Practical experiment 2 of a reaction between sodium thiosulfa solutions d iron (

Question

Practical experiment 2 of a reaction between sodium thiosulfa solutions d iron (IlI) nitrate The rate of solution is compared when different transition metal ions are catalysts used are copper(II), cobalt(I1) and iron(II) ions. reaction be tween iron (III) nitrate solution and sodium thiosulphate used as catalysts. The tron(I1) ions are reduced to iron(II) ions in the presence of sodiu tuoi proceeds via a dark-violet unstable complex but gives a colourless thiosuíphate. The reaction Eye protection Stop clock or timer Dropping pipette Glass measuring cylinder (100 cm Measuring cylinder (50 cm3) Conical flask Chemicals Access to 0.1 M solutions of the following: Cobalt chloride solution, CoCi2a (TOXIC), drops Copper (II) sulphate solution, CuSO4 drops Iron (II) sulphate solution, FeSO4(aa), drops Iron (III) nitrate solution, Fe(NO3)3.) 250 cm Sodium thiosulphate solution, Na2S203a) 250 cm Procedure a Draw a cross on a piece of scrap paper and put it underneath the 100 cm3 measuring cylinder so it can be seen when looking down the cylinder from the top. b Using the measuring cylinder, measure 50 cm3 of sodium thiosulfate solution. Pour the solution into a conical flask, which is placed on the paper sheet with drawn cross on it. c Using a 50 cm3 measuring cylinder, measure 50 cm3 of iron(III) nitrate solution. d Pour the iron(III) nitrate solution into the sodium thiosulfate solution in the conical flask and start the timer. An immediate dark-violet solution is observed which turns colourless after a few minutes. e Look through the reaction mixture from above until the cross can first be seen. Stop the timer and record the time.

Explanation / Answer

1. The best catalyst is CuSO4 (aq) as the time for completion of reaction is 0.04 seconds , lowest amongst the others. The worst catalyst is CoCl2 (aq) as the time for completion of reaction is 67 seconds , highest amongst the others.

2. The experimental procedure helps in explaining the effect of catalyst on the rate of reaction. A catalyst generally increases the rate of reaction and decreases the time for reaction completion. Here we can see that after the addition of catalyst the time for reaction decreases. different catalysts have different effects on the rate & hence time for reaction. Here we can see by employing CuSO4 (aq) as catalyst the time for reaction decreases to 0.04 seconds from 64 seconds hence the rate of reaction increases. As rate of reaction is inversly proprtional to time of reaction.

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