Video Transcript
15 grams of table salt were
dissolved in an amount of water. The water was then evaporated,
leaving only the salt. How much salt remained?
The question tells us that 15 grams
of table salt were dissolved in an unspecified amount of water. Dissolving the salt in the water
produces a saltwater mixture. The mixture still contains the 15
grams of table salt and the water that was initially added. But we can’t see the individual
components. The question tells us that the
water is then evaporated. The question also tells us that
when the water was evaporated, only the salt remained. To answer the question, we need to
determine how much salt remained after the water was evaporated.
There are two important points that
we need to know. First, throughout this process,
only two compounds are present: water and table salt. Second, table salt does not
evaporate along with the water. So, when the water is evaporated,
all of the table salt remains in the container. As the table salt is not
transformed into a new compound during this process and the table salt does not
evaporate, when the water is removed, all 15 grams of the table salt should still be
present in the container. This follows the law of
conservation of mass, which states that mass cannot be created or destroyed. So, in this process, if the initial
mass of the table salt is 15 grams, then the final mass of the table salt must also
be 15 grams.
Therefore, the amount of salt that
remains when the water is evaporated is exactly 15 grams.
