Is is possible to get 100% on a percent yield?

Now, For Cup A I had :
Mass of cup water & stirrer: 67.51
mass of sodium bicarbonate: 1.00g
mass of citric acid: .76g
total mass of all: 69.27g
mass of cup, solution, stir after reaction: 68.75g
difference (CO2 mass) = 0.52

My Theoretical yield is 0.52g CO2

So am I doing this right?
0.52gCO2/0.52gCO2 x 100%= 100%

With good technique and good equipment, it is possible to get very close to 100%. Your theoretical yield is 0.52 and you obtained 0.52 for CO2 so that is 100% yield. If you had weighed to two more places it may (or may not) have been exactly 100%. If you use 44.01 for molar mass CO2 and 84.007 for molar mass NaHCO3, the theoretical yield for CO2 is 0.5239 g. To two significant figures your 100% is OK.

To determine the percent yield, you need to compare the actual yield with the theoretical yield and calculate the percentage. In your case, the theoretical yield is 0.52g of CO2, which you have correctly identified.

To calculate the percent yield, use the following formula:

Percent Yield = (Actual Yield / Theoretical Yield) x 100%

In your case, the actual yield is not explicitly given, but it can be calculated by finding the difference in mass before and after the reaction:

Actual Yield = Mass of cup, solution, stir after reaction - Mass of cup water & stirrer

Actual Yield = 68.75g - 67.51g = 1.24g

Now, you can plug the values into the formula:

Percent Yield = (1.24g / 0.52g) x 100% ≈ 238%

The result you obtained (100%) suggests that your actual yield is equal to the theoretical yield, which is usually rare in most chemical reactions. Therefore, it is likely that there was an error in your calculations or measurements.

It is important to double-check your calculations and make sure the measurements are accurate to obtain a more realistic percentage.