Lab 1A: Density Block Lab

In this lab, the mass of a plastic block was found using its known density and measured volume. The mass of the block, determined by the equation mass = density * volume, is how much matter is in an object. The density, determined by the equation density = mass/volume, is how much matter is in a unit of space in an object. To find the volume of the block, or amount of space in it, the equation length*width*height can be used. After calculating the experimental mass, the actual mass was found using a scale, and the percent error was calculated. In this lab, we aimed for a <2% error.

Procedure:

1. We knew that the density of the plastic block to be 1.42 g/cm^3. The goal of the lab was to calculate the mass, so we needed to find the volume in order to solve the equation mass = density * volume. 
2. In order to find the volume of the block, we used a ruler to measure its length, width, and height. We estimated the length to be 7.50 cm, the width to be 3.25 cm, and the height to be 2.45 cm. 
3. We then plugged these values into the formula volume = length*width*height. 7.50*3.25*2.45 = 59.7188, but since the other values had three significant figures, we rounded to 59.7 cm. 
4. We then plugged this number into the equation as well as the known density, giving us the equation 1.42 g/cm^3 = mass/59.7 cm. 
5. To solve for mass, we multiplied 59.7 * 1.42 = 84.774 = mass, but since the values had three significant figures, we rounded to 84.8 grams.
6. We then brought the block to Ms. Kapinos and she measured its mass using the scale, finding the actual mass to be 85.1 grams.
7. In order to calculate the percent error, we used the equation percent error = ((actual-experimental)/actual) * 100, and plugged in the experimental mass as 84.8 g and the actual mass as 85.1 g in order to find the percent error of .353%.

Data:

• Block One
• density: 1.42 g/cm^3
• volume: 59.7 cm^3
• length: 7.50 cm
• width: 3.25 cm
• height: 2.45 cm
• experimental mass: 84.8 g
• actual mass: 85.1 g

Conclusion:

In conclusion, we found our experimental mass of the plastic block to be 0.3 g off of the actual mass, resulting in a .353% error. Since the purpose of the lab was to calculate the volume manually using a ruler and our knowledge of significant figures and then use that volume to calculate the mass of the block and get within a 2% error of the actual mass, we did fulfill the purpose of this lab. Possible error could be within the initial measurement of the sides of the plastic block. If the estimation was a few micrometers off, the volume could be affected, and therefore the mass could be affected. In the future, I would look more closely at the ruler and think about my estimation more.