Question

Calculate the number of grams of nitrogen gas required to make 1.22 L of ammonia at STP

Answer 1

Use the Ideal Gas Equation: PV = nRT; where 'n' is the amount of moles of ammonia, 'R' is the gas constant.

Answer 2

At STP, P = 1 atmosphere and T = 293 Kelvin

Answer 3

We wants to find how many moles of ammonia are in 1.22 L at STP, for this first step.

Answer 4

so how would you find ammonia? i'm sorry but i am just terrible at chemistry

Answer 5

We plug in the numbers we got so far.

Answer 6

\[(1 atm)(1.22 L) = n*(0.08206 \frac{L-atm}{mol-K})(293 K)\]

Answer 7

R is a gas constant, so it never changes. Solve for 'n', that'll be the amount of moles of ammonia.

Answer 8

ok

Answer 9

can you cross out K because when you solve for "n", you can divide potassium by itself and they cancel out. would that be correct?

Answer 10

Err, that K means Kelvin. And yes, all the units should be crossed out, except 'moles'.

Answer 11

oh wait... not potassium, it would be the Kelvins

Answer 12

(1atm)(I.22L)= n(24.04358L-atm/mol) is what i have so far.

Answer 13

Ok, now solve for n. It took you like 10 minutes to multiply?

Answer 14

no the atm and the mol was confusing me so i just started over and checked what i had already to make sure i was doing it right

Answer 15

The Liters and atmospheres units cancelled out when you divide.

Answer 16

so n= .o507411mols?

Answer 17

Not sure, lol. didn't do the math, hold on.

Answer 18

lol ok

Answer 19

Yes, so we have 0.0507 moles of ammonia, NH3. Can you use stoichiometry to figure out how many moles of Nitrogen, N, are in the ammonia?

Answer 20

i think so

Answer 21

Ok, we have 0.0507 moles of NH3. How many moles of N are there in it?

Answer 22

wouldn't there be 28g of moles in nitrogen?

Answer 23

Err, what? The molar mass of Nitrogen is 14 grams per mol.

Answer 24

We're not there yet. Did you find how many moles of nitrogen there are?

Answer 25

how did you get 14?

Answer 26

It's from the periodic table lol.

Answer 27

oh hehe lol

Answer 28

An atom of nitrogen weights 14 Daltons, a mole of nitrogen measures 14 grams.

Answer 29

in NH3, there is only one atom of nitrogen so would that make the mole of nitrogen in NH3 only 14?

Answer 30

Ehh, no, take it back. We got 0.0507 moles of NH3. For every mole of NH3, there is 1 mole of N, nitrogen. We get that from the molecular formula. So...
\[(0.0507 mol NH_3)(\frac{1 mol N}{1 mol NH_3}) = 0.0507 mol N\]

Answer 31

Now, we have 0.0507 moles of N. We can now use the molar mass of N to figure out the mass.

Answer 32

alright so we just solve for N?

Answer 33

No, sorry lol. N means nitrogen.

Answer 34

I was trying to label both NH3 and N.

Answer 35

We multiply the 0.0507 moles of N by the molar mass to get the grams of nitrogen.

Answer 36

0.7098 grams of nitrogen

Answer 37

Correct.

Answer 38

awesome! thx!! so is that the answer?

Answer 39

i gtg but thx for helping me so much.