Cr2O3 + 3CCl4 ---> 2CrCl3 + 3CCl2O
In one experiment, 6.37 grams of Cr2O3 was treated wiht excess CCl4 and yielded 8.75 grams of CrCl3. What was the percent yeild?
I have no idea how to do this. I know that percent yield is actual/theorectical yield *100.
And i know how to do this type of problem when the problem has the words is produced in it. Because what is produced is the actual yield. But how would i do this problem since it doesn't say is produced?
Can anyone help me, thanks:)
Not smart. Persistent.
I worked the problem and found mass CrCl3 of about 13 grams or so as the theoretical yield. Actual yield of 8.75 g which makes the % yield about 60% give or take a little. Check me out on that. Sometimes I punch the wrong numbers on the calculator.
It "yielded" 8.75 g CrCl3. That means it produced that many grams. What you must do is calculate how much CrCl3 SHOULD have been formed, using 6.37 g Cr2O3 as a starting material. That amount that should have been formed is the theoretical yield.
Thank you for your help! :) You are very smart!
To calculate the percent yield in this problem, you need to find the theoretical yield and the actual yield.
The theoretical yield is the amount of product you would expect to obtain if the reaction went to completion. You can calculate this by using the stoichiometry of the balanced chemical equation. In this case, the stoichiometry tells us that 1 mole of Cr2O3 reacts with 2 moles of CrCl3.
First, convert the mass of Cr2O3 given (6.37 grams) to moles by dividing it by the molar mass of Cr2O3 (a periodic table will help here). Then, use the mole ratio from the balanced equation to convert moles of Cr2O3 to moles of CrCl3. Finally, multiply the moles of CrCl3 by its molar mass to obtain the theoretical yield in grams.
Next, the actual yield is the mass of product that was actually obtained in the experiment, which is given as 8.75 grams of CrCl3.
Now, you can use the formula for percent yield:
Percent yield = (actual yield/theoretical yield) * 100
Plug in the values you found for the actual and theoretical yields to calculate the percent yield.