Density of Solids Lab



Density of Unknown Cubes

Objective: Use two methods, fluid displacement and volume formula, to calculate the density of four unknown cubes.

Background:

Density is the amount of matter an object contains in a specified amount of space. The units for density are usually written as g/cm3 (grams per cubic centimeter) for a solid material and written as g/mL (grams per milliliter) for a fluid.

There are two methods for calculating the density of a solid in this lab. Each method involves determining the volume and mass of the solid.

Method 1

Record dimensions with a ruler. Follow the volume formula for the given object.

Example: Volume of a cube = (length) x (width) x (height)

Vcube = lwh

= (lab values inserted into formula with units)

= answer with correct unit and significant figures

Method 2

Fill a graduated cylinder with a known amount of water. Then gently lower the object into the graduated cylinder, noting the water displacement in a graduated cylinder to determine how much space (or volume) the object occupies.

Then determine the mass of the object using a balance.

Procedure:

Use Method 1 and Method 2, from the above background, to calculate the density of each unknown cube.

Data:

Data Table 1

|Object |Length (cm) |Width (cm) |Height (cm) |Volume (mL) from graduated cylinder |Mass (g) |

| | | | | | |

| | | | | | |

| | | | | | |

| | | | | | |

Calculations:

Calculations Table

|Object |Volume (mL) or (cm3) |Density (g/mL) or (g/cm3) |

| | | |

| | | |

| | | |

| | | |

Sample Calculations:

Conclusions:

1) What are the units for density?

2) What does density mean?

Below is a table of metals and their densities.

|Metal |Density (g/cm3) |

|Brass |8.55 |

|Iron |7.66 |

|Lead |11.37 |

|Nickel |8.90 |

|Zinc |7.04 |

|Aluminum |2.64 |

|Uranium |18.97 |

3) Predict the identity of your unknowns based on the density you have calculated compared to the chart above.

|Unknown Metal |Identity of Metal |

| | |

| | |

| | |

| | |

4) With what precision can the meter stick be measured with?

5) How close were the densities of your unknowns to the accepted values found in the table on page 3?

Calculate the %error in your density calculations using the formula discussed in the pre-Lab discussion.

6) Why do some objects float and some objects sink? Be specific and provide examples!

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