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Problem 46 Hard Difficulty

A compound with the empirical formula $\mathrm{CH}_{2} \mathrm{O}$ was found to have a molar mass between 89 and 91 g. What is the molecular formula of the compound?


$\mathrm{C}_{3} \mathrm{H}_{6} \mathrm{O}_{3}$


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Video Transcript

and this question were given the empirical formula C H 20 and asked to find the molecular formula given at the compound is a molar mass between 89 in 91 grams. So a good rule of thumb year is if we know the molar mass, we can divide that. We're sorry if we know the molar mass of the molecular formula. We can divide that by the molar mass of the empirical formula, and this will give us the whole number. If we take that whole number and we multiply it by the empirical formula, we should find a molecular formula. So let's see how this works out. First, let's find the molecular weight of C H 20 So we know carbon has a molar mass of 12.11 grams to hide regions will have a molar mass of 2.1 grams perm. Oh, and oxygen is going to be 16.0 grams per mole. So we had these old up. We'll find it. The empirical weights is around 30.0, 11 grams Permal. So we know what e. W is were also given that MW is between 89 91. So let's just take the middle ground and say it is 90 grams from no. So 90 grams Permal, divided by 30.11 grams per mole is going to come out to about three and again, molecular weights, that is empirical each. So let's go ahead and take C H 20 and multiply it all by three. So we'll have C three h six. Oh!