Volume usually changes when a substance changes state. Substances also expand volume when warmed and shrink when cooled. Volume also changes when one substance dissolves in another.
We need a reliable way to measure the quantity of substances where we get the same measure for the same material even it the circumstances change. The variations in volume due to change in state, dissolving, and temperature changes suggest that volume is far from ideal as a reliable measure.
We are searching for a reliable method to measure materials. We know that volume often changes when a material melts. This experiment investigates if mass also changes during melting.
Considering the sensitivity and limits of your balance, find a small container with tight lid and some ice that fits inside. Find the Mass of the container and ice. Allow the ice to melt. Caution: If you try to speed the melting, some of the water often escapes causing experimental errors. Be PATIENT! Find the mass of the container and water after melting. What should be done it condensation forms on the outside of the container? Consider if this is water leaking though the container walls, or water that was not originally part of the experiment. Does the mass change significantly during melting?
Since no measurement is perfect, do the same experiment a number of times then use the average of all measurements that seem consistent and where no errors are apparent to reach a conclusion. Of course if a leak or spill occurs, those results should not be included. Taking the average will tend to remove small experimental errors due to the limitations of the equipment. But errors caused by flawed experimental procedures are usually not removed by averaging.
Make a histogram of your results to visualize any pattern in your measurements.
Record in your science journal the mass measurements, first in table format, then by constructing a histogram. Write a Formal Report if you need to earn credit.
Investigate if mass changes when water freezes. Caution: Leave a head of air in the container to avoid breaking the container when the volume of water increases.