Chemistry

Ms. Kurzenberger

Lab Report #2 – Density

Background All matter has mass and volume, which means it takes up space. The relationship between these values is the substances density, a characteristic of matter. A characteristic property can be used to identify elements or compounds. Density is defined as mass per unit volume of a substance. By accurately measuring the mass and volume of the liquids, the density is calculated. By accurately measuring the volume displacement of water and the mass of the metals (solids), the density is calculated. The following substances will be used in the experiments: water, ethanol, one unknown liquid, iron, aluminum, and one unknown solid.

Hypothesis By identifying the density of known liquids and solids, the unknow liquid and unknown solid can be identified by their density. Density of solids are higher than the density of liquids.

Section 1: Materials/Methods Containers: 50 mL graduated cylinder Materials: Water, Ethanol, Unknown Liquid Instruments: Balance

Section 1: Find the Density of Various Liquids (Experiments 1 and 2)

o Observation: Using the 50 mL graduated cylinder, the volume and mass were increased and measured for both water and ethanol (C2H5OH), and an unknown liquid.

o Lab Results: The density of water, ethanol, and the unknown liquid are 1.000, 0.7893, and 1.1100 respectively. Density of the unknown liquid provides the conclusion that the liquid is ethylene glycol.

Find the Density of Various Liquids Mass (g)

Experiment Total Volume (mL) Water Ethanol Ethylene Glycol

50 mL graduated cylinder 0.00 54.000 54.000 54.000

Add 10.00 mL 10.00 64.000 61.893 65.100

Add 10.00 mL 20.00 74.000 69.786 76.200

Add 10.00 mL 30.00 84.000 77.679 87.300

Density (g/mL) 1.0000 0.7893 1.1100

o Data Analysis: When water is increased by 10.00 mL, the result was an increase in 10.000 g. The mass increased equally with the volume. Ethanol when increased by 10.00 mL had less of an increase in mass than the water. Ethanol is less dense than water and will float. Alternatively, when ethylene glycol was increased by 10.00 mL an increase was observed at more than water. Therefore, ethylene glycol is denser than water and will sink.

Alexandra Opell CHEM 1110L

Ms. Kurzenberger

Section 2: Materials/Methods

Containers: 50 mL graduated cylinder

Materials: Water, iron (Fe), aluminum (AI), unknown metal

Instruments: Balance

Section 2: Find the Density of Various Metals (Experiments 3 and 4)

o Observation: Using the 50 mL graduated cylinder and an initial mass of 84.000 g and volume of 30.00 mL (water) add various metals to find water displacement and density of the solids.

o Lab Results: Iron has a density of 7.87 g/cm3 while aluminum has a density of 2.70 g/cm3. As the unknown metal was added in 10.00 mL increments, the density was calculated at 7.14 g/cm 3, which identifies the solid as Zinc.

Find the Density of Various Metals Total Volume (mL)

Experiment Total Metal (g) Mass (g) Iron Aluminum Zinc

50 mL graduated cylinder – 54.000 0.00 0.00 0.00

Add 30.00 mL Water (Initial) – 84.000 30.00 30.00 30.00

Add 5.00 mL 5.000 89.000 30.64 31.85

Add 5.00 mL 10.000 94.000 31.27 33.70 31.40

Add 5.00 mL 15.000 99.000 31.91 35.56 32.10

Add 5.00 mL 20.000 104.000 32.54 37.41 32.80

Add 5.00 mL 25.000 109.000 33.18 39.26 33.50

Density (g/cm3) 7.86 2.70 7.14

o Data Analysis: Aluminum is known to be lightweight, therefore seeing such a small density makes sense compared to iron. I ron is heavy and much denser, almost three times as dense as aluminum. The zinc had similar density to the iron but appears to be slightly less dense than iron.

Conclusions

By accurately measuring the mass and volume of a liquid and a solid, the data can be used to calculate density of the substance. Density is an identifying property and can be helpful to identifying an unknown liquid or solid. The density of solids substances appears to be denser than the liquid substances.

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