Hey, I have a few questions that I'm not sure with and was wondering if anyone would be able to help me <3
1. A steel can may be placed with tin by electrolysis in an aqueous solution containing tin ions. The equation for the plating can be represented as Sn2+ (aq) + ne- --> Sn(s)
- Name the electrolyte and give its chemical composition
--> The answer for this was tin nitrate, but I'm not sure where the nitrate came from. Is it just a chem thing where the positively charged part of the electrolyte is always paired with nitrate?
2. Carbon monoxide reacts with chlorine gas to form phosgene, COCl2. At each of the two temperatures, T1 and T2, 1.0 mol Cl2 was mixed with 1.0 mol of CO in a 1.0 L container. The concentration of COCl2 was measured as a function of time in each experiment.
The diagram of the reaction is attached below (vv sorry that the quality sucks! it was taken on photobooth lol)
a. Explain why the concentration of COCl2 reached after long reaction times is different in the two experiments, and why in both experiments the concentration of COCl2 is less than 1.0 M.
b. Deduce whether the reaction is exothermic or endothermic. Explain your reason.
Thank you so much!!!
Hey!
In response to your quesions
1. For electroplating cells we know that the electrolyte must always contain the ion of the metal that undergoes reduction on the cathode. In this scenario, the cathode is the steel can and we want tin to be plated on it. Therefore, the electrolyte must contain the tin ion, Sn
2+. Recall that the electrolyte must always be made up of positive and negative charges so we currently have the positive ions, Sn
2+ but we need the negative ions. The negative ions could really be anything so long as it doesn't form a precipitate with Sn
2+, and since the nitrate ion tends to always form a soluble salt then a likely option for the electrolyte is tin nitrate.
2. a) We expect the concentration of COCl
2 to be less than 1.0 M because if this were true then that means that the reaction goes to completion where all of the CO and Cl
2 is used up. However, this this is an equilibrium reaction, we know that the concentration of CO and Cl
2 only decreases to some extent, but not fully. Therefore, we also expect the concentration of COCl
2, to increase by the same proportion in which CO and Cl
2 decrease.
b) Does the question tell you which temperature T
1 or T
2 is higher/lower? If not, I presume that T
2 is a higher temperature than T
1 just because it appears that the gradient of the curve corresponding to T
2 is initially steeper than T
1 (gradient on a concentration-time graph corresponds to the rate of reaction), and we know that higher temperature is associated with a greater rate of reaction. With that in mind, we can see that the yield of COCl
2 is higher when temperature is at T
1 than T
2 so this must mean that at a lower temperature, the forward reaction is favoured so therefore the reaction is exothermic.
Hope this helps/makes sense!