Chemistry Study Skills

1. Chemistry Study Skills Annie McDougall, Kimberly Ellis, Brandon Mui, AnjamIftikhar, RachealKomuhendo

2. First Half of Chapter 5 • The First Law of Thermodynamics states that energy is neither created nor destroyed, it is simply converted to different forms of energy through the reaction. Energy is either absorbed by the system or released by the system. • There are both endothermic and exothermic reactions, that respectively absorb heat and release heat. • Internal energy is the sum of all potential and kinectic energy. It can only be measured by state, from solid to liquid to gas, not on the pathway that leads to there. • Heat flow can be accounted for by measuring enthalpy; enthalpy is internal energy plus the product of pressure and volume. • ∆H is the measure of the enthalpy of a reaction, otherwise known as the heat flow.

3. Questions • Is there any other way to transfer energy rather than heat? • Is the internal energy of the system just the kinetic and potential energy of the components, no other energy is calculated?

4. Second Half of Chapter 5 • ∆H is the measure of the heat flow of a reaction. If the system absorbs heat, or the surrounds lose heat, then the reaction is described as endothermic. If the system releases heat, or the surroundings gain heat, then the reaction is described as exothermic. • A calorimeter can be used to indirectly measure the enthalpy of a reaction. A coffee-cup calorimeter or a bomb calorimeter can be used to do this in the lab. • Hess’s law states that, “If a reaction is carried out in a series of steps, the overall reaction will be equal to the sum of the enthalpy changes for the individual steps.” • ∆Hf is the enthalpy of formation and is defined as the enthalpy change for the reaction in which a compound is made from its elemental components in their elemental form.

5. Questions • Does the stability of an element, or a compound affect the delta H of a reaction? • When reactions occur, are they entirely endothermic or exothermic? Or can the reactions be a combination of exothermic and endothermic components like in Hess's Law?

6. Chapter 5 Consensus • The First Law of Thermodynamics states that energy is neither created nor destroyed, it is simply converted to different forms of energy through the reaction. Energy is either absorbed by the system or released by the system. • ∆H is the measure of the heat flow of a reaction. If the system absorbs heat, or the surrounds lose heat, then the reaction is described as endothermic. If the system releases heat, or the surroundings gain heat, then the reaction is described as exothermic. • Internal energy is the sum of all potential and kinetic energy. It can only be measured by state, from solid to liquid to gas, not on the pathway that leads to there. • Hess’s law states that, “If a reaction is carried out in a series of steps, the overall reaction will be equal to the sum of the enthalpy changes for the individual steps.” Questions:1. Is there any other way to transfer energy rather than heat?2. When reactions occur, are they entirely endothermic or exothermic? Or can the reactions be a combination of exothermic and endothermic components like in Hess's Law?3. Does the stability of an element, or a compound affect the delta H of a reaction?