# 4.10: Rate Laws - Differential

Discussion -

Amount left: 30,   15,   7.5,   3.75
Time: 8:00  8:45  10:15   13:15
t'increment:     45    90    180      (min)

Calculate the time when 10 percent of the $$\ce{HI}$$ has decomposed.
• The dust explosion is a
1. homogeneous reaction
2. heterogeneous reaction
3. catalytic reaction
4. chain reaction

Hint: b. heterogeneous reaction

Discussion -
Chain reactions may lead to explosion, but dust explosion is not a chain reaction. Chemists explained the causes of a grain elevator explosion.

• For the reaction:

$$\ce{2 NO + O2 \rightarrow 2 NO2}$$,

the following results were obtained:
  run      [NO]     [O2]     Rate
1       0.12     0.05     0.12
2       0.12     0.10     0.24
3       0.24     0.05     0.48

What is the order of the reaction with respect to $$\ce{[NO]}$$?

Hint: 2

Discussion -
What is the order with respect to $$\ce{[O2]}$$?