Definitions: Flashcards
(15 cards)
Relative molecular mass (Mr):
Mass of molecule of a substance compared to 1/12th of carbon-12. No units.
One dalton is 1/12th of C-12
Molar mass:
Mass of one mole of a substance. G/mol.
Molecular mass:
mass of molecule expressed in atomic mass units (Amu) or daltons (da)
Entropy:
Degree of disorder in a system (J/molK)
Second law:
Entropy of universe must increase for a process to occur spontaneously.
First law:
Law of conservation energy. Energy can’t be created or destroyed but can be synthesised. Total energy of a system and surroundings is constant.
Energy:
Degree of order in a given system. Capacity to do work.
Thermodynamics:
Transformations in energy that occur during processes in which a system changes from one state to another.
System tends towards position of lowest energy so minimum amount of work is required.
Depends on entropy, enthalpy and Gibbs.
Shows direction of reaction but not rate or how it goes.
Tells maximum amount of energy available for a process.
Chemical equilibrium:
Forward and reverse reaction occur at equal rate.
Conc of products and reactants don’t change over time.
State of lowest energy and can do no work. Stable/balanced system.
Spectroscopy:
Use of ER to characterise matter.
Look at interactions between them. Can be used to identify and characterise molecules.
Resonance spectroscopy:
Match frequencies to see motion of particle.
Two types:
1. Constructive interference
2. Destructive interference
Constructive interference:
Two waves with same frequency and phase can produce greater intensity of waves.
Destructive interference:
Two waves with same frequencies are 180 degrees to each other so cancel each other out.
Joule:
Is the energy exerted by a force of one Newton acting to move an object through a distance of one metre.
Newton:
Is the amount of force required to accelerate a mass of one kilo gram at a rate of one metre per second.
