1. If a reaction is first order for each of two reactants, its overall reaction order is
a.0
b.1
c.2
d.3
2. A straight line is obtained when graphing the natural log of concentration and time for
a. zero order reactions
b. first order reactions
c. second order reactions
d. none of the above
1. The overall order is 1 + 1 = 2
2. A straight line is obtained for a first order reaction.
To determine the overall reaction order for a reaction with two reactants, you need to consider the individual orders of each reactant as well as the sum of their orders.
1. If a reaction is first order for each of the two reactants, it means that the rate of the reaction is directly proportional to the concentration of each reactant raised to the power of 1.
When you have two first-order reactants, you can simply add their individual orders to find the overall reaction order:
First order + First order = 1 + 1 = 2
Therefore, the answer to the first question is: c. 2
Now let's move on to the second question:
2. Graphing the natural log (ln) of concentration against time is a common method to determine the order of a reaction.
a. For zero order reactions, the concentration does not affect the rate of the reaction. Consequently, the natural log of the concentration remains constant over time. Therefore, when graphing the natural log of concentration against time for a zero order reaction, you would obtain a straight line with a constant slope.
b. For first order reactions, the concentration decreases exponentially over time. When graphing the natural log of concentration against time for a first-order reaction, it results in a straight line with a negative slope.
c. For second order reactions, the rate of the reaction is directly proportional to the square of the concentration. The graph of the natural log of concentration against time for a second-order reaction will not result in a straight line.
Based on this information, the answer to the second question is: b. First order reactions.