Chemistry help please...Urgent!

Question

Typical household ammonia solution has a concentration of 1.24 mol L-1. What volume of this solution would contain 0.500 mol of NH3?

In a solution containing Fe2(SO4)3, the concentration of the sulfate ions was 0.55 M. What is the concentration of the Fe2(SO4)3?

A 1.5 L bottle of soft-drink contains 0.075 g of calcium, present as calcium ions. What is the concentration of calcium in mg L-1?

please any help will be greatly appreciated..

Answer 1

1.24 mol in 1000 cm3,

1.00 mol in 1000/1.24 cm3.

0.50 mol in [1000/1.24] * 0.5 cm3,

Ans = 403 cm3 NH3.

Answer 2

Did you hear the one about the chicken whose mother laid an orange? She cried " Oh, look what Mama laid". OK, if you read my previous answer you should be able to do this one in your sleep. Anyway here are the answers

1000 ml contains 1.24 mol. 0.5 x 1000/1.24 = 403 ml

0.55/3 = 0.183M (Each mole Fe2(SO4)3 provides 3 sulfate ions)

1.5 L contains 75 mg. 1L contains 50 mg. 50mgL^-1