Verified answer

4. C=92.3% H=7.8%

Assume 100 grams of compound is present. This changes percents to grams.

C=92.3g H=7.8g

Change to moles:

C=92.3 / 12.01 = 7.685

H=7.8 / 1.01 = 7.72

Divide by smallest

C=7.68 / 7.68 = 1

H=7.72 / 7.68 = 1

Empirical formula is CH

-------------

6.55x10^29 molecules HCl to moles

Divide by 6.022 x 10^23 molecules per mole to get the answer

I'm doing 1 and 3....^^

1. Molecules ---> Moles

We divide by Avogadro's # ....

6.55 x10^29 / Avogadro's #

= _______moles of HCl

3. Mass ----> Moles

First find molar mass of CuSO4 which is appr. 160g

160g of CuSO4 ----> 1 mole

1g -----> 1/160

24.5g ------> (1/160) x 24.5

= _______ moles CuSO4

Sorry bout 2, 4 and 5...I don't like %...

For #2...Find the mass of Fe2(CO3)3 which is I think appr. 292g

Find the mass of O which is 144g

(144/292) x 100/1 = _____% O2

Check it over and stuff and calculate the answer. I'm too lazy to do it -_- .....hope I help with 1-3...^^