In lab, you add 2.141 g salicylic acid to a 125 mL Erlenmeyer flask, as listed in the procedure. You carefully add 4.0 mL acetic anhydride and have your TA add 5 drops of sulfuric acid.
After completing the synthesis and filtering, you place the crystals to dry on an evaporating dish that weights 21.06 g. After drying, the crystals and evaporating dish weigh 23.232.
1. Calculate the percent yield of aspirin.

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant. 

The product formed when bao and h2o  react together is                        ba(oh)2that is  bao + h2o = ba(oh)21 mole of    bao    react  1 mole of h2o  to    form  1 mole  of ba(oh)2

The answer to your q the total mass is 73