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Question
For a chemical reaction R → P, the variation in the concentration (R) vs. time (t) plot is given as:
(i) Predict the order of the reaction.
(ii) What is the slope of the curve?
(iii) Write the unit of rate constant for this reaction.
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Solution 1
For a chemical reaction R→P, the variation in the concentration (R) vs. time (t) plot is given as follows:
(i) The order of the reaction zero.
(ii) Slope = -k
Solution 2
(i) Predict the order of the reaction
The graph shows a straight line when concentration of reactant R is plotted against time t.
[R] = [R]0 − kt
Since the plot is a straight line with a negative slope, the reaction is zero order.
(ii) Slope of the curve
From the zero-order equation:
[R] = [R]0 − kt
The slope of the [R] vs t graph is −k (negative of the rate constant).
(iii) Unit of rate constant
For a zero-order reaction:
Rate = k
Rate has units of concentration/time.
If concentration is in mol L−1 and time in seconds:
Unit of k = mol L−1s−1
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\[\ce{A(g) + 2B(g) -> 2C(g)}\]
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Initial concentration of [B]/mol L–¹ |
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(i) What is the order of the reaction?
(ii) What is the slope of the curve?
(iii) What are the units of rate constant?
Match the graph given in Column I with the order of reaction given in Column II. More than one item in Column I may link to the same item of Column II.
| Column I | Column II | |
| (i) |  |
|
| (ii) |  |
(a) 1st order |
| (iii) |  |
(b) Zero-order |
| (iv) |  |
Identify the order of reaction from the following unit for its rate constant:
L mol–1 s–1
Higher yield of NO in \[\ce{N2(g) + O2 <=> 2NO(g)}\] can be obtained at:
[ΔH of the reaction = +180.7 kJ mol−1]
- higher temperature
- lower temperature
- higher concentration of N2
- higher concentration of O2
Choose the correct answer from the options given below:
