Displacement

CuSO4 Mg - Cu MgSO4Calculate the mass of magnesium needed to displace all of the copper from 100 cm3 of copper sulfate solutionConcentration of copper sulfate solution is 50 g CuSO4 per dm3

Reply 1

EierVonSatan

Original post by Manni8194

CuSO4 Mg - Cu MgSO4Calculate the mass of magnesium needed to displace all of the copper from 100 cm3 of copper sulfate solutionConcentration of copper sulfate solution is 50 g CuSO4 per dm3

Star by working out the moles of copper sulfate in the solution.

(edited 3 years ago)

Reply 2

Manni8194

Original post by EierVonSatan

Star by working out the moles of copper sulfate in the solution.

Then what do you do after that?

Reply 3

EierVonSatan

Original post by Manni8194

Then what do you do after that?

Use the balanced chemical equation to work out the number of moles of Mg needed to react.

Once you've got that it's easy to convert that to mass by using the A_r :yes:

Reply 4

Manni8194

Original post by EierVonSatan

Use the balanced chemical equation to work out the number of moles of Mg needed to react.

Once you've got that it's easy to convert that to mass by using the A_r :yes

K thank you 😊
Do you know the answer??

(edited 3 years ago)

Reply 5

EierVonSatan

Original post by Manni8194

K thank you 😊
Do you know the answer??

Yep. What did you get?

Reply 6

Manni8194

Original post by EierVonSatan

Yep. What did you get?

I tried to work it out but im confused on how to do it. I would really appreciate it if you showed me how to do it step by step. If not its okay thanks for ur help anyway. :smile:

Reply 7

EierVonSatan

Original post by Manni8194

I tried to work it out but im confused on how to do it. I would really appreciate it if you showed me how to do it step by step. If not its okay thanks for ur help anyway. :smile:

Instread of just giving you the answer, here is a similar question, done step by step (I am going to assume you are using a GCSE periodic table)

Mg + FeSO₄ ---> MgSO₄ + Fe
Calculate the mass of magnesium needed to displace all of the iron from 250 cm³ of iron (II) sulfate solution. The concentration of iron (II) sulfate solution is 12.0 g/dm³

Step 1: Working out the moles of iron sulfate present! If there are 12g in 1000cm³ (= 1 dm³), then there are 3g in 250cm³(i.e. dividing by 4)
to convert from g to mol, we use the formula moles = mass/Mr = 3g/(56+32+4x16) = 3/152 = 0.0197...mol of iron (II) sulfate

Step 2: From the balanced equation above, for every one FeSO₄ that gets reacted so does one Mg. Therefore, there is also going to be 0.0197...mol of magnesium needed to react all the FeSO₄

Step 3: We now need to convert the moles into mass, using the above formula. Mass = moles x A_r= 0.0197... x 24 = 0.474g (3sf)

Reply 8

Manni8194

Original post by EierVonSatan

Thank you soo much this helps a lot. I couldnt find this anywhere, thank u soooo much ur amazing 😊.And is the answer to my question 0.72?

(edited 3 years ago)

Reply 9

EierVonSatan

Original post by Manni8194

Thank you soo much this helps a lot. I couldnt find this anywhere, thank u soooo much ur amazing 😊.And is the answer to my question 0.72?

0.752g

moles of CuSO₄ = 0.0313... mol

1:1 ratio so 0.0313...mol of Mg

Mass = 0.0313...x24 = 0.752g

Reply 10

Manni8194

Original post by EierVonSatan

0.752g

moles of CuSO₄ = 0.0313... mol

1:1 ratio so 0.0313...mol of Mg

Mass = 0.0313...x24 = 0.752g

Hello its me again sorry :smile:

just wanted to say i followed ur example and technique and it helped, i know understand it so just wanted to say thank u sooo much for the help really appreciate it :smile:

Reply 11

EierVonSatan

Original post by Manni8194

Hello its me again sorry :smile:

just wanted to say i followed ur example and technique and it helped, i know understand it so just wanted to say thank u sooo much for the help really appreciate it :smile:

Very welcome!