Rate Laws Estimating Rate Rate Law n An

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Rate Laws & Estimating Rate

Rate Laws & Estimating Rate

Rate Law: n An expression relating the rate of reaction to the concentration of

Rate Law: n An expression relating the rate of reaction to the concentration of the reactants

For: a. A + b. B → c. C + d. D a [B]b

For: a. A + b. B → c. C + d. D a [B]b Rate = k [A] n Rate equation: Rate constant: • determined experimentally for each reaction at given temp • L/mol • s or s-1 • Large k = fast reaction • Small k = slow reaction Coefficients: • Coefficients become the exponents

REMEMBER: Rate in this equation is dependant on the concentration of reactants only.

REMEMBER: Rate in this equation is dependant on the concentration of reactants only.

NO 2(g) + O 3(g)→ NO 3(g) + O 2(g) What is the rate

NO 2(g) + O 3(g)→ NO 3(g) + O 2(g) What is the rate equation for the formation of NO 3(g) and O 2(g)? Rate = k [NO 2][O 3] If the initial conc of NO 2(g) and O 3(g) is 1. 0 M, what would happen to the rate if we increased the conc of NO 2 to 2. 0 M? Rate doubles! Rate = k [1][1] Rate = k [2][1] Rate = 1 k Rate = 2 k

2 NO + O 2 → 2 NO 2 What is the rate equation

2 NO + O 2 → 2 NO 2 What is the rate equation for the formation of NO 2? Rate = k [NO]2[O 2] If the initial conc of both reactant is 1. 0 M, what would happen to the rate if we increased the conc of O 2 to 2. 0 M? Rate = k [1]2[1] Rate = 1 k NO to 2. 0 M? Rate = k [2]2[1] Rate = k [1]2[2] Rate = 2 k Rate = 4 k Rate doubles! Rate quadruples!

Predicting Rates of Reactions: n Reactions that have reactants: ¨ With oppositely charged ions

Predicting Rates of Reactions: n Reactions that have reactants: ¨ With oppositely charged ions are very fast Ag+ + Cl- Ag. Cl ¨ With few or weak bonds are faster than those with many or strong bonds Mg + HCl Mg. Cl + H 2 C 2 H 5 OH + 3 O 2 2 CO 2 + 3 H 2 O

Predicting Rates of Reactions: ¨ In the same phases are faster that those in

Predicting Rates of Reactions: ¨ In the same phases are faster that those in different phases H 2 (g) Mg (s) + 2 H 2 O (l) + F 2 (g) 2 HF (g) 2 Mg 2+ (aq) + 2 OH- (aq) + H 2 (g) ¨ Undergoing a two particle collision are faster than those requiring many particle collisions 2 H 2 (g) + O 2 (g) 2 H 2 O (g) 4 NH 3 (g) + 7 O 2 (g) 4 NO 2 (g) + 6 H 2 O (g)

Rank the following from fastest to slowest. 1. H 2 (g) + F 2

Rank the following from fastest to slowest. 1. H 2 (g) + F 2 (g) 2. Ag+ + Cl- 3. C 2 H 5 OH + 3 O 2 2 1 2 HF (g) Ag. Cl 2 CO 2 + 3 3 H 2 O

Which would have the greatest rate? A. Hg (l) + Br 2 (g) B.

Which would have the greatest rate? A. Hg (l) + Br 2 (g) B. 2 H 2 (g) + O 2 (g) Hg. Br 2 (s) 2 H 2 O (g) C. Ag+ (aq) + Cl- (aq) Ag. Cl (s) D. 4 NH 3 (g) + 7 O 2 (g) 4 NO 2 (g) + 6 H 2 O (g) C