What is the density of water? 

Have you ever wondered what the density of water is? If yes, you couldn't have chosen better. This article is a huge compendium about water density. What can you find in this article? First of all, density of water at standard conditions in different units. Moreover, we will tell you a little about water density at different temperatures and also show you how you can calculate density of subjects. Is it what you were looking for? Keep reading!

We will start with the basics. We want to explain you what the density is exactly. Here is the definition. The density of a substance is its mass per unit volume. The density is sometimes called the volumetric mass density or specific mass. So the density of water is its mass per unit volume.

The density of water depends on many factors. We want to tell you about the two main factors. First of these is the temperature of water. The second one is the salinity of water. When even one of these two factors changes, the density of water also changes.

We will tell you more about differences in density of water caused by changes in temperature or the salinity level in next parts of this article.

Now we want to show you the density of water in different units. Why? Because we know that in some countries are used different units than in another. This is a first reason why. The second reason is that sometimes it is needed to use another unit than you normally use. We want to make your life and calculations easier, so we gathered density of water in different units in one place. So let’s start.

Density of water lb/ft3

We will start with density of water lb/ft3. The density of water in these units are used very common. Before we give you a value of water density in lb/ft3 we want to tell you a little about these units.

Lb is a short for a pound. Pound, as you may know, is a unit of mass. In turn, ft3 is a short for a cubic foot. It is a unit of volume. These two units are used mostly in the United Kingdom and United States. Both of them are base units in Imperial and US customary systems of measurements.

So what is the density of water lbs/ft3? The density of water lb/ft3 62.4.

Let’s move on to another units.

Density of water g/cm3

This time we want to show you density of water g/cm3. As in the previous example, we will start with some theoretical information about these two units. We are convinced that theory is needed to better understand this topic.

G is a short for a gram. It is a unit of mass from a metric system. It is used mostly in continental Europe. In turn, cm3 is a short for a cubic centimeter. It is, like a cubic foot, a unit of volume. One cubic centimeter is exactly volume of a cube of dimensions 1cm x 1cm x 1cm. Cubic centimeters are also used mostly in continental Europe.

So what is the density of water g/cm3? It is exactly 1 g/cm3. It is completely different result from the previous one.

Now we can move on to another units. To be honest, we have two more examples of density of water ahead of us.

Density of water g/mL

Second last example. This time we will show you density of water g/mL. So let’s start with some theory.

As you know from the previous example, g is a short for gram. If you want to remind yourself some information about this unit, please go back to the previous part of this article. On the other hand, mL is a short for milliliter. Milliliter is a unit of volume derived from liter. Milliliters are used mostly in continental Europe. One milliliter is equal to one gram but only when its measured in a maximal density, that is mean at 4°C (39.2°F).

So what is the density of water g/mL? As you may have guessed, it is exactly 1 g/mL.

So now let’s move on to the last example.

Density of water kg/m3

The last example is density of water kg/m3. Are you ready for a bit of theory? Let’s start.

Kg is a short for kilogram. Kilogram is a unit of mass, mostly used in continental Europe. It is a unit from SI system, that is from International System of Units. It is also thousand times bigger than gram. So what is m3? M3 is a short for cubic meter. Cubic meter is also used mostly in continental Europe. Moreover, cubic meter is derived from SI system. In comparison to cubic centimeter, cubic meter is million times bigger!

So what is the density of water kg/m3? It is exactly 1000 kg/m3.

For your convenience we gathered all these results in a chart. Thanks to this you can easily compare them and pick the best unit for you or make a conversion from one unit to another. You can find density of water lb/ft3 table and other units table down below.

Unit of density of water Value of density of water (pure water, 4°C/39.2°F)
lb/ft3 62.4
g/cm3 1
g/mL 1
kg/m3 1000

This was the density of water in four different units. We want to emphasize that all these numerical values are correct only for pure water and only at 4°C (39.2°F). We can say it is density of water lb/ft3 at standard conditions. To be honest, not only in lb/ft3 but in other units too.

We will tell you about density of water at different temperatures in the next paragraph. Now we want to show you how density of salt water looks but firstly we want to explain you what salt water is exactly. Salt water means seawater, that is water from a sea or ocean. The salinity of salt water oscillates around 3.5%.

So what is the density of salt water? Its density ranges from 1020 to 1029 kg/m3. The final result depends on temperature and salinity. Deep in the ocean the seawater can reach density of 1050 kg/m3 or even higher.

It is also possible to change a unit of density. For instance, we can say that density of salt water is about 1.020 g/cm3 and deep in the ocean the density of seawater can be equal 1.050 g/cm3 or more. Another example, this time density of salt water lb/ft3. It is equal about 63.9262316544.

Water density at different temperatures

We told you that density of water varies at different temperatures. It is time to explain you this topic.

As we mentioned, all previous results for pure water was calculated for 4°C (39.2°F). This time we want to show you how density of water changes at different temperatures. We will show you value of density of water from freezing point to boiling point. Water freezes at 0°C (32°F). In turn, water boiling point is 100°C (212°F).

We gathered all these results in a chart. We know that this form of showing the results is so much clearer than just text. But before we show you a table, we want to give you two examples.

What are we going to show you? These two examples will concern density of water at two most frequently-checked temperatures in Fahrenheit. So let’s start with the first one.

What is the density of water lb/ft3 at 60f, that means at 15.6°C? Water density at this temperature is equal 62.364 lb/ft3. Do you want to see the result in another unit? No problem, it is also equal 0.99898 g/cm3.

Another example. What is density of water lb/ft3 at 70f, that means at 21.1°C? Water density at this temperature is equal 62.3 lb/ft3. Do you need this result in another unit? Here you are. Water density at this temperature is equal 0.99796 g/cm3.

So now we can show you density of water chart. To be honest, we are going to show you two different charts. First for density of water in lb/ft3 and second for density of water in g/cm3.

Let’s start with chart for density of water in lb/ft3.

Temperature Density of water in lb/ft3
0°C/32°F62.421
10°C/50°F 62.4062
20°C/68°F 62.3148
30°C/86°F 62.1577
40°C/104°F 61.9441
50°C/122°F 61.6822
60°C/140°F 61.3785
70°C/158°F 61.0382
80°C/176°F 60.6651
90°C/194°F 60.2619
100°C/212°F 59.8294

Now have a look at table for density of water in g/cm3.

Temperature Density of water in g/cm3
0°C/32°F0.99989
10°C/50°F 0.99965
20°C/68°F 0.99819
30°C/86°F 0.99567
40°C/104°F 0.99225
50°C/122°F 0.98805
60°C/140°F 0.98319
70°C/158°F 0.97774
80°C/176°F 0.97176
90°C/194°F 0.9653
100°C/212°F 0.95837

As you can see, at all these temperatures density of water is not equal 1. At some temperatures, like 0°C (32°F), density of water is close to 1 but never reaches it.

Curiously, ice has lower density than water at 4°C (39.2°F). It means that ice is less dense than water. That’s why ice floats in a glass of water.

Now you know density of water at different temperatures se we can move to the last part of this article – that is calculation the density of a substance.

How to calculate the density of a substance

It will be the most practical part of this article. We will show you how you can calculate the density of a substance. What can you find in this part? Of course formula for calculating the density of a substance and also practical examples. So let’s start.

Here is a formula for calculating the density of a substance:

ρ = m/V

And here is an explanation – ρ is the density, m is the mass and V is the volume. A little tidbit – ρ is spelled rho, it is a Greek letter. 

So how you can use this formula? We will start with example for a regular object. This calculations will be simpler. Have a look:

For instance, let’s calculate density of a concrete block that weighs 24 kg and has measurements: 0.25m x 0.12m x 0.38m.

Firstly, you need to calculate the volume of this block. It is so simply. You have to multiply all measurements and that’s it. Let’s see:

V = 0.25m x 0.12m x 0.38m = 0.0114 m3

So now you can divide mass by calculated volume:

ρ = 25 kg/0.0114 m3 = 2192.98246 kg/m3

As you can see, this formula is not complicated. If you use a calculator, your calculations will take only a second.

Now we want to show you how you can calculate the density of an irregular object or liquid. The formula is the same. But how can you calculate volume of an irregular object or liquid? You can calculate it with a graduated cylinder. You can place an object or pour liquid in a graduated cylinder and then measure the volume of water it displaces.

According to the principle of Archimedes the volume of displaced water is equal to the volume of poured liquid or placed object.

When you have the volume of an irregular object or liquid you can use the same formula as in the case of the density of a regular object, that is:

ρ = m/V

For instance, piece of metal weighs 500 g and its displaces 250 mL of water. So let’s calculate the density of this piece of metal.

ρ = 500 g/250 mL = 2 g/mL

We hope that now you can easily calculate density of different regular objects, irregular objects or liquids.

We also want to tell you a little about special tool for calculating density of liquids without making any calculations on your own. What is it? This tool is a hydrometer. It looks similar to a thermometer. The hydrometer has a bulb at one end to make it floats.

How to use a hydrometer? Just lower the hydrometer in a liquid until it is floating on its own. Remember – do it gently and slowly. Then check where the liquid ends and read the number. It will be the density of this liquid.

The hydrometer will be the perfect tool for those of you who do not like calculating on your own. Checking the volume using the hydrometer can be also a good fun for children.

At the end we gathered for you the most important information in a nutshell. It can be a quick reminder too. Have a look:

  1. What is the definition of a density? The density of a substance is its mass per unit volume.
  2. Density of water at 4°C (39.2°F) in different units:
  3. Unit of density of water Value of density of water (pure water, 4°C/39.2°F)
    lb/ft3 62.4
    g/cm3 1
    g/mL 1
    kg/m3 1000
  4. What are the freezing and boiling point of water? Water freezes at 0°C (32°F) and boils at 100°C (212°F).
  5. What is a formula for calculating density of a substance? The formula is: ρ = m/V.

We hope that after reading this article topic of the density of water is clear for you. This article is a huge compendium about it. We are convinced that this article will help you in everyday life and also during preparation for school or uni tests.

Check also our other articles and see that math related topic can be explained in a very simple way.


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Published: 08/16/2020
Modified: 08/16/2020