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question 20 (1 point)
a student makes a graph of initial rate vs. concentration in order to determine the
order of a reaction. if the reaction is first order, what would she see on the graph?
a straight, horizontal line at the initial rate
a straight line slowly going down to zero
a straight line beginning at the origin and gradually increasing
a curved line showing an increase in rate
a curved line showing an decrease in rate
question 21 (1 point)

Explanation:

For a first - order reaction, the rate law is \( rate = k[A] \). When we plot \( rate \) (initial rate) versus \( [A] \) (concentration), the equation of the line is \( y = kx \) (where \( y=\text{rate}\), \( k \) is the rate constant, and \( x = [A] \)). In the equation \( y = kx \), when \( x = 0\) (no reactant, i.e., \( [A]=0 \)), \( y = 0\) (no rate). As \( x\) (\([A]\)) increases, \( y\) (rate) increases proportionally. A straight line with a positive slope passing through the origin (\(x = 0,y = 0\)) is the graph of a first - order reaction.

Answer:

a straight line beginning at the origin and gradually increasing