Chem 1B Dr. White
1
Worksheet 23 – Reaction Rates & Rate Laws
1) What are the usual units of reaction rate?
2) Concentrations of trace gases in the atmosphere are sometimes expressed in
molecules/cm3. If these units are used for the concentrations, then what are the units for the
reaction rate?
3. The compound RX3 decomposes according to the equation
3RX3 → R + R2X3 + 3X2
In an experiment the following data were collected for the decomposition at 100°C. What is
the average rate of reaction over the entire experiment?
t(s) [RX3](mol L-1)
0 0.85
2 0.67
6 0.41
8 0.33
12 0.20
14 0.16
4. Consider the following reaction
8A(g) + 5B(g) → 8C(g) + 6D(g)
If [C] is increasing at the rate of 4.0 mol L-1s-1, at what rate is [B] changing?
5. For the reaction
3A(g) + 2B(g) → 2C(g) + 2D(g)
the following data was collected at constant temperature. Determine the correct rate law for
this reaction.
Trial Initial [A] Initial [B] Initial Rate
(mol/L) (mol/L) (mol/(L·min))
1 0.200 0.100 6.00 × 10-2
2 0.100 0.100 1.50 × 10-2
3 0.200 0.200 1.20 × 10-1
4 0.300 0.200 2.70 × 10-1
