<p>I need some help some chemistry that I don’t know how to do very well. I know there are plenty of chemistry nerds on this website…so if you could help me it would be highly appreciated.</p>
<li><p>A sample of NH3 gas occupies 75 litres at STP. How many molecules is this?</p></li>
<li><p>What is the mass of the sample of NH3 in problem 1?</p></li>
<li><p>How many atoms are in 1.3 X 10^22 molecules of NO2?</p></li>
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<p>For number 1 I got 1.23 X 10^28. Could anyone verify this? Thanks.</p>
<p>1.
(75 L)(1mole/22.4L)(6.02e23 molecules/1mole) - i dont have a calculator but that should give you the answers</p>
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<li><p>take the answer in #1 and multiply it by 17</p></li>
<li><p>I think you multiply 1.23 X 10^22 by 3 b/c there are 3 atoms in one molecule of NO2</p></li>
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<p>I hope this helped!</p>
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<li>a random chemistry nerd on this website</li>
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<p>i believe that you are unfortunately wrong, however my chemistry is a bit rusty so i may be wrong but.....</p>
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<li><p>At STP, there are 22.4 liters per mole of any gas. so we have 75/22.4 for the moles of NH3. then we multiply by avogrado's constant (6.02<em>10^(23)) so we then get 2.02</em>10^(24) molecules</p></li>
<li><p>For the mass we take the amount of moles and multiply by 17, the molar mass of NH3. so thats (75/22.4) * 17 which equals 56.92g</p></li>
<li><p>There are three atoms per molecule so 1.3 * 10^(22) * 3 is equal to 3.9 * 10^(29) atoms. </p></li>
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<p>once again check my methods with someone else, my chemistry is a bit rusty.</p>
<p>okay. just use PV=nRT for the first one.
P = 1 atm
T= 298K
R=.0831
n = PV/RT
n = 75/(.0831 * 298)
n = 3.03 moles NH3
multiply that by 6.02E23 = 1.82 E 24 molecules of NH3.</p>
<p>for #2, take the 3.03 moles of NH3 and multiply it by 17, the molar mass of NH3. 3.03 * 17 = 51.51 g NH3.</p>
<p>for #3, 1.3E22 x 3(the number of atoms in one molecule of NO2) = 3.9E22 atoms.</p>