5. A student determines the mass of a 100 mL beaker filled with 50 mL of water to be 154.34 grams. After a tablet reacts with the water, the mass including the dissolved tablet is 157.26 grams.

Question

If you could provide an explanation that would be awesome! Id really like to grasp this concept.

Answer 1

Hi again, Anna!

I'll be glad to help you here (if I can)! To be honest, this only looks like "half" of a question, but here goes. Imagine that YOU are that student. For some reason (let's just say that your teacher asked you to do this!), you pick up a 100 mL glass beaker, and fill it about halfway so that you now have a beaker with 50 mL of water in it. You then walk that over to a balance, and the weight of the ENTIRE SYSTEM (that's the beaker plus the water that you just put into it) is 154.34 grams. You then remove the beaker from the balance, and carefully walk this back to your bench. You then take a tablet (?) which was provided for this experiment, and drop this into that same beaker. It sounds like the tablet eventually dissolves (as tablets do, you know), and you then take this beaker back to the balance where you weigh it again. The new weight of the ENTIRE SYSTEM (beaker, water, and dissolved tablet) is 157.26 grams.

Uhhh, that's it! Was there more to this? Were you supposed to calculate the weight of the tablet? Or was there something in the fact that the table "react[ed] with the water"? Without knowing the rest of the question, you could quickly calculate that the amount of "tablet" remaining in the beaker is 157.26 grams - 154.34 grams = 2.92 grams. Or were they interested in determining the weight of the beaker??? Water has an approximate density of 1 g/mL, so you could even figure out that the beaker weighed 154.34 grams - 50 grams, or 104.34 grams. But there might have been something else to calculate (related to that "reaction" business!!).

Does this help??

Chris