Chemistry Chapter 6 Reading Notes
Chemistry Chapter 6 Reading Notes CHEM-111
Popular in General Chemistry
verified elite notetaker
Popular in Chemistry
This 4 page Class Notes was uploaded by Madelyne Crawford on Tuesday October 11, 2016. The Class Notes belongs to CHEM-111 at Campbell University taught by Dr. Kesling in Fall 2016. Since its upload, it has received 3 views. For similar materials see General Chemistry in Chemistry at Campbell University.
Reviews for Chemistry Chapter 6 Reading Notes
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/11/16
Chapter 6: Thermochemistry By Madelyne Crawford 6.1: Chemical Hand Warmers Thermochemistry- study of the relationships between chemistry and energy Chemical reactions exchange energy with their surroundings 6.2: The Nature of Energy- Key Definitions REVIEW: o Energy is the capacity to do work o Work is the result of a force through a distance Heat- the flow of energy caused by a temperature difference (transfers energy) Kinetic energy- energy associated with the motion of an object o Kinetic energy= 0.5(mv^2) Thermal energy- energy associated with the temperature of an object o This is a type of kinetic energy because it arises from the motion of atoms or molecules within the substance Potential energy- energy associated with the position or composition of an object Chemical energy- energy associated with the relative positions of electrons and nuclei in atoms and molecules (also a form of potential energy) Law of conservation of energy- energy can neither be created nor destroyed o Energy is transferred from object to object and can take on different forms System- understanding and tracking energy changes through investigation o System’s surroundings- everything with which the system can exchange energy Joule (J)- SI unit of energy o 1 J= 1kg(m^2/s^2) calorie- 4.184 J Calorie- (nutritional unit) = 1000 calories o 1 Cal=1 kcal=1000 cal kilowatt-hour (KWh)- 3.60 X 10^6 J 6.3: The First Law of Thermodynamics- There is No Free Lunch thermodynamics- general study of energy and its interconversions o most fundamental laws of science 1. Law of energy conservation- the total energy of the universe is constant o with energy, you cannot get something for nothing- you can only break even o energy is ALWAYS conserved internal energy (E)- the sum of kinetic and potential energies of all of the particles that compose the system o this is a state function- value depends only on the state of the system, not on how the system arrived at that state o temperature, pressure, concentration, and physical state if reactants have high internal energy than products, the change in energy systems is negative and energy flows out of the system into the surroundings if reactants have low internal energy than products, change in energy systems is positive and energy flows into the system from the surroundings change in internal energy of the system= q + w (q is heat transferred and w is work done) 6.4: Quantifying Heat and Work thermal equilibrium- heat transfer from object to object stops because the two have reached the same temp; no additional transfer of heat heat capacity (C)- quantity of heat required to change its temp by one degree Celsius specific heat capacity- measure of the intrinsic capacity of a substance to absorb heat; amount of heat required to raise the temp of 1 gram of substance by one degree Celsius molar heat capacity- amount of heat required to raise the temp of one mole of substance by one degree Celsius pressure-volume work- occurs when force is caused by a volume change against an external pressure o w = -external pressure X change in volume 6.5: Measuring Change in Internal Energy for Chemical Reactions calorimetry- measures the heat evolved in a chem reaction; measure thermal energy exchanged between the reaction and the surroundings by observing change in temp bomb calorimeter- measures change in internal energy for combustion reactions o bomb= sealed container that ensures reaction occurs at constant volume 6.6: Enthalpy- The Heat Evolved in a Chemical Reaction at Constant Pressure enthalpy- sum of its internal energy and the product of its pressure and volume endothermic reaction- a chemical reaction with a positive change in enthalpy; absorbs heat from its surroundings exothermic reaction- chem reaction with a negative change in enthalpy; gives off heat to its surroundings enthalpy of reaction (or heat of reaction)- enthalpy change in a chem reaction; depends on the amount of material undergoing the reaction o amount of heat generated or absorbed depends on the amount of reactants that actually react 6.7: Constant-Pressure Calorimetry coffee-cup calorimeter- measures enthalpy change for chemical reactions (H rx) for many aqueous reactions o occurs at constant pressure and measures change in enthalpy for a reaction 6.8: Relationships Involving Enthalpy Change for Chem Reactions (H rx) 1. If a chemical reaction is multiplied by some factor, then the enthalpy change is also multiplied by the same factor 2. If a chemical equation is reversed, then the enthalpy changes sign 3. If a chemical equation can be expressed as the sum of a series of steps, then enthalpy change for the overall equation is the sum of the heats of reaction for each step o Hess’s law 6.9: Determining Enthalpies of Reaction from Standard Enthalpies of Formation Standard state: o For gas- pure gas at pressure of exactly one atm o For liquid or solid- pure substance in its most stable form at a pressure of one atm and the temp of interest (25 degrees C) o For substance in solution- concentration of exactly one M Standard Enthalpy change- the change in enthalpy for a process when all reactants and products are in their standard states Standard enthalpy of formation: o For a pure compound- change in enthalpy when one mol of the compound forms from its constituent elements in their standard states o For pure element- standard enthalpy of formation = 0 o Standard heat of formation 6.10: Energy Use and the Environment Different kinds of air pollutants: 1. Sulfur oxides- produced during coal-fired electricity generation and industrial metal refining 2. Carbon monoxide- forms during the incomplete combustion of fossil fuels and emitted by cars and trucks 3. Nitrogen oxides- emitted by motor vehicles, fossil-fuel based electricity generation plants, and high-temp combustion processes occurring in air o orange dark gas that causes dark haze over polluted cities 4. Ozone- produced when some products of fossil fuel combustion react in the presence of sunlight o photochemical smog- products of the reaction
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'