Question

• The rate of reaction is defined as

  Rate = −1∆[A] = −1∆[B] = + 1∆[C] = +1∆[D] ?? ∆?? ?? ∆?? ?? ∆?? ?? ∆??

• Average rate: the change in measured concentrations in any particular time period

• Instantaneous rate: the change in concentration at any one particular time

• Generally, the greater the concentration of reactant molecules, the faster the reaction

• Increasing temperature increases the reaction rate for most reactions

  Questions 1: Table I displays some data relating to an experiment 2NO (g) + O2(g) ? 2NO2(g)

  Table 1: Experimental data

  1. 1.1 Why is there a negative sign in equation (1)? Give a corresponding equation for the rate of production of a product.

  2. 1.2 Based on the data provided in Table 1, what is the average rate of consumption (M/s) for the NO(g) and O2(g) over the first 100 seconds? What is the rate of production (M/s) for the product, NO2(g)? (report three rates respectively)

  3. 1.3 Are the three rates you obtained in #2 the same? What is the potential problem you see if you use rate of consumption/production to characterize how fast the reaction proceed?

  4. 1.4 How shall we define rate of reaction that will give us unique value, independent of which

  species we are monitoring? Determine the rate of reaction accordingly for this problem.

Time (s)	[NO] (M)	[O2] (M)	[NO2] (M)
0	2.40	2.0	0
100	1.80	1.70	0.60

Answer 1