36.1 Introduction to rate of reactions
36.1 Introduction to rate A. Reactions have different reactions Very fast reaction: H2 + O2 – H2O (Explosive) Fast reaction : Mg + 2HCl – MgCl2 + H2 (React immediately) Slow reaction: Rusting: 4Fe + 3O2 + 2nH2O – 2Fe2O3.H2O (Takes week) B. Why do we study rate of reaction? So we can alter the rate of reaction. Favorable reaction (e.g. produce industrial): Speed up , produce product faster Unfavorable reaction (e.g. decay of food) : Slow down C. Rate of reaction Rate of reaction = change in conc of chemical / time Unit: mol dm-3 s-1 ✘ M s-1 Other possible unit: g min-1 / dm3 s-1 D. Mole ratio same as Rate ratio If mole ratio of A: B= 3: 4, Rate of A : Rate of B = 3: 4 E. Presentation Reactant : Rate of consumption of B // Rate of reaction = + x mol dm-3 s-1 Product: Rate of formation of A // Rate of reaction = - x mol dm-3 s-1
36.1 Introduction to rate A. Reactions have different reactions Very fast reaction: H2 + O2 – H2O (Explosive) Fast reaction : Mg + 2HCl – MgCl2 + H2 (React immediately) Slow reaction: Rusting: 4Fe + 3O2 + 2nH2O – 2Fe2O3.H2O (Takes week) B. Why do we study rate of reaction? So we can alter the rate of reaction. Favorable reaction (e.g. produce industrial): Speed up , produce product faster Unfavorable reaction (e.g. decay of food) : Slow down C. Rate of reaction Rate of reaction = change in conc of chemical / time Unit: mol dm-3 s-1 ✘ M s-1 Other possible unit: g min-1 / dm3 s-1 D. Mole ratio same as Rate ratio If mole ratio of A: B= 3: 4, Rate of A : Rate of B = 3: 4 E. Presentation Reactant : Rate of consumption of B // Rate of reaction = + x mol dm-3 s-1 Product: Rate of formation of A // Rate of reaction = - x mol dm-3 s-1