Question

here is a graph of the pressure of nitrogen dioxide (no₂) in a reaction vessel during a certain chemical reaction. use this graph to answer the questions in the table below.
is no₂ being created or destroyed by the chemical reaction? created destroyed neither created nor destroyed
if no₂ is being created or destroyed, what is the rate at which it is being created or destroyed 900 seconds after the reaction starts? round your answer to 2 significant digits. also be sure your answer has the correct unit symbol.
if no₂ is being created or destroyed, what is the average rate at which it is being created or destroyed during the first 900 seconds of the reaction? round your answer to 2 significant digits. also be sure your answer has the correct unit symbol.

Explanation:

Step1: Determine creation or destruction

Observe the pressure - time graph. The pressure of $NO_2$ decreases over time. So, $NO_2$ is being destroyed.

Step2: Find the instantaneous rate at $t = 900$ s

To find the instantaneous rate at $t=900$ s, we need to draw a tangent to the curve at $t = 900$ s. Let's assume we estimate the slope of the tangent. If we consider two points on the tangent close to $t = 900$ s. Let the change in pressure $\Delta P$ and change in time $\Delta t$. The rate of destruction of $NO_2$ is given by the negative of the slope of the $P - t$ graph. However, without exact numerical values from a more precise scale, if we estimate from the graph, we can use the general formula for the rate $r=-\frac{\Delta P}{\Delta t}$.

Step3: Calculate the average rate in the first 900 s

The initial pressure $P_0 = 18.459$ atm and let the pressure at $t = 900$ s be $P_{900}$. The average rate of destruction of $NO_2$ in the first 900 s is $r_{avg}=-\frac{P_{900}-P_0}{900 - 0}=\frac{P_0 - P_{900}}{900}$. From the graph, if we estimate $P_{900}\approx7$ atm. Then $r_{avg}=\frac{18.459 - 7}{900}=\frac{11.459}{900}\approx0.013$ atm/s.

Answer:

Is $NO_2$ being created or destroyed by the chemical reaction? Destroyed
If $NO_2$ is being created or destroyed, what is the rate at which it is being created or destroyed 900 seconds after the reaction starts? (Estimated value) $0.013$ atm/s
If $NO_2$ is being created or destroyed, what is the average rate at which it is being created or destroyed during the first 900 seconds of the reaction? $0.013$ atm/s