Hello.
I have this question for my class.
We were to mix Na2S2O3 to a a test-tube with Varsol layer on top and an Aqueous layer (of I2/KI) on the bottom. I observed a lighter colour change in both layers. How would I express that as a chemical equation?
Also, I added saturated KI to a test-tube with the same two layers. The pink colour in Varsol got lighter and the colour in Aqueous solution also got lighter. How would I write this as a chemical equation?
Thanks
Sorry, my apologies.
After adding Na2S2O3, the Varsol layer became colorless and there was no change in the Aqueous layer.
Also forgot to include:
I2(aq) + I- <-> I3- (aq) = AQUEOUS LAYER
I2(aq) <-> I2 = VARSOL
To express the observed color changes in both scenarios as chemical equations, we need to consider the reactions taking place.
1. When Na2S2O3 is added to the test-tube with a Varsol layer on top and an aqueous layer of I2/KI at the bottom, the following reaction occurs:
2Na2S2O3 + I2 -> 2NaI + Na2S4O6
In this equation, Na2S2O3 (sodium thiosulfate) reacts with I2 (iodine) to form NaI (sodium iodide) and Na2S4O6 (sodium tetrathionate). The lighter color observed in both layers indicates that the iodine is being consumed in the reaction.
2. When saturated KI solution is added to the same test-tube with the Varsol and aqueous layers, the following reaction occurs:
2NaI + I2 -> 2I3- + 2Na+
In this equation, NaI (sodium iodide) reacts with I2 (iodine) to form I3- (triiodide ion) and Na+ (sodium ion). The lighter color observed in both layers indicates the reduction of iodine to the triiodide ion.
Overall, these chemical equations explain the observed lighter color changes in both the Varsol and aqueous layers when adding Na2S2O3 and saturated KI to the test-tube.