chp21. thermo chemistry

• alkanes


  liked by single bonds end in -ane
• cyclohexane 


  diamond shape
• alkenes


  double bonds end in -ene
• alkynes


  only one ethyne end in -yne
• organic chemistry


  study of compounds of carbon
• fossil fuels

  fuels that were formed from the remains of plants and animals that lived millions of years ago
• saturated compounds

  only single bonds between atoms in a molecule
• homologous series


  series of compounds of similar chemical properties, showing gradations in physical properties, general formula, similar method of preparation, differing from each other by a ch2 unit
• structural isomers


  same molecular formula but different structural formulas
• unsaturated compounds


  contains one or more double or triple bonds between atoms in the molecules
• aliphatic compound


  organic compound that consists of open chains of carbon atoms and closed chain compounds(rings) that resemble them in chemical properties
• aromatic compounds


  compounds that contain benzene ring structure in their molecules
• auto- ignition


  premature ignition (explosion) of the petrol-air mixture before normal ignition of the mixture by a spark takes place
• octane number


  measure of the tendency of the fuel to resist knocking
• catalytic cracking


  breaking down of long chain hydrocarbon molecules by the action of hat and catalysts into short chain molecules for which there is greater demand
• heat of reactions

  heat change when the number of moles of reactant indicate in the balanced equation for the reaction read completely
• heat of combustion

  heat change when one mole of the substance is completely burned in excess oxygen
• kilogram calorific value


  heat energy produced when 1 kg of the fuel is completely burned in oxygen
• bond energy

  average energy required to break one mole of a particular covalent bond and to separate the neutral atoms completely from each other
• heat of neutralisation


  heat change when one mole of h+ ions from an acid reacts with one mole of OH- ions from a base
• heat of formation

  of a compound is the heat change that takes place when one mole of a compound in its standard state is formed from its elements in their standard states
• hess's law


  if a chemical reaction takes place in a number of stages the sum of the heat changes in the separate stages is equal to the heat change if the reaction is carried out in one stage
• law of conservation of energy

  energy cannot be created of destroyed but only converted from one form of energy into another
• hydrocarbon


  compound that contains carbon and hydrogen only
• exothermic reaction


  chemical reaction that produces heat
• endothermic reaction


  chemical reaction that takes in heat