a. Take a 100 g sample which gives you
85.63 g C and
14.37 g H.
Convert to mols.
85.63/12 = ?
14.37/1 = ?
Now find the ratio of C to H with the smaller number being 1.0 and round to whole numbers. This gives you the empirical formula.
b. Use PV = nRT and solve for n = number of mols. Then mol = grams/molar mass. You know mols and grams, solve for molar mass. )As an alternative, 22.4 L at STP will be 1 mol of the gas)
c. Calculate the empirical formula mass. It will be CxHy where x and y are the subscripts for the formula. Find the empirical formula mass. Then
(empirical formula)z = molar mass where z represents the number of formula units in the molecular formula. Round to a whole number for the molecular formula. Post your work if you get stuck.
A gaseous hydrogen and carbon containing compound is decomposed and found to contain 85.63% C and 14.37% H by mass. The mass of 258 mL of the gas, measured at STP, was found to be 0.646 g.What is the molecular formula of the compound?
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1 answer