Moles

heyy,

calcium reacts with oxygen to form calcium oxide. What mass of oxygen will react exactly with 60g of calcium?

I know the relative atomic mass of calcium is 40, and oxygen is 16, but how exactly do i use this information to find out what mass of oxygen will react exactly with 60g of calcium?

thanks for your help!

1.0M of CaO = 40g + 16g = 56g

40 / 16 = 2.5

60 / 2.5 = 24

That is how I would figure it out, so you would theoretically need 24g of oxygen to react with 60g of calcium.

EDIT- LOL, I think we'll have confused her with our different methods...

Mine and jontys the same.. I just thought best to leave her to actually work it out herself.. yours tho mate.... I don't understannnd!!

o2+2Ca=2cao
the number of moles =given mass in grams divided by the relative mass
u knw that it is o2 +2ca rit so basicall they react wid the ratio 1:1
first u find out how many moles r there in 60 grrams of ca
n=60 divided by 40 =1.5 moles
as i said b4 they react wid 1:1 ratio so
1.5 moles of oxygen will react with 1.5 moles of ca
1.5=x divided by 16=10.6666666667
so 10.6 gms of oxygen is required
hey im sure this is rit so add me to ur frnds list

I think he worked out the mass of product, so then the mass of reactants must add to give that. Never seen that method before though.

write an equation for the reaction, O2 + 2Ca ----> 2CaO (I think)

find the moles of calcium in 60g (moles = mass/Mr)

use the equation to find moles of O2 needed (in this reaction the ratio is 1:2 so divide moles of Ca by 2)

use moles of O2 to calculate mass (mass = moles x Mr)

EDIT: ask me to explain anything that didn't make sense

It's not a 1:1 ratio. It's 2:1.

2 Ca : O2

with the last step of working out the mass, do i use the relative atomic mass of just calcium of calcium and oxygen added together