Many biochemical reactions are reversible Reversible reactions Learning Objectives: To investigate reversible reactions. Key words: reversible, condition, direction Mg + 2HCl  MgCl2 + H2 Wood reacting with oxygen Many biochemical reactions are reversible Irreversible Reversible

Reversible reactions and dynamic equilibrium Learning Objectives: To be able to write an equation to show a reversible reaction. To know that reversible reactions can reach a state of equilibrium. To know what dynamic equilibrium means. Key words: dynamic equilibrium Mg + 2HCl  MgCl2 + H2 Wood reacting with oxygen Many biochemical reactions are reversible Reversible Irreversible

Simple reversible reactions Heating copper sulphate The change from blue hydrated copper sulphate to white anhydrous copper sulphate is one of the most commonly known reversible reactions. Heat anhydrous copper sulphate CuSO4.5H20  CuSO4 + 5H2O hydrated copper sulphate steam

Heat Simple reversible reactions NH4Cl(s) NH3(g) + HCl(g) Heating ammonium chloride Ammonium salts are made by reacting ammonia with an acid but some of these salts will decompose back into reactants when heated. ammonium chloride ammonia hydrogen chloride NH4Cl(s) NH3(g) + HCl(g) Heat Heat makes the solid disappear as it changes into gases. Solid reappears as it changes back again in the cool part of the tube.

A B A B Dynamic equilibrium A reversible reaction is where products can, under appropriate conditions, turn back into reactants. Range of conditions over which both the forward and backward reaction will take place. This can lead to a state of balance with both reactants and products present in unchanging amounts. This is called a dynamic equilibrium. A B A B these combine these decompose

Equilibrium – unchanging amounts of reactants and products Dynamic equilibrium Equilibrium – unchanging amounts of reactants and products Dynamic – the reaction is still occurring Ac7.10 – Watch the demonstration and annotate the diagrams to describe dynamic equilibrium

Dynamic equilibrium How can equilibrium be used to explain the difference between strong and weak acids? P210-211

Chromatography as an application of dynamic equilibrium Whilst your chromatogram is running: Read p210-211 and make notes on the difference between strong and weak acids in terms of dynamic equilibrium. Read p222 and explain why chromatography is an application of dynamic equilibrium. Define the term Rf in relation to chromatography.