What is the mass?

Question

What is the mass, in grams, of 1.50 mol of iron (III) sulfate?Express your answer using three significant figures

What is the mass, in grams, of 1.30×1021 molecules of aspirin, C9H8O4?Express your answer using three significant figures.

Answer 1

Latika,

 

Iron (III) Sulfate is basically Fe2(SO4)3. The III refers to the charge on the Fe (iron) ion. Now we want to convert moles to grams so we need the molar mass which is:

2*55.85+3*32.07+12*16=111.7+96.21+192=399.91 g/mol*1.5 moles=599.865g

 

The molar mass of aspirin is:

9*12.01+8*1.008+4*16=108.09+8.064+64=124.218g/mol

 

Using Avagadro's number we can convert this to g/molecules and then multiply by number of molecules:

124.218g        1 mole

---------- X -------------------------- x 1.3x10^21 molecules (I assume this is a typo!) = .268g

mole              6.022*10^23 molecules

 

Hope that helps!