a level chem help
ZnO + 2HCl -> ZnCl2 + H20
We're asked to calculate the mass of ZnCl2. We're given the conc and vol of HCl, so we have to calculate the moles of HCl then divide this number by 2 to give you the moles in ZnCl2. Then use this to find the mass of ZnCl2.
Thing is, we're also given the moles of ZnO, so why can't we use this to workout the moles in ZnCl2 since the ratio's 1:1?
We're asked to calculate the mass of ZnCl2. We're given the conc and vol of HCl, so we have to calculate the moles of HCl then divide this number by 2 to give you the moles in ZnCl2. Then use this to find the mass of ZnCl2.
Thing is, we're also given the moles of ZnO, so why can't we use this to workout the moles in ZnCl2 since the ratio's 1:1?
Original post by quickquestion805
ZnO + 2HCl -> ZnCl2 + H20
We're asked to calculate the mass of ZnCl2. We're given the conc and vol of HCl, so we have to calculate the moles of HCl then divide this number by 2 to give you the moles in ZnCl2. Then use this to find the mass of ZnCl2.
Thing is, we're also given the moles of ZnO, so why can't we use this to workout the moles in ZnCl2 since the ratio's 1:1?
We're asked to calculate the mass of ZnCl2. We're given the conc and vol of HCl, so we have to calculate the moles of HCl then divide this number by 2 to give you the moles in ZnCl2. Then use this to find the mass of ZnCl2.
Thing is, we're also given the moles of ZnO, so why can't we use this to workout the moles in ZnCl2 since the ratio's 1:1?
One of the reactants will be the limiting reagent, and the other in excess – can you work out which is which?
Original post by bl0bf1sh
One of the reactants will be the limiting reagent, and the other in excess – can you work out which is which?
hmm not sure, tell me
Original post by quickquestion805
hmm not sure, tell me
You'll need to use the information given and compare moles
Original post by quickquestion805
ZnO + 2HCl -> ZnCl2 + H20
We're asked to calculate the mass of ZnCl2. We're given the conc and vol of HCl, so we have to calculate the moles of HCl then divide this number by 2 to give you the moles in ZnCl2. Then use this to find the mass of ZnCl2.
Thing is, we're also given the moles of ZnO, so why can't we use this to workout the moles in ZnCl2 since the ratio's 1:1?
We're asked to calculate the mass of ZnCl2. We're given the conc and vol of HCl, so we have to calculate the moles of HCl then divide this number by 2 to give you the moles in ZnCl2. Then use this to find the mass of ZnCl2.
Thing is, we're also given the moles of ZnO, so why can't we use this to workout the moles in ZnCl2 since the ratio's 1:1?
There are two ways of calculating the moles of the ZnCl2 in the equation, like you said, you can work out the moles of HCL or ZnO. Does this question have multiple parts? They usually give you extra info like the conc of hcl if you need to use it in another question.
I would use the 1:1 ratio of ZnO, but make sure you learn how to do it with the HCL, too, as this is a VERY common exam question!!
Original post by bl0bf1sh
You'll need to use the information given and compare moles
There are 0.083 moles of ZnO and 0.12 of HCl, so HCl would be in excess. I still don't understand why you'd use HCl to find the moles and not ZnO. Thanks for the help btw
Original post by Sheepwool
There are two ways of calculating the moles of the ZnCl2 in the equation, like you said, you can work out the moles of HCL or ZnO. Does this question have multiple parts? They usually give you extra info like the conc of hcl if you need to use it in another question.
I would use the 1:1 ratio of ZnO, but make sure you learn how to do it with the HCL, too, as this is a VERY common exam question!!
I would use the 1:1 ratio of ZnO, but make sure you learn how to do it with the HCL, too, as this is a VERY common exam question!!
Ah I see, but it doesn't seem to be working for this particular question. Could it be something to do with one reactant being in excess, like the user above explained?
Original post by quickquestion805
There are 0.083 moles of ZnO and 0.12 of HCl, so HCl would be in excess. I still don't understand why you'd use HCl to find the moles and not ZnO. Thanks for the help btw
No this is very strange, if the HCl is in excess, then you would use the ratio for the ZnO as all of the HCl wouldn’t have reacted to form the product. Are you sure you were meant to use the HCl moles? Or were you just meant to see which was in excess? Regardless to what you are told, use the ZnO moles, you are completely correct with what you are saying. Always use the moles of the reactant that is not in excess.
Original post by quickquestion805
There are 0.083 moles of ZnO and 0.12 of HCl, so HCl would be in excess. I still don't understand why you'd use HCl to find the moles and not ZnO. Thanks for the help btw
Is HCl definitely in excess? Have a careful look at the molar ratio…
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