Question

PLEASE HELP . ill give a medal out to whoever helps me What is the mass, in grams, of a sample of 7.83 × 1024 atoms of helium (He)? Show your work or explain the steps that you used to determine your answer.

Answer 1

its 10^24 btw

Answer 2

We were given atoms of He and we are looking for grams. Conversion factors that will be helpful are 6.022x10^23 atoms = 1 mol and 1 mol of He = 4.026 g.

Answer 3

Take what you were given, first convert it into moles, then convert it into mass. Make sense?

Answer 4

No :/ im sorry i wasnt there for the lesson so im all confused with my hw

Answer 5

I'll work this one as an example, then. You start with 7.83 x 10^24 atoms of He. Multiply by the fraction (1 mol He/6.022x10^23 atoms). Since these quantities are equal, you are essentially multiplying by 1. That way you can change the unit without chaning the value. Following me so far?

Answer 6

*changing

Answer 7

YEs :)

Answer 8

That gives you 13 moles of He.

Answer 9

Now you can take those 13 moles of He and use the molar mass of He to convert to grams. 13 moles He *(4.0026 grams He/1 mol He)= 52.0 g He

Answer 10

and thats it :o ?

Answer 11

That's it. You were looking for mass, and we found it. :)

Answer 12

Aw ok thank you so much :) that was very easy!

Answer 13

Great! No worries. :)