Chemistry questions - help!

[RyanJ]

Hi everyone.

 

I'm a but stuck on two questions and have no idea how to approach them as my teacher has never covered them!

 

What amount of each substance is contained in the following:

 

b) [math]1.00 * 10^{22}[/math] atoms of Cu

 

 

3) The mass of one molecule of a compound is [math]2.19 * 1^{-22}g[/math]. What is the molar mass of the compound?

 

Any help appreciated

 

Cheers,

 

Ryan Jones

 

Edit: Sorry for the double post - somethign wierd happened while I was posting...

[The Thing]

b) What AMOUNT? Now, what unit is THAT? Mol or grams or what?

Assuming it's moles:

[math]

1.00*10^{22}atoms * \frac{1 mol}{6.022*10^{23}atoms}=1.66*10^{-02}mol

[/math]

Assuming it's grams:

[math]

1.00*10^{22}atoms * \frac{63.546g}{6.022*10^{23}atoms}=1.06g

[/math]

 

3)I DO hope you mean 2.19*10^-22g.

[math]

\frac{2.19*10^{-22}g}{1 molecule}*\frac{6.022*10^{23} molecules}{1 mol}=131.88g/mol

[/math]

[RyanJ]

Thanks The Thing, that was exactly what I was looking for

 

Cheers,

 

Ryan Jones