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Ch.2 - Atoms, Molecules, and Ions

Chapter 2, Problem 2b

The following diagram is a representation of 20 atoms of a fictitious element, which we will call nevadium (Nv). The red spheres are 293Nv, and the blue spheres are 295Nv. (b) If the mass of 293Nv is 293.15 u and that of 295Nv is 295.15 u, what is the atomic weight of Nv?

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Hi everyone. This problem reads below is an image showing 30 atoms of a hypothetical element az the blue spheres correspond to Az with a mass of 190.3 units. Meanwhile the green spheres correspond to 193 A Z. With a mass of 193.4 units, calculate the atomic mass of AZ. So in order for us to calculate the atomic mass, we're going to need to know the relative abundance of both 198 and 193. And once we have those relative abundances we can multiply them by their mass units to get the atomic total mass. So let's go ahead and start there. So for our relative abundance I'll initial that as our a for 190 A Z. We know that's represented by the blue spheres. And so we have 22 blue spheres out of 30 total. Okay. And we're going to multiply that by 100. So our relative abundance for the 1 90 Az is 73.3%. So let's go ahead and do the same thing for R 93 az. Okay. We're going to calculate its relative abundance and we have eight green spheres out of 30 total and we're going to multiply this by 100 And that gives us 26.67%. Okay, Let me rewrite that. So it's a little clearer. 26.67%. So now that we know the relative abundance of each, we can calculate the atomic mass. Okay. And we're going to calculate the atomic mass by taking the relative abundance and multiplying it by its mass units. So for our 1 90 az our relative abundance as a decimal is 0. times its units. Its mass units is 190. units. And this is going to be added to our 1 Az we know its mass percent is a relative abundance is 0.2267 times its unit mass units is 100 and 93.4 units. Okay, so in total we get 191. Units and this is going to be our atomic mass. So let me write that a little clearer. I apologize. So we get .23 units. And this is going to be our final answer. We'll move this to the side. So there we go. That's it for this problem. I hope this was helpful