Density is the amount of mass of an object in each unit volume (the amount of space occupied by the object). The unit of measurement for density is grams per milliliter (g/mL). Finding the density of water is quite easy, the formula is density = mass / volume.
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Part 1 of 2: Finding the Density of Water
Step 1. Gather the ingredients
To calculate the density of water, you will need a measuring cup, scale, and water. A measuring cup is a special container that has lines or gradations that allow you to measure the volume of a liquid.
Step 2. Weigh the empty measuring cup
To find density, you must know the mass and volume of the liquid. Use a measuring cup to get the mass of water, but you have to subtract the weight of the measuring cup to know that you're only measuring the mass of water.
- Turn on the scale and make sure it points to zero.
- Place an empty, dry measuring cup on the scale.
- Record the mass of the cylinder in grams (g).
- For example, let's say the weight of an empty measuring cup is 11 grams.
Step 3. Fill the measuring cup with water
It doesn't matter how much water you put in. Just make sure you record the right amount. Read the volume with the eye perpendicular to the cylinder and record the volume at the bottom of the meniscus. The meniscus is the fluid curve you see when you look at water with your eyes straight.
- The volume of water in the measuring cup is the volume you will use for the density calculation.
- Say you fill a measuring cup with a volume of 7.3 milliliters (mL).
Step 4. Weigh the measuring cup filled with water
Make sure the scale points to zero and weigh the measuring cup filled with water. Be careful not to spill water when weighing it.
- If you spill water, note the new volume and re-weigh the water-filled measuring cup.
- For example, let's say a full measuring cup weighs 18.3 grams.
Step 5. Subtract the weight of the full measuring cup from its empty weight
To get just the mass of water, you have to subtract the weight of the empty measuring cup. The result is the mass of water in the measuring cup.
In the example above, the mass of the measuring cup is 11 g and the mass of the measuring cup filled with water is 18.3 g. 18.3 g – 11 g = 7.3 g, therefore the mass of water is 7.3 g
Step 6. Calculate the density of water by dividing the mass by the volume
Using the formula density = mass/volume, you can determine the density of water. Enter the known mass and volume values and solve.
- Water mass: 7.3 g
- Water volume: 7.3 mL
- Density of water = 7, 3/7, 3 = 1 g/mL
Part 2 of 2: Understanding Density
Step 1. Determine the formula for density
Density is equal to the mass of an object divided by the volume, m, divided by the volume, v, of the object. Density is denoted by the Greek letter rho,. An object with a greater density will have a greater mass for a small amount of volume than an object with a smaller density.
The standard formula for density is = m/v
Step 2. Use the appropriate units for each variable
Calculating density usually uses metric units. The mass of an object is denoted by grams. The volume of an object is denoted by milliliters. You will also find volume in cubic centimeters (cm3).
Step 3. Know why density is important
Density of an object can be used to identify various kinds of substances. If you are identifying a substance, calculate its density and compare it to the known density of other substances.
Step 4. Know the factors that can affect the density of water
Even though the density of water is close to 1 g/mL, certain scientific disciplines need to know the density of water with a higher specification. The density of pure water changes with temperature. The density of water is inversely proportional to the temperature.
