[bdawg8527]

dide most of my hw, i had a few problems i dont know how to do. Can someone help me?
1) a 2.65 sample of salmon-colored powder contains .7g of chromium , .65 g of sulfur, and 1.3 g of oxygen. The molar mass is 392.2 what is the formula of the compound?

2) A compount contains 12.8% C,2.1% H, and 85.1% Br. What is the molecular formula of this compound given that the molar mass is 188 g/mol.

3) a compound contains 10.13% C and 89.87% Cl. Determine the molecular formula given that the molar mass is 237 g/mol

4)A 7.33 g sample of lanthanum, La, combines with oxygen to give 10.29 g of lanthanum oxide. Calculate the emperical formula of this oxide.


Thx for anyone that answers these, i really appreciate it!

    * 11 minutes ago
    * - 4 days left to answer.

[Astrokel]

You have to show some work as it is against the forum rule to do your homework.

Check this out on empirical formula: http://www.google.com.sg/search?hl=en&q=calculating+empirical+formula&btnG=Search&meta=/

Once you know empirical formula, molecular formula is easy.

[Donaldson Tan]

There is a past thread on a similar problem. Use it as a guide to work out the answer for your problem. Show us your attempts and we will guide you along the way.

http://www.chemicalforums.com/index.php?topic=30695