Density Lab



Density Lab-Pre Lab

(Chemistry)

Name: Partner:

Introduction: Density is the ratio of an object's mass to its volume. Gold has a density of 19.3, the average rock has a density of 2.4-3.0, and water has a density of 1.00 g/mL. 1.00 g/mL means that 1.00 mL (or cm3) of water has a mass of 1.00 gram or 1.0 Liter of water has a mass of 1.0 kg.

You will be finding the density of a unknown liquid and 3 solids. The masses will be found on a balance. The volumes will be calculated from the radius and the height [( r2 h] (cylinder) or length x width x height [l x w x h] (rectangular solid) or determined by submerging in water (displacement).

Don't forget when reading the graduated cylinder to read the bottom of the meniscus as shown below.

[pic]

  

Pre-lab questions:

1. Which is more dense, a marshmallow or hot chocolate?

a) It depends on how much you have

b) The marshmallow because it floats

c) The hot chocolate because it is a liquid

d) The marshmallow because it weighs 25g and the chocolate powder only 17 g

2. Which is denser, water or oil, why?

 

3. What mass does 3.0 mL of gold have?

Density Lab – An Intrinsic Property of Matter

D = m/V

Procedure: Part I & II will be completed on Day 1. Part III & IV will be completed on Day 2.

Part I: (Liquid)- 1. Place a 10 mL graduated cylinder on the balance and record its mass.

2. Put exactly 5-7 mL of an unknown liquid into the cylinder and find its mass again.

3. Record your data in your data chart including the exact volume you used?

4. Calculate the density of the liquid.

Part II: Solids (Irregular shape) [Volume by displacement] - 1. Place the irregular shaped object on the electronic balance and record its mass in your data table.

2. Place approximately 5 mL of water into a 10 mL graduated cylinder. Record the exact amount in your data table. (Make sure the object will be completely covered by the water)

3. Gently place the object into the cylinder and record the new volume. The difference between the two volumes is the volume of the irregular solid.

4. Calculate the density of the irregular shaped object.

Part III: Solid (Rectangular solid) - 1. Place the block on the balance and record its weight.

2. Measure its length; width and depth (height) in cm. then calculate the volume of the rectangular solid.

3. Calculate the density of the unknown solid.

Part IV: Solid (Cylindrical solid) - 1. Place the block on the balance and record its weight.

2. Measure its diameter and height in cm. then calculate the volume of the cylindrical solid.

3. Calculate the density of the unknown solid.

 Name: Partner:

Data:

Part I:

|Mass of Graduated Cylinder |g |

|Mass of Graduated Cylinder and Liquid |g |

|Mass of Liquid |g |

|Volume of Liquid |mL |

|Density of Liquid |g/mL |

Part II:

|Mass of Object |g |

|Initial Volume of Liquid |mL |

|Final Volume of Liquid and Solid |mL |

|Volume of Solid |mL |

|Density of Solid |g/mL |

Part III: Color of Solid:

|Mass of Solid |g |

|Length of Solid |cm |

|Height of Solid |cm |

|Width of Solid |cm |

|Volume of Solid (V = l x w x h ) |cm3 |

|Density of Solid |g/cm3 |

Part IV: Color of Solid:

|Mass of Object |g |

|Radius of solid |cm |

|Height of solid |cm |

|Volume of Solid (V = ( r2 h ) |cm3 |

|Density of Solid |g/cm3 |

Calculations:

Show Density calculations for Part I & II.

1. Part I:

2. Part II:

Calculations:

Show Volume and Density calculations for Part III & IV.

3. Part III:

4. Part IV:

 

Post-Lab Questions:

1. What would be the mass of 100cm3 of the metal that the cylinder is made of? – Show your calculation

2. Find a chart of the densities of common metals and figure out what metal it is.

3. If oil has a density of .88 g/cm3, would it float on the liquid used in this lab? Why or why not?

4. Calculate the Percent Error for the metal used in Part IV using the formula below. Show all work. Express answers to correct number of significant figures.

% Error = (|error|/expected value) x 100

% Error

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