chemistry problem please help?

Question

1.) An organic compound is analyzed and found to be carbon 51.90%, hydrogen 9.80%, and chlorine 38.30%. what is the empirical formula of this compound?




2.) A sample of oxygen gas, O2, weighs 28.4 grams. How many molecuiles of O2 and how many atoms of O are present in this sample?

Bobby · Accepted Answer

if we have 100g of compound we wouls have 51.90 g of c 
= 51.90 / 12 moles of C = 4.325 moles

moles of H in 100 g of compound = 9.80 g or 9.80 moles of H 

moles of Cl = 38.50 / 35.5 = 1.085 molesof Cl

molar ratio of C:H:Cl = 4.325:	9.8:	1.085
divide by the smallest number and we have 4:9:1

empirical formula is C4H9Cl ... 

moles of O2 in 28.4g = 28.4 / 32 = 0.8875 moles of O2 

there are 6.02 x 10 ^23 molecules of O2 in 1 mole of O2 so we have 

0.8875 x 6.02 x 10 ^23 molecules = 5.343 x 10 ^ 23 molecules of O2

number of O atoms =  5.343 x 10 ^ 23 x 2 = 10.69 x 10 ^23 atoms of O

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chemistry problem please help?

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