This value can be read directly from the plotted graph, corresponding to the highest concentration.
Step 5
Would you expect the reaction rate to increase, decrease, or stay the same, as the temperature was increased? Justify your answer.
Answer
The reaction rate would likely increase with an increase in temperature. This is due to the fact that higher temperatures provide reactant molecules with more kinetic energy, which increases the frequency of collisions and allows more particles to overcome the activation energy barrier. Consequently, the likelihood of successful collisions increases, leading to an increased reaction rate.