]How many atoms of cobalt would there be in a 2.2-gram sample of cobalt?

4.64 x 10^21 atoms

2.25 x 10^22 atoms

1.61 x 10^25 atoms

7.81 x 10^25 atoms

Question

]How many atoms of cobalt would there be in a 2.2-gram sample of cobalt?

4.64 x 10^21 atoms

2.25 x 10^22 atoms
		
1.61 x 10^25 atoms
		
7.81 x 10^25 atoms

anonymous · Answer

Help PLEASE !!!! :(

wolfe8 · Answer

Welcome to OpenStudy. Don't worry, I will try to help you. First, can you find the number of mole of cobalt you have?

anonymous · Answer

idk how to find the mole?

wolfe8 · Answer

This should help: http://erhs.rcsnc.org/UserFiles/Servers/Server_4766394/Image/Donna%20Scofield/mole%20conversion%20map.bmp

wolfe8 · Answer

To navigate on that chart, note that to go from grams to moles, you have to divide by the molar mass.

anonymous · Answer

So it would be 1.61x10^25 ?

anonymous · Answer

help please :((((

wolfe8 · Answer

Can you show me what you did? Do you know what the molar mass is for cobalt? This will help: http://www.ptable.com/

anonymous · Answer

molar mass is 59 ?

anonymous · Answer

to be exact its 58.93

wolfe8 · Answer

Yes :) So you divide 2.2 by 58.93 to get the number of moles. Then you multiply it by the Avogadro's number given in the chart at the top.

anonymous · Answer

I don't see where the Avogadro's number is?

wolfe8 · Answer

Ah it's not labeled that way in the chart. It is 6.02*10^23. It basically means the number of atoms/molecules in one mole of a substance

anonymous · Answer

oh okay, let me do the math then

wolfe8 · Answer

Sure thing.

anonymous · Answer

so it would be 6.02x10^23 times 26.78?

wolfe8 · Answer

26.78 is not the number of moles I get. Show me how you got that please

anonymous · Answer

I divided 58.93/2.2

wolfe8 · Answer

It's the other way around hehe. Molar mass means how heavy 1 mol of the substance is.

anonymous · Answer

ohhhhh ok

anonymous · Answer

3.7x10^2 ?

wolfe8 · Answer

Yup. And you multiply that with Avogadro's number.

anonymous · Answer

Ok thx

anonymous · Answer

do I add the exponents? or multiply them?

wolfe8 · Answer

I believe you add them since you are multiplying the indices.

anonymous · Answer

Ok Perfect thanks!!

wolfe8 · Answer

You're welcome. All the best. Do take time to read our CoC: http://openstudy.com/code-of-conduct And if you're satisfied with my response, you can give me a medal and close this question. :)