Chemistry Book Notes: Chapter 21: Buffers and the Titration of Acids and Bases 21-1 Henderson-Hasselbalch Equation THE HH EQUATION OFTEN CAN BE USED TO CALCULATE THE pH OF A BUFFER SOLUTION -buffer >a solution containing both a weak acid and its conjugate base can resist a change in pH by neutralizing either an added acid or an added base. Ex. acetic acid-acetate soln (acid with conj. Base) > Kc for a buffer reaction can = 1/Ka or 1/Kb if you add an acid or base because
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WJEC CBAC AS/A LEVEL GCE in Chemistry REVISION AID UNIT 1 AS UNIT CH1 – Controlling and Using Chemical Changes (in order to make things‚ produce energy and solve environmental problems) Preamble This unit begins with some important fundamental ideas about atoms and the use of the mole concept in calculations. Three key principles governing chemical change are then studied‚ viz. the position of equilibrium between reactants and products‚ the energy changes associated with a
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exothermic B. is endothermic C. has H > 0 D. both a and c are correct E. both b and c are correct 4. Calculate the heat of vaporization of carbon tetrachloride given that the standard molar enthalpy of formation of liquid carbon tetrachloride is -135.4 kJ/mol and the standard molar enthalpy of formation of gaseous carbon tetrachloride is -102.9 kJ/mol. A. +102.9 kJ/mol B. -32.5 kJ/mol C. +238.2 kJ/mol D. +32.5 kJ/mol E. -238.2 kJ/mol 5. The complete combustion of 1 mole of
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Hess’s Law Mengyuan Wu (Millie) 7 January‚ 14 Aim: The purpose of this experiment is to determine the enthalpy change for the reaction: Introduction: It is impossible to measure the enthalpy change for this reaction directly because the process cannot be controlled. However‚ you can calculate this enthalpy change by using the Hess’s Law. Pre- lab Calculations: Calculation 1: Required Masses for Reaction The ratio of and is required to be 1:100 for Table 1: Calculation
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Reactants in a Chemical Reaction 9/6/13 Introduction The purposes of this lab are to measure the temperature change of the reaction between solutions of sodium hydroxide and phosphoric acid‚ calculate the enthalpy‚ H‚ of neutralization of phosphoric acid‚ and compare the calculated enthalpy neutralization with the accepted value. Theory Calorimetry is the measurement of change of heat in a reaction. A calorimeter is a tool to measure the amount of heat exchange in a chemical reaction (Helmenstine
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heat‚ depending on the reacting substances. Calorimetry is the process of measuring the heat flow between a system and its environment. The device used to measure this heat transfer is called a Calorimeter. The measurement of this heat is called the enthalpy of the reaction (∆H). There are two types of calorimeter. The first is a bomb calorimeter where the reaction takes place at constant volume. The other type is the coffee cup calorimeter‚ wherein the pressure is held constant while the reaction
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SUPPLEMENTARY MATERIAL I Unit V: States of Matter 5.7 KINETIC ENERGY AND MOLECULAR SPEEDS Molecules of gases remain in continuous motion. While moving they collide with each other and with the walls of the container. This results in change of their speed and redistribution of energy. So the speed and energy of all the molecules of the gas at any instant are not the same. Thus‚ we can obtain only average value of speed of molecules. If there are n number of molecules in a sample and their individual
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DATE PERFORMED: NOVEMBER 14‚ 2012 CALORIMETRY INSTITUTE OF CHEMISTRY‚ COLLEGE OF SCIENCE UNIVERSITY OF THE PHILIPPINES‚ DILIMAN QUEZON CITY‚ PHILIPPINES RECEIVED NOVEMBER 20‚ 2012 INTRODUCTION Heat is a form of energy that can be passed from an object with high temperature to an object with low temperature. The heat required to change the temperature of a substance by 1 K is called heat capacity. A calorimeter is a device commonly used to measure the amount of heat that
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Chemical Energetics All about enthalpy‚ calorimetry and the First Law of Thermodynamics A Chem1 Reference Text Stephen K. Lower • Simon Fraser University1 Contents Part 1: Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 Part 2: Basic thermodynamics: what you need to know . . . . . . . . . . . . . . . . . . 5 Systems and surroundings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Properties
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Design Objective: Find the standard molar enthalpy of combustion for magnesium. Manipulated Variables- volume of HCl‚ length of magnesium strip‚ mass of magnesium oxide‚ Controlled Variable- type of calorimeter (Styrofoam cup) Responding Variable- change in temperature Procedure: 1. Cut out 3 pieces of magnesium strips each with lengths of maximum 5 centimeters. 2. Measure and record the lengths of the magnesium. 3. Scrub the magnesium strips with steel wool to clean out impurities
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