A flask is charged with 0.100 mol of A and allowed to react to form B according to the hypothetical gas-phase reaction A1g2¡B1g2. The following data are collected: Time (s) 0 40 80 120 160 Moles of A 0.100 0.067 0.045 0.030 0.020 (c) Which of the following would be needed to calculate the rate in units of concentration per time: (i) the pressure of the gas at each time, (ii) the volume of the reaction flask, (iii) the temperature, or (iv) the molecular weight of A?

Video transcript

Hi everyone. This problem reads a 0.78 mol C sample was allowed to react in a flask to produce d according to the hypothetical gas phase reaction. See yields de select the attributes needed to determine the rate in terms of concentration per time for the reaction taking place. Okay, So here we need to select the attributes needed to determine the rate. All right. And we see here that our hypothetical gas phase reaction were given time from zero seconds to 40 seconds and the moles that contribute to each. Okay. And so we need to determine the rate. And so let's take a look at what units. We report rate in those units, our mole per leader, which is also concentration. So what this means is we need to know the number of moles and we also need to know the volume of the container. Okay, So these are the two things we need and we're given moles here. Alright. So what our answer then is when it comes to selecting the attributes needed, we already have the moles but we don't have the volume. So the correct answer here is going to be answer choice. C volume of the container must be known. So that we can report the rate and units of concentration per time which is moles per leader. Okay, so that is it for this problem? I hope this was helpful