Mass, Volume, and Density Lab

Purpose: The purpose of this lab is to discover some of the properties of mass, volume, and density, and to use them interchangeably. The lab itself consists of obtaining the densities of several substances via the identification and implication of their mass and volume in an equation. The substances in question are as follows: a piece of metal, two samples of soda – Pepsi and Diet Pepsi, and an M&M. My prediction is that the piece of metal that I chose is brass, that the sodas are the same density, and that the M&M will be more dense than water.

Data and Calculations: The formula for Density is D = m / V (Density equals mass divided by volume). These are the results for the metal’s calculations (Sample A):

Mass	57.01g.
Volume of water without sample	13mL
Volume with sample	20mL
Water displaced by object	20 – 13 = 7mL
Volume of object	7cm3
Density of object	8 x 10g / cm3

1 mL = 1 cm³

D = m / V

D = 57.01g / 7mL

D = 8 x 10 g / 1 mL

D = 8 x 10 g / cm³

The sample is brass.

These are the results for the soda measurements:

Pepsi is 9.83g, 10.5mL. D = 9.83g / 10.5mL = .936g / mL.

Diet Pepsi is 17.48g, 19mL. D = 17.48g / 19mL = .92g / mL.

These are the results for the M&M measurements:

Mass	0.85g.
Volume of water without sample	6mL
Volume with sample	6.5mL
Water displaced by object	.5mL
Volume of object	.5cm3
Density of object	1.7g / cm3

D = 0.85g / .5mL

D = 1.7g / mL

D = 1.7g / cm³

M&M class results:

1.7 1.7 .85 .88

.87 1.6 .85 .06

1.6 .0509 2 .9

.88 1.19 .88 1.72

Class Average: 1.11

Analysis:

1) Our percent error for the density of the metal is [(8.00 – 8) / 8.00] * 100% = 0%.

2) I think that measuring the dimensions of the metal samples and calculating would be less accurate than determining these volumes by water displacement, because the samples are cylindrical, and are difficult to measure exactly. Therefore, measuring them by means of water is quicker and more accurate. Additionally, measuring the dimensions of a solid may not always be possible, especially if the solid is very irregularly shaped.

3) I determined the density by finding out their mass and volume. To do this, I placed the graduated cylinder onto the scale, then I tared it, then I poured the liquid inside, measuring the mass and volume at the same time. Then I used the formula to figure out the density.

4) The class results for the M&M’s were both imprecise and inaccurate. Many people measured incorrectly, or did the wrong procedures at the wrong time. Thus, our results ranged from whole units to mere hundredths of a gram per cm³.

Results/Discussion: I have discovered many interesting things from this laboratory. From my data, I had discovered how to determine what a metal is by looking at its density, I had discovered that both Pepsi and Diet Pepsi are less dense than water, and that M&M density is slightly more than water. My answers for the last two experiments seem wrong, because regular Pepsi is actually denser than water. My answer also does not make sense, because of a demonstration that we were shown, in which clearly Pepsi sunk to the bottom of an aquarium filled with water, while Diet Pepsi floated at the top. I think an error that occurred is that we measured the weight of the soda wrong. We may have recorded it before it settled on a stable weight. Another error could have been that we had measured the volume inaccurately. The difference between the accepted densities is not great, so even 1 mL could have thrown us off. According to Ms. Paige, an M&M’s density should be .88g/mL³, but I disagree. If the M&M was less dense than water, it should have floated at the top of the graduated cylinder. However, it sunk to the bottom, displaced some water, and thus we were able to measure its volume. I think that an error that occurred is that our graduated cylinder is too inaccurate for such a small object. It only displaced what we thought was .5 mL of water, but had we used a more accurate container, then we may have gotten some different results. My hypothesis was correct for the metal sample, neither my hypothesis, nor my experiment confirmed the correct answer for the soda densities, and I am not sure if I confirmed my hypothesis for the M&Ms. This lab showed me how to determine the densities of objects – something that I could not do before. I think that this is important, since sometimes you need to know how dense something is to compare it to something else, and you can also find out a different component of the equation if you know two other ones – for example, if you know the density and the mass, you can find out the volume.