Consider the reaction: NO 2 (g) → NO(g) + 1/2 O 2 (g) The tabulated data were collected for the concentration of NO 2 as a function of time: a. What is the average rate of the reaction between 10 and 20 s? Between 50 and 60 s?

Hey everyone in this example, we need to calculate the rate of formation of oxygen gas between 10.20 seconds. Based on the gathered data for the given reaction. So based on this given reaction below, we want to write out a rate expression So that we can say our rate is equal to the change in concentration of our reactant. CO2 divided by the change in time. And we're going to set this equal to the change in concentration of our product Divided by the change in time. Now we need specific coefficients here and according to our given reaction, we have a coefficient of one in front of our CO2. So we would just have a negative one in front of our rate expression here in terms of its concentration because CO2 is a reactant and then as far as our oxygen, we have a coefficient of one half which we want in the denominator. So we would go ahead and make this positive or we would actually make this no longer a fraction. So it would just be positive too since we have this oxygen gas as a product. So plugging in what we know from our given equation here or the given data, we would go ahead and say that our rate is equal to The change in concentration for 02. We should have in our numerator, we can pick at any time and so let's do between Or from 20 seconds to 10 seconds. So we can have the concentration at 20 seconds because we want final, minus initial. Which is given in the chart as .819 Molar minus the concentration for C. 02 at 10 seconds which is given as 100.932 moller according to the chart. So this would be our numerator and then in our denominator we're gonna have our change in time. So because we picked 20 seconds we're going to have final time 20 seconds minus initial time 10 seconds. And so what we're going to do is set this equal to The right hand side which is two times are changing concentration of co two divided by our change in time. And so simplifying the left hand side we would say and sorry this should still have that negative one there. So in our next line we would have that our rate is equal to Positive 0.0113. And this is in units of polarity times inverse seconds. And this is still set equal to two Times are changin concentration of 02 divided by the change in time. And so now we want to go ahead and isolate for our change in concentration of 02. So we would have Both sides divided by two So that it can be canceled out here on the right hand side. And what we would get is that our change sorry our change in concentration of 02 divided by the change in time is equal to A value of 5.7 times 10 to the negative third power, and we still have units of polarity times inverse seconds. And so this would be our final answer for our rate of formation of according to the prompt. So I hope that everything I explained was clear. If you have any questions, please leave them down below, and I will see everyone in the next practice video.

Ch.15 - Chemical Kinetics

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Ch.15 - Chemical Kinetics

Problem 32a

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Chapter 15, Problem 32a

Consider the reaction: NO₂(g) → NO(g) + 1/2 O₂(g) The tabulated data were collected for the concentration of NO₂ as a function of time: a. What is the average rate of the reaction between 10 and 20 s? Between 50 and 60 s?

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Identify the change in concentration of NO2 between the times 10 s and 20 s, and between 50 s and 60 s. This can be done by subtracting the concentration of NO2 at the start time from the concentration at the end time for each interval.

Calculate the time intervals for each period. For the first interval, subtract the start time (10 s) from the end time (20 s). Do the same for the second interval, subtracting 50 s from 60 s.

Use the formula for average rate of reaction, which is the change in concentration divided by the change in time. Apply this formula separately for each time interval.

For the reaction NO2(g) → NO(g) + 1/2 O2(g), note that the disappearance of NO2 indicates the progress of the reaction. Therefore, the average rate should be expressed as a negative value, indicating the consumption of NO2.

Compare the average rates calculated for the two intervals to observe how the rate changes over time. This can provide insights into the kinetics of the reaction.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Reaction Rate

The reaction rate is a measure of how quickly reactants are converted into products in a chemical reaction. It is typically expressed as the change in concentration of a reactant or product per unit time. Understanding how to calculate the average rate involves determining the difference in concentration over a specified time interval.

Concentration

Concentration refers to the amount of a substance (solute) present in a given volume of solution or mixture. In the context of chemical reactions, it is crucial to know the concentrations of reactants and products at different times to calculate reaction rates. Concentration can be expressed in various units, such as molarity (moles per liter).

Time Intervals

Time intervals are specific periods during which measurements are taken to observe changes in a reaction. In this question, the average rate of reaction is calculated over two distinct time intervals (10-20 s and 50-60 s). Understanding how to analyze data over these intervals is essential for determining the average rate of the reaction accurately.