Ch6 lec 3

(4/14/20, bes)

Greetings Gen Chem folks!

This week we are going to continue our discussions of thermochemistry (Ch 6). In previous lecture notes we have covered the critical content associated with Sections 6.1-6.5. There is a lot more in these section then i have discussed, so focus on these lecture notes and not so much on the extended textbook material. As noted, all chemistry and biochemistry majors will be required to take Chem 312: Thermodynamics in their junior and senior year where we will get into more of the details.

Review of Section 6.4: Enthalpy

- Nearly all chemical reactions generate (exothermic) or consume (endothermic) energy/heat.

- We tabulate the amount of heat involved in an rxn using the enthalpy (ΔH) which most often has units of J or kJ per mol, kJ/mol of something.

Remember, some of this can be confusing because the ΔH units can be displayed as just kJ or kJ/rxn <--as written. Depending on the stoichiometric coefficients, this is per X mole of reactant or product.

- The types of problems that are asked involve:

Q1: Given the ΔH for a reaction, determine how much heat is generated (implying exothermic reaction) when X moles of a reactant is converted to products.

Q:2 Given the ΔH for a reaction, determine how much heat is generated (implying exothermic reaction) when Y grams of a reactant is converted to products.