# urgent chemistry help needed!!!!!

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Hi guys, I really need help with this question as i think it might come up in my mock on monday. This is the question

A copper sulfate solution contained 0.100 moles of copper sulfate dissolved

in 0.500 dm3 of water.

Calculate the mass of copper sulfate in 30.0 cm3 of this solution.

Relative formula mass (Mr): CuSO4 = 159.5

please help!!!

A copper sulfate solution contained 0.100 moles of copper sulfate dissolved

in 0.500 dm3 of water.

Calculate the mass of copper sulfate in 30.0 cm3 of this solution.

Relative formula mass (Mr): CuSO4 = 159.5

please help!!!

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#2

(Original post by

Hi guys, I really need help with this question as i think it might come up in my mock on monday. This is the question

A copper sulfate solution contained 0.100 moles of copper sulfate dissolved

in 0.500 dm3 of water.

Calculate the mass of copper sulfate in 30.0 cm3 of this solution.

Relative formula mass (Mr): CuSO4 = 159.5

please help!!!

**lol9812**)Hi guys, I really need help with this question as i think it might come up in my mock on monday. This is the question

A copper sulfate solution contained 0.100 moles of copper sulfate dissolved

in 0.500 dm3 of water.

Calculate the mass of copper sulfate in 30.0 cm3 of this solution.

Relative formula mass (Mr): CuSO4 = 159.5

please help!!!

If 0.1 moles are present in 0.500

**dm3**, then how many moles would be present in 30

**cm3**?

This is normal ratio/proportion calculations that I’m sure you can do do make sure to convert the dm3 to cm3

Once you have your answer, use the formula of moles = mass / Molecular Mass to find the mass of Copper Sulfate in 30cm3

Last edited by qwert7890; 1 month ago

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(Original post by

I can help you get to the answer because it’s technically cheating

If 0.1 moles are present in 0.500

This is normal ratio/proportion calculations that I’m sure you can do do make sure to convert the dm3 to cm3

Once you have your answer, use the formula of moles = mass / Molecular Mass to find the mass of Copper Sulfate in 30cm3

**qwert7890**)I can help you get to the answer because it’s technically cheating

If 0.1 moles are present in 0.500

**dm3**, then how many moles would be present in 30**cm3**?This is normal ratio/proportion calculations that I’m sure you can do do make sure to convert the dm3 to cm3

Once you have your answer, use the formula of moles = mass / Molecular Mass to find the mass of Copper Sulfate in 30cm3

I did this: 500dm3=500000cm3 so therefore i did 0.1 moles divided by 500000 to find the amount of moles present in 1cm3- i then multiplyied that by 30 and substituted it into the equation however my answer still doesnt look right

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#4

(Original post by

Hi thankyou so much for your reply!! I think i have still got it wrong however and im really stressed I got 9.5 x 10^(-4)

I did this: 500dm3=500000cm3 so therefore i did 0.1 moles divided by 500000 to find the amount of moles present in 1cm3- i then multiplyied that by 30 and substituted it into the equation however my answer still doesnt look right

**lol9812**)Hi thankyou so much for your reply!! I think i have still got it wrong however and im really stressed I got 9.5 x 10^(-4)

I did this: 500dm3=500000cm3 so therefore i did 0.1 moles divided by 500000 to find the amount of moles present in 1cm3- i then multiplyied that by 30 and substituted it into the equation however my answer still doesnt look right

The equivalent of 0.500dm3 is equal to 500 cm3. So 0.1 moles in 500cm3, so 1cm3 will have 2x10^-4 moles.

Then multiply this by 30 to get number of moles of Copper Sulfate. Then multiply this by Mr of Copper Sulfate to get mass of copper Sulfate.

Cheers

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(Original post by

Your strategy is right, but is it 500dm3 or 0.500 dm3?

The equivalent of 0.500dm3 is equal to 500 cm3. So 0.1 moles in 500cm3, so 1cm3 will have 2x10^-4 moles.

Then multiply this by 30 to get number of moles of Copper Sulfate. Then multiply this by Mr of Copper Sulfate to get mass of copper Sulfate.

Cheers

**qwert7890**)Your strategy is right, but is it 500dm3 or 0.500 dm3?

The equivalent of 0.500dm3 is equal to 500 cm3. So 0.1 moles in 500cm3, so 1cm3 will have 2x10^-4 moles.

Then multiply this by 30 to get number of moles of Copper Sulfate. Then multiply this by Mr of Copper Sulfate to get mass of copper Sulfate.

Cheers

Last edited by lol9812; 1 month ago

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#6

(Original post by

Thankyou so much I think i have the right answer now x

**lol9812**)Thankyou so much I think i have the right answer now x

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(Original post by

No problem what did you get

**qwert7890**)No problem what did you get

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#9

(Original post by

I got 0.957g x

**lol9812**)I got 0.957g x

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(Original post by

did you round it correctly?. to 3 s.f i got 0.956g

**14nmathew**)did you round it correctly?. to 3 s.f i got 0.956g

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#11

(Original post by

I did 6x10^-3 x 159.5 which =0.957 so i would round it up to 0.96

**lol9812**)I did 6x10^-3 x 159.5 which =0.957 so i would round it up to 0.96

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#12

(Original post by

I did 6x10^-3 x 159.5 which =0.957 so i would round it up to 0.96

**lol9812**)I did 6x10^-3 x 159.5 which =0.957 so i would round it up to 0.96

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(Original post by

Your answer is correct

**qwert7890**)Your answer is correct

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#16

(Original post by

i got 9.57g

**stormtd_**)i got 9.57g

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#17

converted 30.0 cm3 ----- 0.03 dm3

concentration in mol/dm3 = amount of solute in mol / volume in dm3

0.100/0.500 = 0.2 mol = concentration of copper sulfate

0.2 x 0.003 = 0.06mol

0.06 x 159.5 = 9.57

concentration in mol/dm3 = amount of solute in mol / volume in dm3

0.100/0.500 = 0.2 mol = concentration of copper sulfate

0.2 x 0.003 = 0.06mol

0.06 x 159.5 = 9.57

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#18

(Original post by

Post your working! You’ve multiplied by x100 at some step mistakenly (or missed out on dividing by 100)

**qwert7890**)Post your working! You’ve multiplied by x100 at some step mistakenly (or missed out on dividing by 100)

concentration in mol/dm3 = amount of solute in mol / volume in dm3

0.100/0.500 = 0.2 mol = concentration of copper sulfate

0.2 x 0.003 = 0.06mol

0.06 x 159.5 = 9.57

hi can you check what i have done wrong?

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#19

(Original post by

converted 30.0 cm3 ----- 0.03 dm3

concentration in mol/dm3 = amount of solute in mol / volume in dm3

0.100/0.500 = 0.2 mol = concentration of copper sulfate

0.2 x 0.003 = 0.06mol

0.06 x 159.5 = 9.57

hi can you check what i have done wrong?

**stormtd_**)converted 30.0 cm3 ----- 0.03 dm3

concentration in mol/dm3 = amount of solute in mol / volume in dm3

0.100/0.500 = 0.2 mol = concentration of copper sulfate

0.2 x 0.003 = 0.06mol

0.06 x 159.5 = 9.57

hi can you check what i have done wrong?

also how did you get 0.06 mol for it you would get 6 x 10^-4 mol

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#20

(Original post by

You did 0.2 x 0.003 it is meant to be 0.2 x 0.03

also how did you get 0.06 mol for it you would get 6 x 10^-4 mol

**!AXEL!**)You did 0.2 x 0.003 it is meant to be 0.2 x 0.03

also how did you get 0.06 mol for it you would get 6 x 10^-4 mol

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