# Percentage yield quesions

#1
CAN SOMONE HELP ME WITH THESE PLEASE?
Q1: Reaction of 1.274 g of aqueous copper sulfate with excess zinc metal
produced 0.392 g of copper metal according to the equation shown:
CuSO4(aq)+Zn(s) → Cu(s)+ZnSO4(s)
Calculate, to the nearest whole number, the percentage yield of this reaction.
Q2: 20 g of NaAlH4 reacts with 10 g of LiCl to produce 8.3 g of LiAlH4:
NaAlH4 + LiCl → LiAlH4 + NaCl
What is the percentage yield for this reaction?

Q3: 1 mole of propane is burned using 7 moles of oxygen according to the following
43 | P a g e
equation:
C3H8+O2 → H2O + CO2
By balancing the equation, identify the limiting reagent for this reaction.
A C3H8
B O2
C Neither
Q4: Harder! You need to write a balanced equation before you can answer this!
A student treated 15 g of copper(II) oxide with excess hydrochloric acid and
purified the copper(II) chloride product by recrystallization. The final mass of pure
copper(II) chloride was 11 g. What was the percentage yield?
0
7 months ago
#2
For Task i) Q1, you need to work out the number of moles of copper sulfate, you are given the mass of it. Then you look at the equation, what is the ratio of the number of moles between copper sulfate reacted and the copper metal produced? (You don't need to worry about the zinc metal as it is in excess) From the equation, you would then know the number of moles of copper metal, you work out the theoretical mass of copper metal produced by using the Mr of Copper multiplied by the number of moles of copper that you just worked out, and finally you find the percentage yield by using the equation: (Actual Mass/Theoretical mass) x 100

You can work out the percentage yield by working out the theoretical moles of copper and then compare it to the actual moles of copper produced, it's a personal preference really.

Q2 is of a similar idea, try to do it yourself if you are able to.

For Q3, it would be helpful to draw out a table with the number of reactant atoms on one side and the number of product atoms on the other side, and balance the atoms on either side, continue to do this until the number of atoms is balanced on both sides (Sometimes balancing certain atoms would automatically cause other atoms to be balanced).

For Q4, this is a neutralisation reaction, as it is a base (copper(II) oxide) reacting with an acid (HCl), you need to recall the general equation for acid-base reactions, you then need to balance the equation, find the number of moles of copper(II) oxide reacted, and then find the percentage yield of the reaction by working out the number of moles of copper(II) chloride produced or the theoretical mass of copper(II) chloride by comparing the ratio of moles in the equation.
0
#3
(Original post by Sodium229)
For Task i) Q1, you need to work out the number of moles of copper sulfate, you are given the mass of it. Then you look at the equation, what is the ratio of the number of moles between copper sulfate reacted and the copper metal produced? (You don't need to worry about the zinc metal as it is in excess) From the equation, you would then know the number of moles of copper metal, you work out the theoretical mass of copper metal produced by using the Mr of Copper multiplied by the number of moles of copper that you just worked out, and finally you find the percentage yield by using the equation: (Actual Mass/Theoretical mass) x 100

You can work out the percentage yield by working out the theoretical moles of copper and then compare it to the actual moles of copper produced, it's a personal preference really.

Q2 is of a similar idea, try to do it yourself if you are able to.

For Q3, it would be helpful to draw out a table with the number of reactant atoms on one side and the number of product atoms on the other side, and balance the atoms on either side, continue to do this until the number of atoms is balanced on both sides (Sometimes balancing certain atoms would automatically cause other atoms to be balanced).

For Q4, this is a neutralisation reaction, as it is a base (copper(II) oxide) reacting with an acid (HCl), you need to recall the general equation for acid-base reactions, you then need to balance the equation, find the number of moles of copper(II) oxide reacted, and then find the percentage yield of the reaction by working out the number of moles of copper(II) chloride produced or the theoretical mass of copper(II) chloride by comparing the ratio of moles in the equation.
thank you so much and sorry for the late reply
0
6 months ago
#4
(Original post by CuriousSeeker)
thank you so much and sorry for the late reply
No problem and it's okay
0
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