What is the empirical formula of a compound that is 85.6% carbon and 14.4% hydrogen by weight?

1) since we have percentages, we can assume we have 100 grams of the compound.

85.6% Carbon---> 85.6 grams of C
14.4% Hydrogen--> 14.4 grams of H

2) we need to convert the grams to moles for each one using their molar masses. 

molar mass of C= 12.0 g/mol
molar mass of H= 1.01 g/mol





3) divide each mole by the smallest value(7.13) to find the ratios

Carbon---> 
Hydrogen---> 

4) use these ratios to write the empirical formula.

CH₂

Determine the  wavelength of light emitted when an electron  in an li2+ ion  makes a transition from an orbital with n  =  6 to an orbital with n  = 5.

They can measure  the amount of energy gained or lost