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Ch 18: Thermal Properties of Matter

Chapter 18, Problem 18

How many moles are in a 1.00-kg bottle of water? How many molecules? The molar mass of water is 18.0 g/mol

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welcome back everybody. We are given that we have 10 kg of di atomic nitrogen inside a cylinder. We are also told that the molar mass of this. Di atomic nitrogen is 28 g per mole and we are tasked with finding two separate things here. We are tasked first with finding the number of moles of di atomic nitrogen. And then we are also tasked with finding the number of molecules of the di atomic nitrogen inside of the container. Let's go ahead and start with part one here. The number of moles. The formula ford is simply just going to be the mass that we are presented with divided by the molar mass. So let's just go ahead and plug in those numbers. We are told that there's 10 kg of di atomic nitrogen inside of the cylinder and then the molar mass is g per mole. But we need to work in kilograms. So I'm gonna multiply this by 10 to the negative third, giving us kilograms per mole. Which when you plug this into your calculator, you get that We have 3.6 times 10 to the second power moles of di atomic nitrogen. Right now, moving on to part two here, we need to find the number of molecules in the container. While the formula for this is simply the number of moles that we have times of a God rose number. So let's go ahead and plug in our numbers there in the number of moles. We just found to be 3.6 times 10 to the second avocados number, of course is six point oh 22 times 10 to the 23rd. And when you plug this into your calculator, you get an answer of 2.15 times 10 to the 26 molecules. So now we have found both the number of moles and the number of molecules, and these two answers correspond to answer choice B. Thank you all so much for watching. Hope this video helped. We will see you all in the next one.
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