Enthalpy and Entropy

Description

OCR AS level Salter's course
poppyekoronka
Mind Map by poppyekoronka, updated more than 1 year ago
poppyekoronka
Created by poppyekoronka about 11 years ago
109
1
1 2 3 4 5 (0)

Resource summary

Enthalpy and Entropy
  1. An exothermic reaction gives out energy from the system to the surroundings.
    1. The temp of surroundings increases
      1. ^H is negative
      2. An endothermic reaction takes energy into the system from the surroundings.
        1. The temp of surroundings decreases
          1. ^H is positive
          2. The standard enthalpy of combustion is H(theta) C, is the enthalpy change when 1 mol of substance burns completely in oxygen under standard conditions
            1. The standard enthalpy change of formation ^H(theta)f, is the enthalpy change when 1 mol of a substance is formed from its constituent elements. Both the reactants and the products are in their standard state
              1. Any other reaction is can be given the symbol ^h(theta)r, if the are done under standard conditions
                1. Measuring enthalpy in the lab
                  1. Measure the temperature rise when a known volume of water is heated by the complete combustion of a measured mass of fuel
                    1. energy transferred= mass of water x heat capacity of water x temp. change
                      1. This works out the enthalpy change for 1 mole of fuel used
                    2. Entropy is a measure of the number of ways in which particles can be arranged- it is a measure of disorder
                      1. Gases> liquids > solids - in order of greatest entropy
                        1. Mixtures have a greater entropy than the unmixed constituents
                          1. If the number of particles INCREASES during a the course of a reaction then entropy usually increases
                        2. Energy Density
                          1. energy density = enthalpy change of combustion x amount of fuel
                          Show full summary Hide full summary

                          0 comments

                          There are no comments, be the first and leave one below:

                          Similar

                          Acids and Bases
                          silviaod119
                          Elements, Compounds and Mixtures
                          silviaod119
                          Chemistry General Quiz - 2
                          lauren_johncock
                          Chemistry Quiz General -3
                          lauren_johncock
                          AS Chemistry - Enthalpy Changes
                          Sarah H-V
                          The Periodic Table
                          asramanathan
                          Acids, Bases and Salts
                          asramanathan
                          Chemical Symbols
                          Keera
                          Chemistry GCSE Review - States of Matter, Particles, Atoms, Elements, Compounds and Mixtures
                          Morgan Overton
                          Acids and Bases
                          Sarah Egan