For Cup C

Question

Mass of cup,water,stirrer: 55.15
Mass of sodium bicarbonate: 2.02g
mass of citric acid: 0.77g
total mass: 57.94g
mass of cup,solution, stirrer after reaction: 57.64
difference (CO2): 0.30g

Calculate the theoretical yield of carbon dioxide in the plastic cup C.

** u said**If citric acid is the LR then you should use it to determine the theoretical yield. This calls into question some of the earlier answers since I didn't check them for the LR bit. But it stands to reason that if 1 g NaHCO3 is equivalent to 0.76 g citric acid then if you start with 2.02 g NaHCO3 it will take more than 0.76 g citric acid and there isn't enough there to do anything except with 1g NaHCO3.

So I should be saying 0.008/84 *44? = 0.42% or am I to use the citric acid mass of 192.1? 0.008/192.1 = 0.00042 * 44 ==0.0018 I'm even more confused now... And before I didn't have to calculate the limiting reagent it's just now asking me to.. I don't know.. ughhhhhh..

Answer 1

I don't know why the delay in discussing/asking questions about limiting reagents but then I'm not teaching the course.

To recap, I think you had 2.02g NaHCO3 and 0.77 g citric acid (or was that 0.76 g). To determine the LR reagent and the theoretical yield, I do these the long way.
question 1. How much CO2 can be produced if we used ALL of the NaHCO3 and had all of the citric acid needed.
(2.02/84) x (3 mol CO2/3 mol NaHCO3) x (44 g CO2/1 mol CO2) = about 1.06g CO2

question 2. How much CO2 can be produced if we used ALL of the citric acid and had all of the NaHCO3 needed?
(0.77/192.1) x (3 mol CO2/1 mol citric acid) x (44 g CO2/1 mol CO2) = about 0.53g.

In limiting reagent problems the SMALLER amount always wins because you can't produce more than the limiting reagent will allow. So you will produce about 0.53 g CO2, all of the citric acid is used, some of the NaHCO3 is used and there is some unused. I hope I don't have the numberrs mixed up. I'm trying to do this from memory. (Note: the reason I like to do these LR problems the long way is because when I finish I have the answer to two questions; i.e., 1 is which is the limiting reagent and 2 is how much CO2 was produced and I get that number for calculating theoretical yield. So it may be the long way for some people but I get the complete answer instead of having to work two separate problems of one for the LR part and one for the TY part.

I mention the getting numbers confused because I see your 0.008/192.1 = 0.00042 and I don't know where that came from. Perhaps I do have my numbers mixed up.