Unit 3 topic 1 :Chemistry Chemical equilibrium systems

• Strong acids: HCl, HNO3, H2SO4
• Weak acids: CH3COOH, H2CO3
• Strong base: KOH, Ba(OH)
• Weak base: NH3, CH3CH2NH2
• Acids increase the concentration of

  H+
• Bases increase the concentration of


  OH-
• limitation of Arrhenius model of acids and bases

  only describes acid-base reactions in water
• The bronsted lowry model

  > acids can donate protons and bases accept protons
• all acids contain

  hydrogen
• proton donor

  a substance that can donate H+
• monoprotic acid


  an acid that can donate one hydrogen ion per molecule
• polyprotic acid


  an acid that can donate more than one hydrogen ion per molecule
• strong acids ...

  completely dissociate in water
• strong bases ...

  bases that completely dissociates in water
• weak acids and weak bases ...

  only partially dissociate in water
• dilute vs concentrates and weak vs strong


  example

  
• A conjugate acid forms when 


  a base accepts an H+
• A conjugate base forms when an

  acid donates a H+
• the conjugate pairs 


  acid + conjugate base and base + conjugate acid
• acid -> conjugate base


  lose H+
• base -> conjugate acid


  gain H+
• Amphiprotic species 


  molecules or ions that can either donate or accept a proton and can therefore be and acid of a base, e.g h2o
• general equilibrium equation

  
• PH scale


  this is the

  
• acids are substances that increase


  the concentration of hydronium (H) ions
• bases have high concentrations 


  of hydroxide (-OH) ions
• pH = -log10=[H+]


  pH calculations
• [H+] = 10-pH


  inverse pH concentration calcualtion
• Calculating pOH


  pOH = -log10[OH-]
• calculating [OH-]


  pH+pOH=14
• inverse [OH-] 


  [OH-]= 10-pOH
• electrolyte 


  a substance that conducts electricity when melted or dissolved in a solution
• self ionisation of water

  the reaction in which a water molecule loses a hydrogen ion to become a hydorxide ion (OH-) and the hydrogen ion immediately reacts with another water molecule to form a hydronium (H3O-)
• ionic product constant of water

  Kw = the equilibrium constant for the self-ionisation of water
• Kw


  [H3O+][OH-] or [H+][OH-]
• Ka


  =[H3O][A-]/[HA]
• Kb

  [BH+][OH-]/[B]
• indicator 


  a substance that changes colour in the presence of different hydronium ion concentrations
• indicators 


  are added to solutions that already have an acid or base in them
• indicators


  ...