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Problem 91 Hard Difficulty

Calculate the mass in grams of each of the following samples.
a. $10,000,000,000$ nitrogen molecules
b. $2.49 \times 10^{20}$ carbon dioxide molecules
c. 7.0983 moles of sodium chloride
d. $9.012 \times 10^{-6}$ moles of $1,2$ -dichloroethane, $\mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}$

Answer

A.$4.653 \times 10^{-13} \mathrm{g} \mathrm{N}_{2}$
B.$1.82 \times 10^{-2} \mathrm{gCO}_{2}$
C.$4.148 \times 10^{2} \mathrm{g} \mathrm{NaCl}$
D.$8.918 \times 10^{-4} \mathrm{g} \mathrm{C}_{2} \mathrm{H}_{4} \mathrm{Cl}_{2}$

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Top Chemistry 101 Educators
Stephanie C.

University of Central Florida

Lizabeth T.

Numerade Educator

Stephen P.

Drexel University

JH
Jacquelin H.

Brown University

Video Transcript

Okay, So in this video, we're trying to find the mass of both compounds given, like number of molecules. Okay, so what do we know? That the patient for mass as it was in France. We know that mass is equivalent to moles multiplied by Moeller masts. But here we have nitrogen gaps. When you're given 1.1 times 10 to the exponents turn molecules, a mention gas, and we need to find the massive that so we can't work with moles. Let's try a fighter them to substitute moles. So we know that moles is equivalent to number of molecules. Number of molecules over at big are Joe's constant on the A, you know, the 6.22 times 10 to the 23 because of you know that moles is equivalent to number. Molecules want supplied by a guard, just constant and a So we just have to, you know, substitute this in and we get that mass is equivalent truth. Number of molecules. Hundreds called this molecule times Moeller mass divided by I'm a god Rose constant. So, yeah, we just substituted this equation into this equation here to get back. All right, so that makes everything straightforward. So then we just take our number of molecules divided by have a god just constant 6.0, to to times tend to the 23 and e represents times tend to the exponents. I hear the explosion 23. I take a and we multiply it by him. The morning after that, you gas, which is just 28 when? Zero 14 approximately grams per mole. Okay, so Alec are Joe's number is in units of Perm ALS. So we have most in the denominator of the denominator and the denominator of the denominator is the nucleus. I mean, up nucleus, the numerator. So, yeah, we have cancellations going here on your we just put the those most appear. Yes, the average got juice number and Permal, which would be up there. Liberator molecules is not a unit that are left with this mass. So this gives us 1.66 times 10 to the negative 14. Oops. Remember, actually, this gives us for 0.65 I was most 4.65 times 10 to the negative. 13 Gramps. Okay, so here we took number of molecules and found mass let's do the same thing here with carbon dioxide. So this is again molecules. Molecules is also out of units. I'm not gonna write it out again. We divide this by of a garden hose, constant and a I multiply it by the molar mass of carbon dioxide which we can find by summing up the atomic masses of each Adam bound to the product table. And this basically gives us 44 grams per mole. And then this will equal zero that Zira 0.0 18 to Gramps. So, you know, quit tomorrow. And I feel this exercise really helps us contextualized and understand. Like how you know how small atoms are are molecules are three can have up to 10 to the 10 molecules and still have such a next, really negligible Masso and have even greater Lee Tim E to the 10 2 times 10 to the 20 and still being negligible. It's quite interesting. So now here we're working with moles. We have a particular mole of salts and a c l. So in chlorate and a particular most of this organic compound You sure it's dyke oro ethane. Okay, so sorry, Rob. But but Yet here we have moles off our particular compounds and we're gonna find mass. So we'll just use this formula over here and take moles. Multiply that been Muller maps. Okay, so the molar mass of san chloride is 58 points for four grams per mole. That was a very clear unit cancellation. Here. Just get on top, Mulls over moles, cancels out basically equal to one, and we're left with grams on top. And this gives us floor 114 points. Eight, Gramps. So here you can see that a mole of something is a lot of something. A lot of a component here to hear for dickler ethane or C two h four seal to thank you. The organic chemistry. Have we just count up the atomic masses of each element? And we find that the molar mass is 98.9 states grams per mole. All right? And that, you know, look proper. My equals equates to eight points. Mine too. Times 10 to the negative four grams. And remember, uh, something to explain it of negative number just means it's super small now that it's negative

McMaster University
Top Chemistry 101 Educators
Stephanie C.

University of Central Florida

Lizabeth T.

Numerade Educator

Stephen P.

Drexel University

JH
Jacquelin H.

Brown University