If 20g of CaC2 are required what mass of carbon must be reacted using equation...?

If 20g of CaC2 are required what mass of carbon must be reacted using equation...?
CaO(s) + 3 C(s) ----> CaC2(s) + CO (g)

Reply 1

WhatamIdoing

12

Moles = Mass/RFM.
Compare ratios. HINT: They're not the same.
Rearrange moles = mass/RFM using the moles obtained from the ratio.

Reply 2

Eat.Sleep.Row.Repeat.

8

Original post by sweetsummer

If 20g of CaC2 are required what mass of carbon must be reacted using equation...?
CaO(s) + 3 C(s) ----> CaC2(s) + CO (g)

Well you need to work out the moles of CaC2 in 20g. That's Mass/Mr. Then look at the stoicheiometry (numbers in front of each chemical) and see how many moles of C are needed. Use the moles = mass/mr equation again, and you have your answer.

Reply 3

F1's Finest

21

Original post by sweetsummer

If 20g of CaC2 are required what mass of carbon must be reacted using equation...?
CaO(s) + 3 C(s) ----> CaC2(s) + CO (g)

look at the molar ratio of

CaC2 to C

its 1 to 3

so first work out the number or moles of CaC2 which is worked out by the formula moles = mass / Molar Mass

Moles of CaC2 = 40.1 + (12*2) = 64.1

now do 20 / 64.1 = 0.31 moles.

divide this number by 3 to work out the moles of C

so 0.31/3 = 0.1 moles

now we know that 0.1 moles of C is used up

manipulate the moles equation to get Molar Mass * moles = mass

12 (mass of carbon) *0.1 moles = 1.2g

Reply 4

amongsttheweeds

18

Turn the mass of CaC2 into moles using the moles = mass/Mr formula, and correct for the ratios (given in the equation) - is there more or less carbon required than CaC2? Then turn the number of moles of C2 required back into a mass using the Mr and reusing that equation.

Reply 5

amongsttheweeds

18

Original post by James A

look at the molar ratio of

CaC2 to C

its 1 to 3

so first work out the number or moles of CaC2 which is worked out by the formula moles = mass / Molar Mass

Moles of CaC2 = 40.1 + (12*2) = 64.1

now do 20 / 64.1 = 0.31 moles.

divide this number by 3 to work out the moles of C

so 0.31/3 = 0.1 moles

now we know that 0.1 moles of C is used up

manipulate the moles equation to get Molar Mass * moles = mass

12 (mass of carbon) *0.1 moles = 1.2g

Nice one for just giving the answer. Are you really helping him?

Reply 6

sweetsummer

OP

5

Original post by James A

look at the molar ratio of

CaC2 to C

its 1 to 3

so first work out the number or moles of CaC2 which is worked out by the formula moles = mass / Molar Mass

Moles of CaC2 = 40.1 + (12*2) = 64.1

now do 20 / 64.1 = 0.31 moles.

divide this number by 3 to work out the moles of C

so 0.31/3 = 0.1 moles

now we know that 0.1 moles of C is used up

manipulate the moles equation to get Molar Mass * moles = mass

12 (mass of carbon) *0.1 moles = 1.2g

Shouldn't you multiply the 0.3 moles of CaC2 by 3 not divide to get the 3C of carbon? :s