energy than the reactants Enthalpy changes are normally quoted at standard conditions. Standard conditions are : • 1 atm pressure • 298 K (room temperature or 25oC) • Solutions at 1mol dm-3 • all substances should have their normal state at 298K Standard enthalpy change of formation In an exothermic reaction the ∆H is negative In an endothermic reaction the ∆H is positive When an enthalpy change is measured at standard conditions the symbol is used Eg ∆H The enthalpy of formation of an element
Free Enthalpy Thermodynamics Energy
energy released during bond forming = 2(799) + 4(460) + 2(41) = 3520 kJ enthalpy change of reaction = +2632 + (-3520) = –888 kJ mol-1 Born-Haber Cycle &
Premium Temperature Oxygen Hydrogen
by Bomb Calorimetry Cameron Fowler CHEM 457: Lab Section 4 Submitted: 11/4/10 Lab Group #3: Michael Hyle Neil Baranik Tim Riley Abstract: The enthalpy of combustion of naphthalene was experimentally determined to be -5030.44 ± 78.98 kJ/mol which was a 2.5% error from the literature value of -5160 ± 20 kJ/mol.2 The theoretical enthalpy of combustion of solid naphthalene was calculated to be -6862.68 kJ/mol using bond energies for the gaseous molecules‚ the heat of vaporization of liquid
Premium Thermodynamics Enthalpy
NAME_________________________________ STAMP________________ PERIOD____ PICTURES & GRAPHS A. The Atom 1. Calculate the average atomic mass using the spectrum below. 2. Answer the questions regarding the energy level diagram shown. a) The emission lines for the series above are in the IR‚ Vis and UV regions. Match the series with the region and justify your choice (FYI – AP you do not need to memorize the names of the series. IB will need to know then for next year). b) Would the wavelength
Premium Acid dissociation constant Chemical reaction Chemical kinetics
Thermodynamics of Borax C3C Justin Nevins Chemistry 200‚ Section M1A Introduction The purpose of the lab was to determine how the solubility of Borax (Na2B4(OH)4) and other thermodynamic quantities such as enthalpy‚ entropy‚ and Gibbs free energy depend on temperature. When Sodium borate octahydrate (Borax) dissociates in water it forms two sodium ions‚ one borate ion and eight water molecules. The chemical reaction is shown as: (reaction 1) A simple acid-base titration
Premium Entropy Thermodynamics Chemistry
AS Chemistry Revision-Chemistry for Life 1. Avagadro constant‚ 6.02 x 10²³ number of particles in 1 mole of a substance 2. Empirical formula-simplest ratio of atoms of each element in a compound 3. 4. Model of an atom Particle Mass on relative atomic scale Charge Proton 1 1+ Neutron 1 0 Electron Very small (0.00055) 1- 5. Radioactive isotopes Radiation What is it? Relative charge How does the nucleus change? Stopped by? Deflection in electric field? Alpha α Helium nuclei ⁴₂He +2 2 fewer
Premium Atom Energy
Energetics Worksheet 1. Calculate a value for the Lattice Energy of Calcium Chloride from the following data. Draw energy cycles Std. Enthalpy of Formation of CaCl2 = - 795 kJ/ mol Std. enthalpy of atomisation of calcium = + 177 kJ/mol Std. enthalpy of atomisation of Chlorine = +121 kJ/mol 1st ionisation energy of calcium = +590 kJ/mol 2nd ionisation energy of calcium = +1100 kJ/mol Electron Affinity of chlorine = -364 kJ/mol 2. Draw Born-Haber cycles and calculate the L.E. of Cu2O and CuO
Premium Energy Enthalpy Carbon dioxide
answers 1. Define ΔHfθ and ΔHcθ ΔHfθ the enthalpy change when 1 mole of a compound is formed from its constituent elements in their standard states measured under standard conditions ΔHcθ the enthalpy change when 1 mole of a compound undergoes complete combustion measured under standard conditions 2. Write an equation for the enthalpy of formation of butane C4H10 4C(s) + 5H2(g) C4H10(g) 3. Write an equation for the enthalpy of combustion of butane C4H10 C4H10(g) +
Premium Carbon dioxide Oxygen Ethanol
compound to be used in hand warmer. Calorimetry experiment was conducted by dissolving three ionic compounds‚ CaCl2‚ Na2CO3‚ and NaCl‚ in distilled water to measure the enthalpy of solution.
Premium Chemistry Chemical reaction Temperature
in hand with General Chemistry lecture course‚ which covers the following topics: 1. CHEMISTS AND CHEMISTRY. 2. ATOMS‚ MOLECULES AND IONS. 3. STOICHIOMETRY. 4. TYPES OF CHEMICAL REACTIONS AND SOLUTION STOICHIOMETRY. 5. GASES. 6. ENERGY‚ ENTHALPY‚ AND THERMOCHEMISTRY. 7. QUANTUM MECHANICS AND ATOMIC THEORY. 8. BONDING: GENERAL CONCEPTS.
Premium Chemistry