R.P 3 (Effect of temperature on rate) Flashcards
Outline the 5 steps in the method of approximating the initial rate of this reaction
Na2S2O3 + 2HCl —> 2NaCl + SO2 + S + H2O
*Measure 10 cm3 of 0.2M hydrochloric acid and 10 cm3 of sodium thiosulfate in separate clean measuring cylinders. Put the solutions in separate boiling tubes
*Choose a temperature to investigate use water bath to get the two solutions to that temperature by placing the boiling tubes in the water bath.
*Place the flask on the centre of the large cross; first add the sodium thiosulfate to the flask. Then add the hydrochloric acid and start the stopwatch and swirl to mix the solutions.
*Stop the clock when the cross disappears and note the time.
*Repeat the experiment for four more different temperatures (maximum temperature should be 70 degrees C).
Cloudiness is from production of S
How can we use the results of initial rate to calculate activation energy
The Arrhenius equation can be rearranged
ln k = constant – Ea/(RT)
y = c + mx
y axis: ln(rate)
x axis: 1/T
k is proportional to the rate of reaction so ln k can be
replaced by ln(rate)
From plotting a graph of ln(rate) or ln k against 1/T the activation energy can be calculated from measuring the gradient of the line
