[ohyourgodfully]

Hi, I'm really stuck on this question and would appreciate any help at all:

What is the mass (in kg) of 100 000 molecules of carbon monoxide CO?

I know the molar mass is 28.0 g/mol but I'm not sure where to go from there.

[Borek]

How many molecules in a mole?

[ohyourgodfully]

6.02×10^23

[Borek]

So - how many moles do you have?

Alternatively:

What is a mass of one molecule?

[ohyourgodfully]

That's the part I have trouble with, I realize it's a relatively simple question but I am severely dyslexic and the example questions I have that deal with these kinds of problems are completely opposite to this one and I can't work out how to get the mass from the information I am given.

[Borek]

Mass of 100 marbles is 500 grams - what is a mass of one marble?

Mass of 6.02x10²³ atoms is 28 grams - what is a mass of one atom?

[ohyourgodfully]

1 molecule = 4.65x10^-23 grams
so 100 000 molecules = 4.65x10^-18 grams = 4.65x10^-15 kg
is that right?

[Borek]

is that right?

Up to g->kg conversion (I mean - your result is correct when expressed in grams, but incorrect after unit gets converted to kg).

[ohyourgodfully]

So I'm guessing I moved the decimal to the wrong side, which would make the answer 4.65x10^-21 kg?

[Borek]

That's correct, but instead of guessing try to do it systematically, with conversion factors and correctly cancelling out units.

[ohyourgodfully]

Thank you so much for all your help Borek