I have potassium dichromate and I placed a pipet with a sample in it in ice wate
ID: 537257 • Letter: I
Question
I have potassium dichromate and I placed a pipet with a sample in it in ice water and then in hot water.
Is this reaction endothermic or exothermic and how can you tell?
2K2CrO4 + 2HCl <--> Cr2O7 + H2O + 2KCl
When the dichromate was placed into the ice water, the mixture turned a lighter orange. Which way is the chemical system shift?
When the dichromate was placed into the hot water, the mixture turned a darker orange. Which way is the chemical system shift?
Below is the full question, I just pointed out specific points I need help with above.
A. Discuss the observations in complete sentences. Write the chemical reaction and explain if your data supports this reaction being endothermic or exothermic in the forward direction. Include the equilibrium expression in your answer. (10pts) Remember that the forward reaction can only be exothermic OR endothermic and not both. Watch the colors. Initially (before they are mixed) what color are the reactants? Once they are mixed, what color is the reaction? If the reactants are yellow and the products are blue, the equilibrium will be green. Knowing this, what can you surmise about reaction and which way it shifts?
ata Table 2. Endothermic and Exothermic Shifts. Reaction at Room Reaction in Cold Water Reaction in Hot Water Bath Bath Temperature slightly or The orange seems to lighter have darkened. When When swirled, you can see swirled, the yellow hue a yellow hue. Also, it looks does not stand out as to be that there are tiny much, compared to Color orange solid crystals that have when it was submerged formed and have gathered at bottom in ice water. Also, the the of the pipet crystal zed fragments in a group. are no longer there Chemical System Shift Left or RightExplanation / Answer
First of all colour of K2CrO4 is yellow and colour of K2Cr2O7 is Orange.
For an exothermic reaction, heat is essentially a product of the reaction. In keeping with Le Chatelier's principle, if you increase the temperature you are increasing the amount of products, and so you shift the balance at equilibrium back toward reactants, meaning there will be more reactants left at equilibrium, Which is opposit for endothermic reaction.
The above reaction is Endothermic in the forward direction, that means the reaction mixture becomes colder on reaction. When you put the reaction mixture in ice water , we are decreasing the temperature of the reacion mixture even more , which hamper the forward reaction and favours backward reaction. As a result concentration of K2CrO4(yellow) increase and reaction mixture looks Light Orange.
When you put the reaction mixture in hot water , we are increasing the temperature of the reacion mixture, which favours the forward reaction and favours forward reaction. Reaction shifts in Forward Direction. As a result concentration of K2CrO4(yellow) decrease & K2Cr2O7(orange) increases and as a result reaction mixture looks Dark Orange.