Density of Water

Understanding the Density of Water

If you are reading this article, then you are probably wondering what is the density of water?

Usually, it is roughly 1 gram per milliliter. But, keep in mind that a change in the temperature can alter the water density. 

With that, it is given much more importance as compared to water measurement. 

For this guide, we would further discuss water density, why it is important, as well as other information you should know.

Water Density

Before we look at the density of water, let us first briefly discuss what density is. 

Density is simply the measure of mass per volume. The equation looks like this

d = mv

d = density

m = mass

v = volume

To help you put this equation into perspective, let us take a look at the picture below

Density of Water

If you solve for an object density and the result is greater than 1, then that object would automatically sink in water. 

One of the most popular examples usually used in school is oil and water to explain density.

Oil is less dense than water (below 1) so it is no wonder why it floats on water. 

Density of Water

As we have pointed out before, the temperature can alter the density of water. So when you boil water, it would slightly get lighter.

If you look at the table below, you would see that the weight and density of the water slightly change as temperature changes. 

The water density table below is from metrologia

Temp./ CDensity/ (kg m–3)Uncertainty / (10–3 kg m–3 )Relative densityUncertainty/10–9
0999.84280.840.999 867 87292
1999.90170.840.999 926 70056
2999.94290.840.999 967 95630
3999.96720.840.999 992 20912
4999.97490.840.999 999 9980
5999.96680.840.999 991 8339
6999.94310.840.999 968 19717
7999.90450.840.999 929 54724
8999.85130.830.999 876 31731
9999.78390.830.999 808 92037
10999.70270.830.999 727 74544
11999.60810.830.999 633 16451
12999.50050.830.999 525 53257
13999.38010.830.999 405 18362
14999.24740.830.999 272 43766
15999.10260.830.999 127 60070
16998.94590.830.998 970 96272
17998.77780.830.998 802 79974
18998.59840.830.998 623 37775
19998.40790.830.998 432 94775
20998.20670.830.998 231 75175
21997.99500.830.998 020 01976
22997.77300.830.997 797 97276
23997.54080.830.997 565 81977
24997.29880.830.997 323 76478
25997.04700.830.997 071 99880
26996.78570.830.996 810 70882
27996.51510.830.996 540 07083
28996.23530.830.996 260 25585
29995.94650.830.995 971 42686
30995.64880.830.995 673 73988
31995.34240.830.995 367 34589
32995.02750.830.995 052 38890
33994.70410.840.994 729 00793
34994.37240.840.994 397 33699
35994.03260.840.994 057 503108
36993.68470.840.993 709 630124
37993.32900.850.993 353 838147
38992.96540.860.992 990 241177
39992.59410.870.992 618 947214
40992.21520.880.992 240 065260

Ice is denser than water

Even though ice is the solid-state of water, it is less dense than liquid water. 

Density of Water

In the picture above, ice floats in water. 

As we glossed over a few times, water temperature alters the water density. So when the water froze and turns into ice, it becomes denser as compared to when it was in its liquid state. 

How does salinity affect water density?

Salinity is the saltiness of the water.

It affects the density of the water because mass also increases every time you put salt in it. 

By simply referring to the formula we cited before, we can already infer that salinity does affect water salinity. 

d = mv

Based on the equation, any changes in mass or volume would affect the density. 

So every time you put salt in water, you are also adding to its mass, which in turn would alter the water density. 

Water becomes heavier every time you put salt in, and the more salt you put in it, the more saline it becomes. 

Measuring Density

Apart from the equation we cited above, there are other ways to measure density and you can even use tools for convenience and more accurate measuring. 

Hydrometer

A hydrometer measures the density of liquid based on the concept of buoyancy. 

Its measuring principle is quite simple and straightforward. 

You would simply insert the glass body into the sample and it would then float at a certain level due to the mass of the hydrometer itself as well as the buoyancy. 

The depth of flotation would then determine the density of the liquid. 

So if you put a hydrometer in liquid like alcohol, kerosene, or gas, it would then sink deeper because these are low-density liquids. 

Keep in mind that aside from its usual specific gravity values, a hydrometer can also be calibrated to 

  • Baume
  • Brix
  • Alcohol
  • API (American Petroleum Institute Index) 

Pycnometers

Another tool that would help you measure the density of a liquid is pycnometers.

A pycnometer is usually made up of glass and a ground stopper. The density is calculated based on this formula Density = (M2 − M1)/Flask Volume.

Keep in mind that most pycnometers are calibrated for use in certain temperatures. With that, measurement is only valid at that certain temperature. 

You would then have to make sure that your sample is always equilibrated to the calibrated temperature of the pycnometer. 

Density chart for different elements

The data below is from Harper College’s website

Element (symbol)#Massdensity
Hydrogen (H)11.010.00009
Helium (He)240.00018
Lithium (Li)36.940.53
Beryllium (Be)49.0121.85
Boron (B)510.812.34
Carbon (C)612.0113.51
Nitrogen (N)714.010.00125
Oxygen (O)8160.00143
Fluorine (F)9190.00169
Neon (Ne)1020.180.0009
Sodium (Na)1122.990.97
Magnesium (Mg)1224.311.74
Aluminum (Al)1326.982.7
Silicon (Si)1428.092.33
Phosphorous (P)1520.971.82
Sulfur (S)1632.072.07
Chlorine (Cl)1735.450.00321
Argon (Ar)1839.950.00178
Potassium (K)1939.10.86
Calcium (Ca)2040.081.54
Scandium (Sc)2144.963
Titanium (Ti)2247.884.5
Vanadium (V)2350.946
Chromium (Cr)24527.2
Manganese (Mn)2554.947.2
Iron (Fe)2655.857.9
Cobalt (Co)2758.938.9
Nickel (Ni)2858.968.9
Copper (Cu)2963.558.9
Zinc (Zn)3065.397.1
Gallium (Ga)3169.725.9
Germanium (Ge)3272.615.35
Arsenic (As)3374.925.73
Selenium (Se)3478.964.81
Bromine (Br)3579.93.12
Krypton (Kr)3683.80.0037
Rubidium (Rb)3785.471.53
Strontium (Sr)3887.622.6
Yttrium (Y)3988.914.47
Zirconium (Zr)4091.226.44
Niobium (Nb)4192.218.57
Molybdenum (Mo)4295.9410.22
Technicium (Tc)43-98
Ruthenium (Ru)44101.0712.41
Rhodium (Rh)45102.9112.4
Palladium (Pd)46106.4212.26
Silver (Ag)47107.8710.5
Cadmium (Cd)48112.418.65
Indium (In)49114.827.3
Tin (Sn)50118.717.28
Antimony (Sb)51121.766.68
Tellurium (Te)52127.66.25
Iodine (I)53126.914.93
Xenon (Xe)54131.290.00589
Cesium (Cs)55132.911.88
Barium (Ba)56137.3273.51
Lanthanum (La)57138.916.15
Cerium (Ce)58140.166.77
Praseodynium (Pr)59140.917.26
Neodynium (Nd)60144.246.8
Promethium (Pm)61-1457.26
Samarium (Sm)62150.367.52
Europium (Eu)63151.975.25
Gadolinium (Gd)64157.257.9
Terbium (Tb)65158.938.23
Dysprosium (Dy)66162.58.55
Holmium (Ho)67164.938.8
Erbium (Er)68167.269.07
Thulium (Tm)69168.939.32
Ytterbium (Yb)70173.046.97
Lutetium (Lu)71174.979.84
Hafnium (Hf)72178.4913.3
Tantalum (Ta)73180.9516.63
Tungsten (W)74183.8519.3
Rhenium (Re)75186.2121
Osmium (Os)76190.222.6
Iridium (Ir)77192.2222.4
Platinum (Pt)78195.0821.4
Gold (Au)79196.9719.3
Mercury (Hg)80200.5913.6
Thallium (Tl)81204.3811.85
Lead (Pb)82207.211.3
Bismuth (Bi)83208.989.8
Polonium (Po)84-2099.32
Astatine (At)85-210
Radon (Rn)86-2229.76
Francium (Fr)87-2232.4
Radium (Ra)88226.035
Actinium (Ac)89227.03
Thorium (Th)90232.0411.5
Proactinium (Pa)91231.04
Uranium (U)92238.03
Neptunium (Np)93237.05
Plutonium (Pu)94-244
Americium (Am)95-243
Curium (Cm)96-247
Berkelium (Bk)97-247
Californium (Cf)98-251
Einsteinium (Es)99-252
Fermium (Fm)100-257
Mendelevium (Md)101-258
Nobelium (No)102-259
Lawrencium (Lr)103-260

Practice Problems

Using the equation and the information we discussed above, try to answer some of these practice problems from Carleton College’s website. 

Problem 1: You have a rock with a volume of 15cm3 and a mass of 45 g. What is its density?

Problem 2: You have a different rock with a volume of 30cm3 and a mass of 60g. What is its density?

Problem 3: In the above two examples which rock is heavier? Which is lighter?

Problem 4: In the above two examples which rock is more dense? which is less dense?

Problem 5: You decide you want to carry a boulder home from the beach. It is 30 centimeters on each side, and so has a volume of 27,000 cm3. It is made of granite, which has a typical density of 2.8 g/cm3. How much will this boulder weigh?

Problem 6: Rocks are sometimes used along coasts to prevent erosion. If a rock needs to weigh 2,000 kilograms (about 2 tons) in order not to be shifted by waves, how big (what volume) does it need to be? You are using basalt, which has a typical density of 3200 kg/m3

Problem 7: A golden-colored cube is handed to you. The person wants you to buy it for $100, saying that is a gold nugget. You pull out your old geology text and look up gold in the mineral table, and read that its density is 19.3 g/cm3. You measure the cube and find that it is 2 cm on each side, and weighs 40 g. What is its density? Is it gold? Should you buy it?

You can view the answer here

Conclusion

Now that you know and understand what water density is, we highly suggest you conduct some experiments at home so that you can apply and better grasp the things you just learned. 

You can try some simple experiments and observations like mixing oil and water, put ice cubes in warm water, and so on. 

We find that applying and observing the things you just learned helps you better understand and grasp what it truly is.

With that, we hoped we managed to clearly explain what is water density as well as some of the other topics we covered like 

We have also discussed a few topics that we thought are relevant for your grade level such as

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Todd VanDuzer

Co-Founder & CEO at Student-Tutor
Hello! My name is Todd. I help students design the life of their dreams by ensuring college, scholarship, and career success! I am a former tutor for seven years, $85,000 scholarship recipient, Huffington Post contributor, lead SAT & ACT course developer, host of a career exploration podcast for teens, and have worked with thousands of students and parents to ensure a brighter future for the next generation. I invite you to join my next webinar to learn how to save thousands + set your teenager up for college, scholarship, and career success!
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