# Moles

Announcements
#1
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?

0
12 years ago
#2
(Original post by abey_27)
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?

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
0
12 years ago
#3
2Ca + 02 >>>>>> 2Cao

Moles = Mass/Mr

Moles of Calcium = 60/40 = 1.5

Ratio = 2:1

Moles of O2 = 0.75

Mass = Mr x Moles = 0.75 x 32 = 24g
2
12 years ago
#4
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...
1
12 years ago
#5
(Original post by Zedd)
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!!
0
12 years ago
#6
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
1
12 years ago
#7
(Original post by rainbowbex)
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!!
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.
0
12 years ago
#8
(Original post by Nren)
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
It's not a 1:1 ratio. It's 2:1.

2 Ca : O2
0
12 years ago
#9
(Original post by Jonty99)
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.
My boss says I'm special It might be that I've developed a backwards method from my work, I do analysis so I tend to have to work back and find out why something is wrong.
0
3 years ago
#10
(Original post by rainbowbex)
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
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
0
3 years ago
#11
(Original post by wer343lit)
It's not a 1:1 ratio. It's 2:1.

2 Ca : O2
True dat
0
3 years ago
#12
(Original post by maisiemets)
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
while finding mass of O2 , use Mr of O2
0
X

new posts
Back
to top
Latest

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### Poll

Join the discussion

#### Do you know what you'll do if you don't get the grades you're hoping for?

Find something else in clearing (30)
28.85%
Take a gap year (16)
15.38%
Resit my exams (28)
26.92%
Look for alternate pathways to the career I want (15)
14.42%
I don't know yet (10)
9.62%
Something else (tell us in the thread) (5)
4.81%