00:01
So for this question we're trying to find the change in entropy for the surroundings.
00:06
So the equation that we're going to use is that the change in entropy for the surroundings is equal to negative the change in enthalpy of the system divided by the temperature.
00:26
So first we'll, we already know the temperature because we're at standard conditions.
00:31
So the temperature is going to be 298 kelvin.
00:35
But now we need to calculate the change in enthalpy of the system.
00:40
So i have the standard enthalpy of formation for all of the compounds in the reaction.
00:47
So we're going to solve the equation where the change in enthalpy of the reaction is equal to the sum of the standard enthalpy of formation of the products minus the sum of the standard enthalpy of formation of the reactants.
01:10
And then remember this n and m just represent the coefficients which are present in the reaction.
01:18
So change in enthalpy of the reaction is going to be equal to the sum of the products.
01:24
So when we have iron which is zero, it's going to be zero plus the aluminum oxide.
01:32
We just have one so it's going to be one times a negative 1669 .8 minus the sum of the reactants.
01:45
Aluminum is just zero so two times zero is zero plus the iron oxide has a coefficient of one so one times negative 822 .2.
01:57
And then just plug that into your equation, or plug that into your calculator and you should get negative 847 .6 kilojoules per mole.
02:17
So now we have the temperature which we can plug in here and we have the change in enthalpy of the reaction which is just the change in enthalpy for the system which we can then plug into there and solve for the change in entropy of the surroundings.
02:38
So they want the change in entropy to be in joules so first before we plug in the enthalpy let's change our kilojoules into joules...