Density Block Lab

In this lab, we explore the relationship between mass, volume, and density. Mass is the amount of matter in an object, and is measured in grams. Volume, measured in liters, is the amount of space an object occupies. Density is the amount of matter in a certain amount of space, or the mass per unit volume. Therefore, we see that there is a connection between these three terms.

density = mass/volume

Today, we are trying to find the mass of a plastic block, given its density. Our only tool is a ruler, which we can use to find the volume. Then we should be able to obtain the mass of the block using its density and volume.

Procedure:

1. After obtaining a plastic block and a ruler, my partner, Zoe, and I first measured the dimensions of the block. We did this by placing the block and ruler on the lab desk. Lining up a bottom corner of the block with the "0 cm" mark on the ruler (in photo below), we found measurements for all the sides and recorded them, taking significant figures into account.
2. Next, we multiplied the length, width, and height in order to find the volume of the block, again following the rules of significant figures.
3. Using the equation for density, we calculated the mass of the block.
4. Then, we asked our RTA, Rachel, to weigh the block for us.
5. Finally we calculated the percent of error. To find the percent of error, we subtracted our calculated (experimental) mass from the actual mass and divided the difference by the actual mass. Since our percent of error was less than 2%, we did not repeat this procedure.

Data:

density = 0.985 g/mL

length of block = 8.75 cm

width of block = 2.45 cm

height of block = 3.75 cm

volume = (l)(w)(h) = 80.4 mL

calculated mass = (80.4)(0.985) = 79.2 g

Conclusion:

This lab shows that the mass of a block can be estimated, using its density and volume. Although the actual mass of the block was not equal to our calculated mass, it was within 2% of error. The cause of this inaccuracy would most likely be the estimation of the block's dimensions. However, it is very difficult to record entirely accurate measurements, considering the significant figures permitted when using the rulers. In the future, if possible, perhaps the ruler should be even more specific in order to calculate a mass closer to the actual mass. Overall, this lab fulfilled its purpose, as we learned how to find the volume of a block, and use its density to ultimately calculate its mass.