Intro to chemistry Therm o A. A balanced equation that includes the physical states and the quantity of ______ released or absorbed as heat is known as a _____________ equation. energy thermochemical

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + 891kJ Intro to chemistry Therm o CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + 891kJ 2SO3(g) + 198kJ → 2SO2(g) + O2(g)

Intro to chemistry Therm o 1. The _______ (heat) of reaction, ΔHrxn, is the amount of ______ released or absorbed as ____ during a chemical reaction. enthalpy energy heat

Intro to chemistry Therm o Enthalpy change a. ________, H, is a name given to the heat content of a system (your reaction) that occurs at constant pressure. Although we cannot measure the actual enthalpy of a substance, you can measure the _______ in enthalpy, ΔHrxn ,which is the heat absorbed or released in a reaction. change

Intro to chemistry Therm o b. This amount of heat energy absorbed or lost by a system (your reaction) is known as the -________ change, ΔHrxn. For the purposes of this course, the change in enthalpy, ΔHrxn, is the same as Q. enthalpy

Intro to chemistry Therm o 2. _____________ equations are often written by designating the ___ of ΔH rather than writing the energy as a reactant or product. Thermochemical sign

Intro to chemistry Therm o CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) + 891kJ 2SO3(g) + 198kJ → 2SO2(g) + O2(g) CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) ΔH= -891kJ 2SO3(g) → 2SO2(g) + O2(g) ΔH=+ 198kJ

Intro to chemistry Therm o a. _______ ΔH indicate an _________ reaction. Heat is ________ into the surroundings. Negative exothermic released

Intro to chemistry Therm o

Intro to chemistry Therm o b. _______ ΔH indicate an __________ reaction. Heat is ________ from the surroundings. Positive endothermic absorbed

Intro to chemistry Therm o