You can find the density of water, or use water to find the density of an object, using a simple experiment involving mass and volume measurements.
Determining the Density of Water
The density of water is approximately 1 gram per milliliter (g/mL) or 1 kilogram per liter (kg/L) at 4°C (39°F). However, this changes slightly with temperature. ^1 To experimentally determine its density, follow these steps:
- Gather materials: You'll need a graduated cylinder to measure volume, a balance scale to measure mass, and a sample of water. [^2, ^3]
- Measure the volume: Carefully pour a known volume of water into the graduated cylinder and record the volume in milliliters (mL) or liters (L). ^1
- Measure the mass: Weigh the graduated cylinder with the water using the balance scale. Subtract the mass of the empty graduated cylinder to obtain the mass of the water. Record the mass in grams (g) or kilograms (kg).
- Calculate the density: Density is calculated using the formula: Density = Mass / Volume. Divide the mass of the water by its volume to find the density. The result will be expressed in g/mL or kg/L. [2, ^3]
Using Water Displacement to Find the Density of an Object
Water displacement is a useful method to determine the volume of irregularly shaped objects, which is then used to calculate their density.
- Gather materials: You will need a graduated cylinder, water, a balance scale, and the object whose density you want to determine.
- Measure initial water volume: Fill the graduated cylinder with a known volume of water and record it.
- Submerge the object: Carefully submerge the object completely in the water. Make sure no air bubbles are trapped.
- Measure final water volume: Record the new water level in the graduated cylinder. The difference between the initial and final water levels represents the volume of the object.
- Measure the mass of the object: Weigh the object using the balance scale.
- Calculate the density: Use the formula Density = Mass / Volume to calculate the density of the object. Remember to use consistent units (e.g., grams and milliliters). ^4
Example: An object weighs 50g. When submerged in a graduated cylinder, the water level rises from 50mL to 75mL. Therefore, the object's volume is 25mL. The density of the object is 50g / 25mL = 2 g/mL.
Factors Affecting Water Density:
- Temperature: The density of water is most dense at 4°C (39.2°F) and decreases as the temperature increases or decreases from this point. [^5, ^6]
- Dissolved substances: Adding dissolved substances like salt increases the density of water. ^7
