Chemistry Lab Report

Lab Report Marisa McKinney P. 2
Purpose: To investigate the periodic variation of density in Group 4A elements.
Background: When the elements are arranged in order of increasing atomic number, they exhibit periodic recurrence of properties. Elements in the same group in the periodic table tend to have similar physical and chemical properties. These similarities are due, in large part, to similarities among the electron configurations of the elements in a group. You can find periodic trends in certain properties, such as density, among the elements within a given group. In this experiment, you will investigate the variation in density among three Group 4A elements. You will use your results to predict the density of another Group 4A element.
Pre Lab Questions:
1. How are elements arranged in a periodic table?- Atomic number
2. What are the vertical columns in the periodic table called?- Periods
3. What determines whether two elements will have similar chemical properties? If they are in the same group
4. What property will you measure in this experiment?- Density
5. Describe how you will determine the volume of an irregularly shaped solid.- In a liquid
6. Describe how you will calculate density.- Mass/volume
7. In what periods can you find Pb, Sn, Si, and Ge?- Period 3
Materials:

Safety goggles
Apron
Water
100 ml graduated cylinder
Centigram balance
Lead
Silicon
Tin

Procedure:
1. Determine the mass of the samples to the nearest 0.01 gram. Record. 2. Fill a 100 ml graduated cylinder about three quarters full with water. Measure the volume, and record as “volume of water alone” in the data table. Tilt the cylinder and carefully slide one of the samples down the side. Make sure the sample is completely submerged in the water. Measure the volume and record as “volume of water + sample” in the data table. 3. Repeat step 2, using the other samples. 4. Dry the samples and return them to the container designated by the teacher. 5. Wash your hands thoroughly with soap and water.

Tin (Sn)
Lead (Pb)
Silicon (Si)
Mass of sample (g)
11.6
10.11
4.5
Volume of water alone (ml)
45
55
65
Volume of water + sample (ml)
48
37
62
Volume of sample (ml)
3
2
3
Density of sample (mass/volume)
3.86
5.055
1.5
Appearance
Rocky
Roll of tape
Rocky

Post-lab Questions:
1. Based on your graph, estimate the density of germanium, Ge. Compare your estimate with the accepted density of germanium which you will get from your teacher. Give possible sources of any errors.
2. Calculate the percent error between your estimated value and the accepted value for the density of germanium.
Percent error = (estimated (lab) value – accepted value)/ accepted value X 100 %
a. Lead 11.342 g/cm3 -10.86%
b. tin 7.265 g/cm3 -59.66%
c. silicon 2.336 g/cm3 -92.63%
d. carbon 2.266 g/cm3 - 3. Based on the data table, hypothesize about how density will vary among the elements in other groups in the periodic table.- In other groups, the density should be similar to each other like they show here.