Year 12s: what will be the first way you research your future options? >>

moles > grams

Im pretty stumped on this one,

what is the mass of

a) 0.02 mol of octane c8h18

can someone give me a hint on how id solve this? does mass basically mean mass in grams?

Reply 1

LearningMath

Yes, find the mass of 1 mole of octane, then divide by 50.

You flop.

0.02 mol of octane c8h18

n = mass / Molar mass
0.02 = mass / [(12x8)+18]

therefore mass =
0.02 x [(12x8) + 18]

Correct me if I'm wrong.

Reply 4

Edamame

strawberry

0.02 mol of octane c8h18

n = mass x Molar mass
0.02 = mass x [(12x8)+18]

therefore mass =
____0.02____
[(12x8) + 18]

Correct me if I'm wrong.

How can n = mass x molar mass??

You are implying the units mol = g x g/mol = g^2/mol ??

Reply 5

Owly-woes

strawberry

0.02 mol of octane c8h18

n = mass x Molar mass
0.02 = mass x [(12x8)+18]

therefore mass =
____0.02____
[(12x8) + 18]

Correct me if I'm wrong.

You are wrong... the formula you wanna use is mass = mol x Molar mass
So you have:
m = 0.02 mol x ((8 x 12) + (18 x 1.008) g/mol
moles cancel out and you are left with grams...

The answer is, therefore, 2.28288 grams.