Now, with the internal energy of a system, we have the internal energy formula. We're going to say this formula is used when we have the heat and work of a system. We know that Delta E equals Q plus w Delta E is our internal energy. It could be in either jewels or kill a jewels. Q represents our heat. It could also be in jewels or kill jewels and then w equals work. Now, with work, we have an additional formula here. The work formula is used when we have the pressure and volume of a system here, work equals negative p times Delta V. So we're gonna say here P equals pressure in atmospheres. V equals volume in leaders. And then we're gonna say leaders times atmospheres is equivalent to one a 1.3 to 5 jewels. Now, this is important because if a work is given in leaders times, atmospheres, then we use this conversion factor here to change it into jewels. And we're going to say here, connected to this idea of heat and work is another term envelop, which uses the variable of Delta H. We're going to say it represents the amount of heat released or absorbed during chemical reaction. It should sound kind of familiar to you. We're going to say here that at constant pressure, entropy and heat can be treated as the same variable. So a constant pressure. We're going to say here that entropy, which is Delta H, is equal to heat, which is cute. So keep these formulas in mind because remember, if it has a purple box around it, that means you're responsible for memorizing it for any upcoming quizzes or exams. So remember, internal energy equals Q Plus W, and work equals negative pressure. Times change in volume.