00:01
So today, we're told that a student dissolves 13 .8 grams of lithium chloride and 300 grams of water.
00:07
We're also told that the temperature rises from 20 degrees celsius to 34 .8 degrees celsius.
00:14
And so today, we're going to calculate some values about this.
00:18
Our first thing is that we're going to calculate the heat of the reaction.
00:22
And we're going to use the formula, q equals m, c, delta, t, or q equals mcat.
00:28
So q is our enthalpy, or heat, m is our mass.
00:33
So our mass is going to be the water, 300 plus lithium chloride 13 .8, times c, the specific heat, which is 4 .184 joules per gram per celsius, and times the change in temperature, so 34 .8 minus.
01:00
20 degrees celsius, and this gives us that our heat or our enthalpy is equal to, oh, there should be a negative here, so negative 13 ,239 .18, or if we round to three sighings, negative, negative 13 ,200.
01:22
Okay? and so this means that because our enthalpy is negative, this is an exothermic reaction.
01:34
And we can really already see this because our temperature rose...