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# Calculate the molecular mass (in amu) of each of the following substances: (a) $\mathrm{CH}_{3} \mathrm{Cl},$ (b) $\mathrm{N}_{2} \mathrm{O}_{4},$ (c) $\mathrm{SO}_{2},$ (d) $\mathrm{C}_{6} \mathrm{H}_{12},$ (e) $\mathrm{H}_{2} \mathrm{O}_{2}$(f) $\mathrm{C}_{12} \mathrm{H}_{22} \mathrm{O}_{11},(\mathrm{g}) \mathrm{NH}_{3}$.

## (a) 50.49 amu.(b) 92.01 amu.(c) 64.07 amu.(d) 84.16 amu.(e) 34.02 amu. (f) 342.3 amu. (g) 17.03 amu.

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##### Allea C.

University of Maryland - University College

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### Video Transcript

So for this problem, we're told to calculate the molecular mass in atomic mass units for each the following substances. And so our approach is we're just gonna add each of the molecular masses for each element and multiplied by how many there are to find the overall molecular mass for each compound. The 1st 1 we have C H three feels so we just need to find the atomic math units for each of them. So we know that the molecular mass of one atom of carbon his 12 point well one then we have three hydrogen, so we just multiply like 1.8 And then finally we have Corinne, which is 35.45 and then he add those all up we get 50 0.49 a m u part B for part B. We have nt or for so we just need to times you molecular massive nitrogen. But she's 14 for no one times forward of the molecular mass of oxygen, which is 16 points year zero and any Abbott all together you get 92 point out to you. Part C part C assets for us or to So now We just need the atomic mass of sulphur, which is 32.7 and two times oxygen, which is 16. And when you add those together you get 64 10 70 you party party is C six, age 12. So we need six carbons. Just 12.1 and 12 5 regions. Just 1.8 And when you add all those together, you get that The atomic mass is 54. We're not 54 84 point 16 You party party, we have H 202 So that would just be too hydrogen, which is one point Hello. Eat plus two oxygen's, which is 16 0.0, and then when you add all those together you get 34 point Chilean part F See 12 age 22 11. So this is a bit bigger, but we just use the same approach. 12 carbon put for no one 22 hydrogen 1.0 H in 11 oxygen. But you're 16 point. Oh, and then when you plug all that on your calculator, you will get 300 42 0.30 you. And in the last part we have part G, which is NH three. So we just take the aim. You of nitrogen? 14 point, though. Three of hydrogen we had those all together we get 17.3 a m. So those were the final answers for all the parts.

##### Allea C.

University of Maryland - University College

Lectures

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