00:01
So for this question, we're trying to find the change in entropy of the surroundings.
00:06
So the equation that we're going to use to solve for the change in entropy is that the change in entropy of the surroundings is equal to negative the change in enthalpy of the system divided by t, the temperature.
00:25
So in purple, i've put the change in enthalpy of formation for all of the parts of the reaction.
00:35
So from the change in enthalpy of formation, we can calculate the change in enthalpy of reaction, which will tell us the amount of heat released per mole of the reaction.
00:48
Then we'll use that 2 .07 moles of n2 to figure out how much our change in enthalpy of the system is going to be.
00:59
And then we can solve for change in entropy.
01:01
So first we have to solve for the change in enthalpy.
01:05
So the change in enthalpy is just for the reaction is the sum of the products minus the sum of the reactants.
01:21
So we just have one product.
01:22
We take the coefficient of two times its standard enthalpy of formation, which is 33 .85, and then minus the sum of the reactants, which they each have a coefficient of one, one times zero is zero.
01:41
So we're just saying zero plus zero.
01:45
So our change in enthalpy of the reaction is going to be two times 33 .85 minus zero, which is 67 .7.
01:57
And then remember our units are kilojoules per mole.
02:03
So this is saying that 67 .7 kilojoules of heat are produced for every one mole of the reaction.
02:11
But we have to figure out how much is being real is how much the change in enthalpy is for 2 .07 moles of nitrogen.
02:22
So we start out with 2 .07 moles of nitrogen...