Homework Help: chemistry

Posted by jhong on Sunday, March 11, 2012 at 6:57pm.

3. Find the empirical formula for a compound that consists of aluminum and chlorine in which the aluminum is 20.2 % by mass.
4. A sample contains 71.65% CL, 24.27% C nad 4.07% H. the molecular weight is known to be 98.96 g/mol. What are the empirical and molecular formulas?

chemistry - DrBob222, Sunday, March 11, 2012 at 7:20pm
3)
Take a 100 g sample. This gives you
20.2 g Al
79.8 g O
Convert to moles.
20.2/atomic mass Al = ?
79.8/atomic mass O = ?

Now find the ratio of the two elements to each other with the smallest number being 1.00. Don't round to whole numbers too much.

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