requird practical 3

Question 1

what is the aim of this practical?

Answer 1

to investigate how the rate of reaction changes with temperate

Question 2

what reaction are you investigating in this practical?

Answer 2

the reaction of sodium thiosulfate and hydrochloric acid
2HCl (aq) + Na2S2O3 (aq) -> 2NaCl (aq) + S (s) + SO2 (g) + H2O (l)

Question 3

what is a risk assessment for this practical?

Answer 3

hazard/risk/prevention
sodium thiosulfate solution and hydrochloric acid/irritation to skin or eyes/wear goggles, wash immediately if contact occurs
water bath/burns or scalds/wear heatproof gloves and avoid spilling water
glassware/cuts to skin/keep in centre of desk and clear up breakages

Question 4

what is the method for this practical?

Answer 4

1. use measuring cylinder to measure out 5cm3 of hydrochloric acid at room temperature into a beaker
2. place the beaker onto a white tile with a cross drawn on
3. use a measuring cylinder to measure out 20cm3 of sodium thiosulfate solution at room temperature
4. add the sodium thiosulfate solution to the hydrochloric acid, measure the starting temperature of the reaction and immediately start the timer
5. measure the time in seconds that it takes for the cross to disappear completely
6. measure the final temperature of the reaction mixture and calculate the average temperature for the reaction
7. repeat these steps using solutions from water baths at 40,60 and 80 degrees

Question 5

why does the reaction mixture go cloud causing the cross to disappear?

Answer 5

due to solid sulfur being produced

Question 6

how do calculate the rate of each reaction?

Answer 6

1/t to get rate in s^-1

Question 7

what do you do once you have calculate the rate of reaction for each experiment?

Answer 7

plot a graph with temperature on the x axis and rate of reaction on the y axis