Determine the empirical and molecular formulas of each of the following substances: (c) Epinephrine (adrenaline), a hormone secreted into the bloodstream in times of danger or stress, contains 59.0% C, 7.1% H, 26.2% O, and 7.7% N by mass; its molar mass is about 180 u.

Video transcript

Hey everyone. So here we ask, calculate the empirical molecular formula of loose scene, which has a molar mass of 131.17 g per mole and has a mass percent composition of 54.94% carbon 9.99% hydrogen 10.68% nitrogen in 24.39% oxygen. And we know that the empirical formula gonna give us the relative number of atoms in the molecular formula can give us the actual number of atoms. So we're gonna assume we have 100 g of the compound and now we can convert our percentages into grams. The 54th 0.94 grams of carbon 9.99. And supplies region 10. grams of nitrogen in 24.39 grams of oxygen. And now we're going to convert the masses of each into malls using the molar masses for one ball of carbon. We have 12.11 g of carbon. When we get 4.57 malls in one mold of hydrogen have 1.8 g. And we get 9.91 malls in one more of nitrogen, we have 14 0.7 g. We're going to get 0.76 malls in one more of oxygen. 15 0.999 grams. We're going to get 1.52 malls. So now we need to divide each by the smallest number of moles to get the small toll number ratios over carbon, we have 4.57 by 0.76. We're going to get six for hydrogen with 9.910 point 76. We're gonna get 13 for nitrogen 0.76 divided by 0.76. To give us one and for oxygen you have 1.52 by 0.76. Would you give us two? Our empirical formula? We're gonna have C six age 13 in 02. Now we need to figure out what numbers multiply the subscript by to get the whole number ratios for the molecular formula. They're going to do this by using the formula X. It was a Mueller mass. What about the empirical mass? Our empirical mass or C six? Age 13 in is six. 12.11 g plus 13 times 1.8 g plus 14.7 g plus two times 15.999 g. And it's gonna give us 100 30. 1 0.17 g. We're gonna have eggs equals 100 31.17. About 131.17 which is one. So now we need to multiply the subscript and empirical formula by one. Our molecular formula. It's gonna be the same as an empirical formula. They're going to have C six age 13 N. 02. Thanks for watching my video and I hope it was helpful