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Unknown 1
Unknown 2
Unknown 3 Introduction
Materials & Instructions

Density is a physical characteristic of a material,just like color or shape. Because the density of a substance is constant,it is often used in chemistry to determine the composition of an unknown material.Since density is calculated by dividing the mass by the volume of a liquid,it is not dependent on sample size.

A 10-ml sample should have the density as a 100-ml sample because the difference in mass will be proportional to the difference in volume.

When attempting to identify substances by their densities,there are many possible sources of error.Mathematical error,a scale or triple-beam balance that is not properly calibrated, or a dirty beaker can cause serious discrepancies in the calculation.

### Materials

• Three 100-milliliter(ml) beakers
• Scale
• Unknown liquid 1
• Unknown liquid 2
• Unknown liquid 3

### Instructions

1. Find the mass of each beaker in grams (g). Record the mass on Data Table 1.
2. Pour 50 ml of an unknown liquid into beaker 1. Repeat with two other unknown liquids in beakers 2 and 3.
3. Find the total mass of beaker 1 and the liquid in it. Record this measurement on Data Table 1.
4. Find the mass of the liquid in beaker 1 by subtracting the mass of the beaker from the total mass. Record your calculation on Data Table 1.
5. Repeat steps 3 and 4 with beakers 2 and 3.
6. Calculate the density of each liquid by dividing its mass by its volume (50 ml). Record the density of each liquid on Data Table 1.
7. Data Table 2 shows the densities of some common liquids. Use this table to determine the identity of liquids 1, 2, and 3.
Table Calculator
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Analysis
Answers
1. isopropyl rubbing alcohol; light corn syrup; vegetable oil.
2. Were your calculated values accurate? If not, calculate the percent error using the formula:
3. 4. Would the densities have been different if you only had 25ml of each liquid?.
5. How can knowing the density of a liquid be useful?.
1. Could be restricted to Teacher version depending on client requirements and activity access – separate student and teacher accounts?