The experimental data you entered is:

Trial #1 Trial #2 Trial #3
Mass: gelatin capsule (g) .123 .118 .122
Mass: whole alka-seltzer tablet (g) 3.230 3.230 3.230
Mass: capsule + alka-seltzer sample (g) .822 .882 .677
Mass: system before reaction (g) 23.109 23.110 22.735
Mass system after reaction (g) 21.742 21.813 21.500
Temperature (°C) 21.9 22.1 22.4
Pressure (mmHg) 778 778 778
Volume of water collected (mL) 76.3 78.1 77.3

Answer the following questions using the data you collected in the lab:

Trial #1 Trial #2 Trial #3
Calculate the mass (g) of alka-seltzer in each capsule :

Trial #1 Trial #2 Trial #3
Calculate the mass (g) of NaHCO3 reacted in each sample :

Trial #1 Trial #2 Trial #3
Calculate the percent mass of NaHCO3 in each sample (%):

Calculate the average percent mass of NaHCO3 in the sample.

3 answers

Some of this I'm sure you know how to do? If you want to show the experiment perhaps we can help you through it but no one here will write your lab report for you.
Im not sure how to do these questions though
We don't know what you're doing. No directions. You didn't write the procedure you are using therefore I can help you. If you want to post the procedure I suggest you post a new question at the top of the page.