Determine the molecular formula of a gaseous compound that is ...

Question

Determine the molecular formula of a gaseous compound that is 49.48% carbon, 5.19% hydrogen, 28.85% nitrogen, and 16.48% oxygen. At 27°C, the density of the gas is 1.5535 g/L and it exerts a pressure of 0.092 atm.

Accepted Answer

So here we are asked to determine the molecular formula of a gaseous compound that is 49.40% carbon, 5.19% hydrogen and 28.85% nitrogen and 16.40% oxygen. All right, so at 27 degrees Celsius, the density of the gas is 1.5535 g per leader, and it exerts a pressure off 0.92 atmospheres. All right, we know that they're giving us Gramps here because if you look, all of this adds up to 100% and we usually assume that this is out of 100 g so automatically we can convert all of those percentages into grams. This is reminiscent of empirical formula and in a molecular formula. If you haven't watched those videos, I highly suggest you go back and take a look because a lot of what we're gonna do initially is based on the steps we've learned when calculating empirical formula and molecular formula. So when dealing with empirical formula, each of these elements are in their mono atomic forms. So here we have 5.19 g h 28.85 g n and 16.48 g Oxygen. What we're gonna do next is we have to convert all of these grams into moles. So we're gonna divide them all by their atomic masses, which you find on the periodic table. So one mole of C one mole of H one mole of N one mole off. Oh, there are atomic masses I'm getting from the periodic table, people. No, Here we're going to cancel out all the grams and we'll have the moles of each. So when we do that, we're gonna get as our moles. For each 4.1199 moles of C 5.1488 Moles of H 1.296 Moles of n and finally 1.33 or 1.300 Moles of O. Next step is we divide all the mole answers that we just got by the smallest more answer. So the smallest answer we got from moles were the moles of nitrogen. So all of them get divided by that number. So here, when we divide each of them by that number, what do we get We're gonna get here. Four carbons, five hydrogen, one nitrogen and one oxygen. This will give us our empirical formula. So our empirical formula here will be C four h five and oh, now to determine the molecular formula, remember to determine molecular formula. Gonna say molecular formula equals the n factor times your empirical formula. Now remember, your end factor is not the same as your end, which stands for moles when dealing with the ideal gas law. So here, we're going to figure out, are we have our empirical formula. We need to figure out what are, in fact, er is and factor equals the Moller Mass off our gas divided by the empirical mass. Okay, so here we're going to say that the empirical mass comes from the empirical formula where we add up the four carbons, the five hydrogen, the one nitrogen and the one oxygen. When you add the ball up together, that gives you 83 09 g per mold. And how exactly do we determine the Mueller Mass? Well, remember, we're dealing with density here of a gas. Mueller mass equals d rt. Over peak, the density of the gas times are our constant. Yeah, times are temperature in Kelvin. So we add to 73 15 to this to give us 300.15 Kelvin divided by our pressure in atmospheres here. When you do that, you should get your motor mass. Ask 4 15.90 g per mole. So n factor here would equal five Now that we have the in fact and we take that in factor and plug it in here. So that means that our empirical formula, all the elements within it are gonna increase fivefold. So we have C 20 h and 55 So this year would represent the molecular formula off are unknown gas.

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