[Extragum]

Hey guys I have a chemistry assignment due on March 6th and though I'm having trouble undestanding some of the questions I think I'll be able to get them even with the confusing examples from the book. Right now the only problem in the assignment that I can't figure out is this one and the chapter in the book might have confused me even more  . I would appreciate any help I could get with the explanation of this problem and would especially appreciate a tiny walkthrough if you have the time. Alright so heres the question and also does anyone know of a way to learn a certain type of problem when the chapter in the book does not explain it thoroughly enough?

In a chemical reaction (unbalanced equation), C2H6O + PCl3 = C2H5Cl + H3PO3, when the reaction was carried out, the actual yield of C2H5Cl was calculated 97.3 % of the theoretical value. If the theoretical yield should have been 2.04 mol, how many grams of C2H5Cl were actually obtained?

[Astrokel]

You could check out online resources such as: http://en.wikipedia.org/wiki/Chemical_yield or just google. Alternatively, you can post your problems here we will try to help you only if you show your attempts!

Actual yield is different from theoretical yield due to errors when you carried out experiments or even side reactions and many more. Therefore, theoretical yield is what you would expect to obtain if you calculate it 'theoretically' from the reaction but in actual fact, it is less than this amount.

[killerbeehead]

To solve this problem, first find the moles of actual yield by multiplying the theoretical yield by the % actual yield. Now you have the actual moles of product. Moles relates to grams through a equivalence known as the "chart weight." You can find chart weight by adding the "g/mol" value for each atom in the molecule. Now, multiply the number of moles by the weight of each mol, and you'll have the actual mass. Think of moles as a number quantity unit defined by Avogadro's number. If I have 1 mole of HCl in solution, I have 6.022E23 molecules of HCL. Using g/mol, you can find the mass of your product. Here's a simple example to analogize this problem. Imagine I'm going to buy 3 cars, but I lose some of my money on the way to the dealer and only have 66.666% of money to buy cars. I buy what I can with the remaining money, and if each car weighs 1000kg, I want to know the total mass of cars I own. Obviously, I can now only afford 2 cars, so I buy two cars, and I multiply the total number of cars by the mass of each one to find the total mass of cars, 2000 kg. Apply this to your problem and you should figure it out.

[Vidya]

97.3 % of the theoretical value=moles of C2H5Cl

 
1 mole of C2H5Cl =  molar mass of C2H5Cl

Grams of C2H5Cl    =   moles of C2H5Cl X molar mass of C2H5Cl
 

[Extragum]

Thanks for your help I think I'm understanding. Theres still a couple problems on the work that I don't understand but I don't think they'll cause as big of a problem as that question. So thanks again guys.