Why calculate percent change in mass

The intention here is to determine molecular formulas, which are scalable. Therefore, in this case, the percent is a way to report the data in a more accessible manner without the need to specify the scale. Maybe you have to report the amount of intermediate product lost during a synthesis process? If you report the percent without the scale, you don't really know the significance of the loss of product. Furthermore, knowing the scale could help one rationalize how much larger of a scale would be practical , in terms of cost.

If you've lost a lot of product on a large scale, it would likely be a significant expense, and more importantly, it could detract from the viability of the synthesis process being efficient.

When might it be better to report percent changes in mass, instead of absolute changes in mass? Truong-Son N. The percent change in mass shows what proportion of a substance's mass has changed over time. For instance, if one-fourth of a rock's mass is worn away over a year, that rock's mass has a change of 25 percent. To calculate percent change in mass for an object, you need to know only its initial and final masses and simple multiplication and division.

To determine the percent change in an object's mass, you first need to know how much mass you had to begin with. Say you're conducting an experiment where you place water in a beaker and see how much evaporates over 24 hours.

You would begin by measuring the mass of the water, using a scale. First, you weigh the beaker without the water, and then weigh the beaker with the water in it. Subtracting the mass of the beaker from the mass of the water gets you the initial mass of the water. If your beaker has a mass of 0. After the 24 hours passes, you weigh the beaker with water in it again to see how the mass has changed.

Subtract the mass of the beaker you calculated at the beginning to determine the final mass of the water. If the beaker with water in it were to have a mass of 1. Once you have the initial and final masses of your substance, subtract to determine the difference. This simple calculation shows the amount the mass has changed. The investigation cannot be based on changes in mass from just one potato cylinder.

In scientific tests, we must ensure a number of examples are used to allow for anomalous results and variation. Percentage changes in mass must be calculated for each cylinder and mean calculated. A graph is plotted of change in mass, in per cent, against concentration of sucrose.

Concentrations of solutions are shown as percentages. A larger number means a higher concentration. Where potato cylinders have gained in mass, the change will be positive. Where potato cylinders have decreased in mass, the change will be negative. Where the plotted line crosses the horizontal axis at 0 per cent change in mass, the sucrose concentration of the solution is equal to the concentration of the contents of the potato cells. This can be identified on the graph as the point which shows no net movement of water by osmosis , which would be represented by a change in mass.

What is the concentration of solutes in the cells of the potato in this investigation?