Citric acid, the compound responsible for the sour taste of lemons, has the following elemental composition: C, 37.51%; H, 4.20%; O, 58.29%. Calculate the empirical formula of citric acid.
so i did that and got C6H8O7 but now i need to find the molecular formula and i know you have to find 'n' by dividing the mass of the compound by the mass of the empirical formula.
so the mall of the ef is 192g. they didn't give me a mass of the compound so should i assume its 100g??
i did that and get 'n' to be like .5 but you can't multiply the ef by .5 to get the molecular formula because 'n' has to be a whole number right??
what am i doing wrong?
2 answers
No, assuming the mass is 100 g is not the way to go. You MUST have some more information in the problem. One way is to give information for elevation of boiling point or depression of freezing point to determine the molar mass of the compound. For gases the problem often gives density; of course this is not a gas. What other information is given in the problem?
What does mall of the ef mean? That's the information you need.
192/192 = 1 so n = 1
192/192 = 1 so n = 1