Question

According to the reaction 2AgNO3 + Cu -> Cu(NO3)2 + 2 Ag, how many grams of copper(II)Nitrate will be formed upon the complete reaction of 26.8 g of Cu with excess silver nitrate?

Answer 1

i'm a bit confused when the problem asks "with excess silver nitrate."

Answer 2

i'm a bit confused when the problem asks "with excess silver nitrate."

Answer 3

ok, AgNO3 is in excess,what does this tells you about the reaction?

Answer 4

uhm, after the reaction there will be a lot of AgNO3 left over?

Answer 5

yes thats absolutely right, and more importantly, your Cu will be completely gone by the end of this reaction

Answer 6

ok makes sense

Answer 7

also, do you know how to calculate the mass percentage of CU in Cu(NO3)2

Answer 8

is that like % yield=(actual/theo.) *100% ?

Answer 9

yes, the formula is similiar and thats becuase these two are very similiair idea. In mass percentage you are asking how much Cu are there in Cu(NO3)2, which is molar mass of Cu/molar mass of Cu(NO3)2

Answer 10

remember this formula, cuz I'll use it later

Answer 11

ok

Answer 12

now since Cu is completely reacted, that means the mass of Cu in Cu(NO3)2 is 26.8g

Answer 13

does this makes sense

Answer 14

yes

Answer 15

OK now lets set the mass of Cu(NO3)2 at the end of reaction is x grams

Answer 16

we know the mass percentage of Cu in Cu(NO3)2, so mass percentage * X is mass of Cu which is 26.8

Answer 17

its simililar to percentage yield indeed. In percentage yield questions, we have the percentage yeild * theortical=actual

Answer 18

here we have mass percentage of Cu * mass of Cu(NO3)2=mass of Cu

Answer 19

and now you just solve for mass of Cu(NO3)2, and thats your answer

Answer 20

this is a bit confusing, because its a little different from the way we were taught in class

Answer 21

yea, Im doing a shortcut way

Answer 22

because its much easier once you are familiar with it

Answer 23

i thought you had to convert grams of Cu to grams of Cu(NO3)2

Answer 24

thats exactly what the mass percentage is doing

Answer 25

oh, but with less calculations?

Answer 26

it converts mass of Cu(NO3)2 to mass of Cu

Answer 27

srry, but i thought the question asked for how many grams of Cu(NO3)2 can be formed from grams of Cu?

Answer 28

Ok, let me work it out in full detail

Answer 29

molar mass of Cu is 64, molar mass of Cu(NO3)2 is 188

Answer 30

therefore mass percentage of Cu in Cu(NO3)2 is 64/188=0.34

Answer 31

good so far?

Answer 32

yes

Answer 33

let the mass of Cu(NO3)2 at the end of reaction be x

Answer 34

since we have 26.8g of Cu to start with and it completely racted, we must end up with 26.8g of Cu in Cu(NO3)2 becuase of conservation of mass

Answer 35

understood this part?

Answer 36

yea

Answer 37

now since we have x grams of CU(NO3)2, and 0.34 of it is Cu, so we have 0.34*x=26.8grams

Answer 38

cool?

Answer 39

78.8 grams? of Cu(NO3)2?

Answer 40

great! that the right answer

Answer 41

well done!

Answer 42

it sorta makes sense, ty for the response

Answer 43

NP, if you keep practing this sort of problem, it will become natural for you to think this way

Answer 44

yea chem is slower for me, just doing this to fill an elective, thx again