# When one mole of ammonia is heated to a given temperature, 50% of the compound dissociates and the following equilibrium is establised.

NH3(g) <-> 1/2N2(g) + 3/2H2(g)

(note: <-> is my sad attempt at the equilibrium symbol)

What is the total number of moles of gas present in this equilibrium mixture?

A 1.5
B 2.0
C 2.5
D 3.0

I'm thinking it's D, but I'm asking to check if it's as easy as adding everything up

As always, thanks for your help!

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## You're ok with that symbol. the - sign works a little better than the underline, like this <-> but usually I do <--> or <==> or <->.

Yes, it's as easy as adding everything BUT you must be careful what you add. The 50% dissociation means that NH3 is only 0.5 at equilibrium and the others change also. I is initial, c is change, E is equilibrium. The ICE chart method will solve a lot of chemistry problems if you get into the habit of thinking that way.
........NH3 ==> 1/2N2 + 3/2 H2
I......1mol......0.......0
C.....-0.5......0.25...0.75
E.....0.5......0.25.....0.75

Total = not D

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In this equilibrium, one mole of ammonia (NH3) dissociates into 1/2 mole of nitrogen gas (N2) and 3/2 moles of hydrogen gas (H2).

So, initially, we have 1 mole of NH3, and when it dissociates, we get 1/2 mole of N2 and 3/2 moles of H2.

Adding them all up, we get 1 mole (NH3) + 1/2 mole (N2) + 3/2 moles (H2) = 2 moles.

So, the total number of moles of gas present in the equilibrium mixture is 2.0.

Therefore, the correct answer is B) 2.0. You got it!

Hope that helped, and don't hesitate to reach out if you have any more questions!

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## To determine the total number of moles of gas present in the equilibrium mixture, we need to consider both the reactants and the products in the equation.

From the given equation, we can see that one mole of ammonia (NH3) dissociates to form 1/2 mole of nitrogen gas (N2) and 3/2 moles of hydrogen gas (H2).

Since only 50% of the ammonia dissociates, we can calculate the moles of reactants and products as follows:

Reactants:
- Ammonia (NH3): 1 mole (initial amount)
- Nitrogen gas (N2): 1/2 mole (formed from the dissociation of ammonia)
- Hydrogen gas (H2): 3/2 moles (formed from the dissociation of ammonia)

Total moles of reactants = 1 moles (NH3) + 1/2 mole (N2) + 3/2 mole (H2) = 3 moles

Thus, the correct answer is D) 3.0 moles.

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## To find the total number of moles of gas present in the equilibrium mixture, you need to consider the stoichiometry of the reaction. The balanced equation tells us that one molecule of NH3 will produce 1/2 molecule of N2 and 3/2 molecules of H2.

Given that 50% of NH3 dissociates, we can assume that if we started with one mole of NH3, 0.5 moles of NH3 will dissociate to form 0.25 moles of N2 and 0.75 moles of H2.

To find the total number of moles of gas present, you need to sum the moles of each species. In this case, it would be 0.25 moles of N2 + 0.75 moles of H2 + 0.5 moles of undissociated NH3.

Adding these values together, we get:

0.25 + 0.75 + 0.5 = 1.5 moles

Therefore, the correct answer is option A, 1.5 moles.