reactions with magnesium?

Question

magnesium reacts with carbon dioxide to produce magnesium oxide and carbon. How much carbon dioxide is required to react with 6g magnesium?


I tried it and got this:

2Mg + CO2 --> 2MgO + C

48g 44g 80g 12g

then i divided 48 by 6 and got 8 so i then divided the 44g of CO2 by 8 and got my answer to 5.5g of CO2 required.


I don't think it's right though cos it seemed to straight forward to just divide it all. Could someone give me some help if its totally wrong?

Thanks guys

Answer 1

first, you should know the atomic relative mass of Mg.
the atomic relative mass is 24.

6 grams of Mg = 0.25 moles.

from your reaction above, we know that it need 0.125 moles CO2.

the molecul relative mass of CO2 is 44.
0.125 X 44 = 5.5 grams.

Answer 2

I will certainly try for ya... wow, I haven't studied Chemistry for years, I got a grade A at A-level but that was way long ago! Let's see how good my memory is....

...if it serves correct you have to use the molar weight to solve problems like this... ie. use its molecular weight from the periodic table converted into grams.

1 mole of magnesium = 24g (from its atomic mass 24)
1 mole of CO2 = 12 + (2x16) = 44g

Therefore 48g of magnesium reacts with 44g of CO2, so 6g will react with 5.5g.

As far as I can see, you are spot on dude! Dont take my word for it tho, I finished my A levels in 1993!

Answer 3

First bit is OK!
48 g of Mg react with 44 g of CO2
So 1 g of Mg reacts with 44/48 9 CO2
So 6 g of Mg react with 6 X 44/48
This is 5.5 g

Answer 4

You're right. There's no problem there. The method explained clearly is as follows:

No. of moles of Mg = 6/24 = 0.25 moles

No. of moles of CO2 = (1/2)(0.25) = 0.125 moles
[Because the mole ratio of Mg to CO2 is 2:1.]

Mass of CO2 = 0.125 x (12+16+16) = 5.5g

Answer 5

My answer is also 5.5 g of CO2.
This is my working out:

There molar ratio of the reactants is
2 : 1

The atomic weight of Mg is approximately equal to 24g (ie 1 mole of mg weighs 24g).
The atomic weight of CO2 is approximately equal to 12+16x2 g ( ie 1 mole of CO2 weighs 44g).

6g Mg is 0.25 moles.
n=m/M (n=moles, m=mass of substance, M = atomic weight)
n=6/24
n=0.25 moles

Half that number is the amount of carbon required due to the 2:1 ratio.
Which is 0.125 mols (0.25/2).
Now You have to find out the weight of carbon

m=n x M
m= 0.125 x 44
m=5.5g

Answer 6

2Mg + CO2 --> 2MgO + C
I think this equation should be correct.

Now, you have 6g of Mg. You have to find the no of moles of Mg first.
no of moles of Mg
= (mass of Mg) / (relative atomic mass)
= 6 / 24
= 0.25

According to the reaction, you need 1 mole of CO2 to completely react with 2 moles of Mg. Thus, in proportion, you need 0.125 moles of CO2 to react with 0.25 moles of Mg.

no of moles of CO2 = 0.125

mass of CO2
= (no of moles of CO2) x (relative molecular mass of CO2)
= 0.125 x (12 + 2 x 16)
= 0.125 x 44
= 5.5g

Actually your method is kind of right, since I think you used the molecular mass per mole of each substance to calculate the masses 48g 44g 80g and 12g. It's just that it was sort of confusing and doesn't seem coherent, that's all. :D

Answer 7

Sorry mate,
i only specialise in alcohol and vitamin C questions

Answer 8

hydrogen gas is made

Answer 9

Dunno!