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Is anyone good at chemistry

chemistry

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Oh yes, I am very good in science..
But, I do not do it now in school, I just learn it on my own

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i am having trouble doing my homework and i need help
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A sample of NH3 gas occupies 75.0 liters at STP. How many molecules is this?
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I´m out :O
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thanks anyway
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Not me :)

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I'm definitely not...

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kinda, i mixed mentos and diet coke once.

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I done that for a volcano project lol, I didn't know any other way to get it to explode
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that wont help me
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Nope. The only way I passed was the extra credit questions were about classic rock.

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Thse would be more like Geology Questions !!!
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I'm not saying that i'm good at it, but i'll try to help if i can :)

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A sample of NH3 gas occupies 75.0 liters at STP. How many molecules is this? can you help me by explaining this to me please if you are able to help me
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Use PV = nRT

P=pressure, V=volume, n=moles of gas, T=temperature, R is the gas constant which is dependent on the units of pressure, temperature and volume

R = 8.314 J K-1 mol-1 if Pressure is in kilopascals(kPa), Volume is in litres(L), Temperature is in Kelvin(K)

R = 0.0821 L atm K-1 mol-1 if Pressure is in atmospheres(atm), Volume is in litres(L), Temperature is in Kelvin(K)

find the moles first;

n(NH3) = PV / RT
= [100 kPa x 75L] / 8.314 J K-1 mol-1 x 273.15 K
= 3.302554843 moles

1 mole of NH3 is equal to 6.022 x 10^23 molecules of NH3.
So, 3.302554843 moles are equal to ;

3.302554843 moles x 6.022 x 10^23 = 1.9888 x 10^24 NH3 molecules

Hope this helped.
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not realy
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Why?
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i never learned about the STP stuff
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I'm a bit confused. :s
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sorry
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No, it's okay :)
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DrVampire is good at everything. ask her anything.

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ok so A sample of NH3 gas occupies 75.0 liters at STP. How many molecules is this? please explain this to me
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according to Avogadro's law in STP one mole of different gases have the same volume and it's 22.4 liters.
so 75.0 liters/22.4 = 3.348 moles
you know that one mole= 6.022 x 10 ^23 molecules :
3.348x6.022x10^23 =20.16 x 10 ^23
if there's any part you didn't understand just ask me.
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i have to show all my work how do i set this up
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can't you put it on here?
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No
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is there anything i can do?
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ya i will need some more help on some other problems
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then hurry up i've got 5 minutes
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never mind thank you you helped me out alot now i understand my homework
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sorry i'm a super busy student. maybe some other time :)
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