[Rutherford]

From dropper A into balloon B that contains 41g of butan-1-ol (apparatus is shown in the picture), during 20min, Na₂Cr₂O₇*2H₂O (m=56g) which contains sulfuric acid is slowly added . Balloon B was heated during the instilment, so distillation  continuously happens and that the temperature doesn't go above 80°C. After all dichromate was added, the balloon was heated for 15min, and the distillate was caught under 90°C. The composition of recipient C was dried over night with MgSO₄ and over-distillated (13 of distillate was obtained). What was the yield of this synthesis? What substances in what quantity are in balloon B after the reaction finished?
Compound-Boiling point
butan-1-ol   118°C
butanal       75°C
butan.acid   164°C

I balanced first:
-3C₄H₉OH+Cr₂O₇^2-+8H⁺ 2Cr³⁺+3C₃H₇CHO+7H₂O
-3C₃H₇CHO+Cr₂O₇^2-+8H⁺ 2Cr³⁺+3C₃H₇COOH+4H₂O
I know that in recipient C is C₃H₇CHO that was distillated, and in B left the acid and the alcohol that didn't react and weren't distillated. What to do now? There are two reactions how to calculate the yield? One only or for both, I don't understand ?

[discodermolide]

This is an oxidation reaction of butanol to the aldehyde. There is a difference of 2 mass units between them. If you started with 41g alcohol and got 13g aldehyde the yield is terrible (<40%).

 

[Rutherford]

Calculating that way I got the correct yield, but I god confused, too. How is this an oxidation of  butanol to the aldehyde if in the correct answer in balloon B left butanoic acid and butanol? If butanoic acid is present, then some of the aldehyde oxidized to the acid.

[discodermolide]

Calculating that way I got the correct yield, but I god confused, too. How is this an oxidation of  butanol to the aldehyde if in the correct answer in balloon B left butanoic acid and butanol? If butanoic acid is present, then some of the aldehyde oxidized to the acid.

That's correct over oxidation occurred. First the conversion to the aldehyde is s#*$ second it is easily oxidised to the acid. That's why they try and distill it out of the reaction.

[Rutherford]

If some of the aldehyde was converted to the acid, and then distilled, the mass 13g is be the mass of the aldehyde with the lost from making the acid, I thought that this wasn't accounted in the yield  . Now, to the second part:
I calculated the number of moles of butanol and the dichromate: n(butanol)=0.5441mol, n(dichr.)=0.1879mol and 0.1086mol of butanal (yield is 32.6%) was obtained at the end. I don't know how to calculate the mass of butanol and butanoic acid that left in balloon B.

[discodermolide]

If some of the aldehyde was converted to the acid, and then distilled, the mass 13g is be the mass of the aldehyde with the lost from making the acid, I thought that this wasn't accounted in the yield  . Now, to the second part:
I calculated the number of moles of butanol and the dichromate: n(butanol)=0.5441mol, n(dichr.)=0.1879mol and 0.1086mol of butanal (yield is 32.6%) was obtained at the end. I don't know how to calculate the mass of butanol and butanoic acid that left in balloon B.

This is accounted for inn the yield. 13g is the yield of aldehyde.
You can't calculate these values, as you do not have a yield for the formation of butyric acid.

[Rutherford]

I thought so, but it is asked in the problem. I suppose it is a mistake then. Thanks for the help.

[discodermolide]

I thought so, but it is asked in the problem. I suppose it is a mistake then. Thanks for the help.

My pleasure, bring on the next one:))