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In this video, we're going to explain how to calculate the enthalpy change of ammonia.
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And we're using a double bonded nitrogen, double bonded hydrogen, in order to form ammonia as well.
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And so it helps to have the balanced equation first.
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So if we have nitrogen plus hydrogen, that's going to form ammonia, nh3, excuse me, there.
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And we need to actually have a balanced equation.
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So if we look at the balanced equation, we have two nitrogen on the left, only one on the right.
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We have two hydrogens on the left, three on the right.
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So we need to balance this out and we'll do the hydrogens first.
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I'm going to multiply this whole thing.
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I have two hydrogens over there, three here.
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So i'm going to make this six and also make this one six by putting a three in front.
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And what that does is in the process balances out my nitrogen so that i have two on each side.
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Now, if we're using recommended numbers of enthalpy for a nitrogen double bond, or actually sorry, it's a nitrogen triple bond to be in actuality, we have 945 kilojoules per mole for that double bond or triple bond, i should say.
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The hydrogen, we have 436 kilojoules of energy, but we have to remember that there's actually three of them there.
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And then for each nitrogen to hydrogen bond, we have 391 kilojoules, but in reality, there's three nitrogen to hydrogen bonds here, but there's a nitrogen to hydrogen bonds here.
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But there's a total of six because we have to multiply the whole thing by two.
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So if we're going to multiply this by six, what we have to remember as well is that typically to break bonds, that's usually a generally energy -intensive process, that energy has to go in.
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And therefore, these would be additional or positive values.
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But when bonds are formed, we're usually going to be releasing energy.
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When new materials are formed, they actually become more stable because they release the energy.
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So these ones that we start within our reactants are going to be positive values.
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This one really should be a negative value.
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And so when we look at this, obviously there's only one here...