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Density of Water

We observe in our daily life that objects like wood always float in water and it depends on size of these types of objects. This gives the effects of mass and volume on density. A physical property of matter is density which is unique quantity for each element and compound. It is defined as the measurement of the heaviness of objects at a constant volume in qualitative manner; for example; a rock is heavier than a crumpled paper piece of the same size. Similar a ceramic cup is denser than styro-foam cup. This physical quantity also is referred as how closely packed material. 

The less dense object than water is float on water like wood, ice floats on water due to its less density than water. Similar oil floats on the mixture of vinegar and water. It is mass per unit of volume and expressed as grams per mL or cc. Here we are discussing the density of water at different temperature and in different types of water like in salted water, sea water, pure water, water vapour.

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What is the Density of Water?

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Density is a measure of the amount of substance in a certain space. Let us consider a bucket full of water, all the water molecules as a whole will be having fixed mass and let us consider the volume of the cylinder in which the water is filled.
We know that Density is given by:
Density of water = $\frac{Mass}{Volume}$
So, if we divide the mass of the water by its volume of the bucket, up to which the water is filled. We get its density. Instead of doing so let us consider unit volume of space in which water is filled. If we again divide mass by its volume we get the same Density at same temperature.
Thus, Density of water is independent of volume but depends on temperature. The density can be expressed as kg/m3 or gram per cubic meter. We can also call the Density of Water as Mass Density of Water as mass is playing a major role here.

Densities of water at various temperature scales:

Sl no
Temperature in 0C
Density in Kg/m3
1 100 958.4
2
80 971.8
3 60 983.2
4 40 992.2
5 30 995.65
6 25 997.04
7 22 997.77
8 20 998.2
9 15 999.1
10 10 999.70
11 4 998.97
12 0 999.83
13 -10 998.12
14 -20 993.547
15 -30 983.854

Use below widget to calculate the water density.

Density of Different Types of Water

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1. Density of Salt Water


Let us collect equal amount of river water and sea water. Now, find its density. We will find that the density of river water is different from that of ocean at a constant temperature. Why is it so?

We know that the density of water remains same at constant temperature. Still why the density is varying in both these waters?
We know that sea water has salt content present in it. So, another component to be considered is salt content in water. It is actually salt that adds more mass to the water, which makes the water denser. It is the only reason for which there is still ice floating in the oceans and not all frozen up. The salt that is present actually lowers the freezing point of water. It also affects the density of water. Water with salt in it is basically denser than the normal freshwater. Hence, it tends to sink down the ocean.

The density of salt water may range from 1020 to 1030 kg/m3 but it may vary with the amount of salt present in water and the temperature.

2. Density of Sea Water


The Density of Salt Water may range from 1020 to 1030 kg/m3 but it may vary with the amount of salt present in water and the temperature. The dissolved salts actually add more to the mass of water than its volume and hence are denser than the normal water.
As the amount of salt content will increase the freezing point of water would reduce eventually. The known density of surface sea water is from about 1020 to 1029 kg/m3.
If we go deep in sea, then the density of water changes to 1050 kg/m3.

The salt that is present actually lowers the freezing point of water. It also affects the Density of Water. Water with salt in it is basically denser than the normal freshwater. Hence, it tends to sink down the ocean.

The weight of water divided by per unit of its volume is called the density of water. Basically the weight of water in the unit volume of it is the density of water. The density of water is related to the temperature at which water is when its density is measured.
The density of sea water lies between 1,020 to 1,029 kg/m3. If we go deep in sea then the density of water changes to 1050 kg/m3.

3. Density of Water Vapor


The Density of Water Vapor can be written as:
$\rho$ w = 0.0022 $\frac{P_{w}}{T}$
Here Pw is the Partial pressure water vapor. It is expressed in N/m2.
$\rho_{w}$ is density water vapor expressed in kg/m3.
T is the temperature of absolute bulb also called absolute bulb temperature expressed in Kelvin.
The density of water is related to the temperature at which water is when its density is measured.

4. Density of Liquid Water


The density of liquid water is 1000 kg/m3. The objects or material whose density will be lower than this will flow on water. If the density is higher than this value the object will sink in.

5. Density of Pure Water


The Density of pure water is 1 gm/cc or 1 gm/ml. The specific gravity is 1. It is important to know that density has units while specific gravity has none. The important factor which adds density to the water is the salt present in it. Salty water is denser than pure water due to the presence of salt content. The density of salt water may range from 1020 to 1030 kg/m3 but it may vary with the amount of salt present in water and the temperature.
The dissolved salts actually add more to the mass of water then its volume and hence are denser than the normal water. As the amount of salt content will increase, the freezing point of water would reduce eventually. The known density of surface sea water is from about 1020 - 1029 kg/m3.

6. Density of Distilled Water


The Density of distilled water is same as that of pure water as it does not contain any impurities or salt content in it. The density of distilled water is 1 g/cm3, 1 kg per litre, 1 tone per m3 or one gram per ml.

7. Density of Tap Water


The Density of tap water is 1 gram/cm3 and 1 gram per milliliter. It should be noted that mostly all the densities are the same. They differ in only points but the approximate values are used in calculations.

Density of Water at Room Temperature

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Room temperature is considered to be $25^{\circ}$ c. The density of water at room temperature is equal to 997.77 Kg/m3or 0.9970 g/cm3.
When the temperature is 4 degrees, then the density of water is considered to be maximum. The reason due to which ice floats on water is that ice is less dense as compared to water. The density can be expressed as kg/m3 or g/m3.

Density of water at 20°C

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We know that density varies with temperature. Hence every temperature has its own density.The Density of water at $20^{\circ}$ C is 1 gm per cubic centimeter or 1 gm per milliliter. This is the rounded up or approximate value. The actual density is 0.9982071 gm/cm3.

Density of Water at 25°C

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The temperature $25^{\circ}$ C is generally taken as standard room temperature even though room temperature varies from 20 - 30$^{\circ}$ C. The Density of water at $25^{\circ}$ c is 0.998 gm/ml.

Density of Water g/cm3

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In SI system, the units of Density of Water are kilograms per cubic meter. In CGS system they are expressed in gram per cubic centimeter. The density of water in g/cm3 is one.
The various densities at different temperature are expressed which represents the Density of Water Table as given below:

Sl no
Temperature
Density in gm/cm3
1 100 0.9584
2 80 0.9718
3 60 0.9832
4 40 0.9922
5 30 0.9956
6 25 0.997
7 22 0.9978
8 20 0.9982
9 15 0.9991
10 10 0.9997
11 4 0.99997
12 0 0.9998
13-100.9981
14-200.9935
15-300.9838

Density of Ice

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We know that ice is a crystalline solid made of water. So, there lies a question, will both ice and water have the same density? If not which one is denser Water or Ice and why?

Ice is less dense than water
: As water cools and becomes a solid (freezes), hydrogen bonds form between the water molecules. This is a covalent bond which leads to interconnected solid pattern. There is much more space between each molecule due to Hydrogen Bonds which makes the Ice less denser compared to water.

The density of Ice is 0.9167 gm/cm3 and the density of water is 0.9998 gm/cm3.

How Many Pounds Does One Gallon of Water Weigh?

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Gallon is defined as the weight of water. It is also called weight density. Here is the Weight Density of Water at different temperatures.

Temperature
Density in lb/m3 Density in lb/gallon
32 62.41
8.344
40 62.43
8.345
50 62.41 8.343
60 62.37 8.338
70 62.31 8.329
80 62.22 8.318
90 62.12 8.304
100 62.00 8.288
110 61.86 8.27
120 61.76 8.25
130 61.55 8.228
140 61.38 8.205
150 61.19 8.18
160 60.99 8.154
170 60.79 8.126
180 60.57 8.097
190 60.34 8.067
200 60.11 8.035
220 59.61 7.969
240 59.08 7.898
260 58.52 7.823
280 57.92 7.743
300 57.31 7.661
350 55.59 7.431
400 53.65 7.172
450 51.47 6.88
500 48.95 6.543
550 45.96 6.143
600 42.3 5.665
650 37.4 4.999
700 27.3 3.651

We know that 1 feet = 0.3048 m. Thus, using this relation, we can find the Density of Water in lb/ft3 by converting meters in to feet.

Specific Density of Water

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The Specific weight per unit volume is called the Specific density of water. The specific density of water is 1 gm/m3. The difference is that the specific weight is used instead of mass. Rest the process of calculation is the same.

Average Density of Water

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The Average density is the ratio of Average of all masses to its Average volume.

It is given by
Average density = $\frac{Average\ Mass}{Average\ Volume}$It is expressed in Kg/m3.
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