General definitions Flashcards
Define biofuel.
- a fuel derived from organic or living matter
Define carbon-neutral.
An activity that has no net carbon emissions to the atmosphere
Define the terms addition and elimination.
Addition: a chemical reaction in which two molecules form a larger molecule, or one which increases the number of substituents on a molecule
Elimination: a reaction in which a simple molecule is removed from a larger molecule
Define electronegativity.
The power/tendency of an atom to attract the pair of electrons in a covalent bond
Define enthalpy of formation.
- The enthalpy change when 1 mole of a substance is formed from it’s constituent elements, with all reactants and products in their standard states at standard pressure
Explain, in general terms, how a catalyst works.
- a catalyst provides an alternative route which has a lower activation energy.
Define enthalpy of combustion.
-The enthalpy change when 1 mole of a substance is burned completely in excess oxygen, with all reactants and products in their standard states, under standard pressure
Define Hess’s Law.
-The enthalpy change of a reaction is independent of the route taken, and only depends on the initial and final states.
Define enthalpy
- Heat change at constant pressure.
Define activation energy.
- The minimum energy particles require for a reaction to occur.
Suggest all 5 reasons why the enthalpy of combustion from an experiment may not be that in a databook.
-not standard conditions
-evaporation of water/fuel
-heat loss to surroundings
-incomplete combustion
-heat transferred to container
In an experiment to obtain the enthalpy of combustion of a hydrocarbon, the value a student obtains is much less than the value in a databook. Give as many possible ways the experimental apparatus/method could be improved.
-Use a lid
-insulate the container
-use a wind shield
