00:01
For this question, we're given three chemical reactions with known delta h values, and we're asked to determine the delta h value for 2 c solid plus h2 gas going to c2 h2 gas.
00:24
So to get this reaction, we need two carbon solids on the left -hand side, so we'll need to multiply this reaction by two.
00:35
When we multiply it by two, we multiply the delta h value by two.
00:43
Then we need one hydrogen on the left -hand side, one h2, we have that, and we need one c2 h2 on the right -hand side, so we're going to have to reverse this reaction.
00:57
When we reverse, oops, when we reverse a reaction, we change the sign from negative to positive.
01:10
So now we'll see that the two carbon dioxides are going to cancel, because these are now on the left -hand side, they'll cancel these on the right -hand side...