Question

Explain average and instantaneous rate of reaction and describe two factors which affect them.

Hint:

Instantaneous rate is always obtained from the tangent to the concentration vs. time curve, while average rate comes from a secant line over a time interval.

Answer 1

Step 1: Average Rate of Reaction.
The average rate of reaction is the change in concentration of reactants or products divided by the time interval during which the change occurs. \[ \text{Average rate} = \frac{-\Delta [R]}{\Delta t} = \frac{\Delta [P]}{\Delta t} \] Step 2: Instantaneous Rate of Reaction.
The instantaneous rate of reaction is the rate at a specific moment of time. It is obtained by finding the slope of the tangent to the concentration-time curve at that instant. \[ \text{Instantaneous rate} = -\frac{d[R]}{dt} = \frac{d[P]}{dt} \] Step 3: Factors Affecting Reaction Rates.
Two important factors are: 1.
Concentration of Reactants: Higher concentration increases the frequency of collisions, leading to a faster rate.
2.
Temperature: Increasing temperature raises the kinetic energy of molecules, resulting in more effective collisions and faster reaction rate.
Conclusion:
The average rate gives a broad measure over an interval, while instantaneous rate measures the exact speed of reaction at a given time. Both are influenced by factors like concentration and temperature.