How much does a liter of water weigh? The answer to a simple question

In response to the usual question "How much does a liter of water weigh?" Most people will offer to look in the directory or simply say: "One kilogram". And in fact, at a temperature of 40 ⁰ C and under conditions of normal atmospheric pressure, the weight of one liter Distilled, that is, devoid of any impurities, water is exactly 1 kg. And who can unequivocally answer the questions "How much does a liter of water weigh from a salt source?" Or "Which water is heavier - hot or cold?"

In order not to get into a mess, you need to familiarize yourself with some elementary laws of physics. For more specificity, it should immediately be stipulated that in this article we are not talking about the weight of water, but about its mass. The difference between these terms is that the mass is a fundamental indicator of the amount of matter, and it is measured in kilograms, and weight is a value indicating how much the body presses with a certain mass to the surface; Its unit of measure is Newton.

To answer the question about how much 1 liter of water weighs, first let's see what parameters the body weight is composed of. From the course of physics we know that mass is the product of Density of matter on the coefficient of acceleration of free fall, which is approximately the same on the entire surface of our planet and is equal to 9.81 kg / m ² . The oscillations of these two quantities give us a difference in the mass of the same substance under different conditions.

First, let's talk about the density of the liquid. As mentioned above, the density of clean water under normal conditions is 1000 g / m ³ . If it adds impurities, for example, salts, the density will increase, and the water will become heavier. As to the dependence of the mass of the object on temperature, here it is all a matter of the property of substances with heating to expand. This means that the distance between molecules becomes larger, and their total number per unit volume decreases, hence, the substance becomes lighter. However, water has a unique property - it expands not only with heating, but also with cooling (it is because of this that the water pipes burst in winter). The greatest density of water is at the freezing point, with the slightest deviation of the thermal scale, it becomes easier. How much does a liter of water weigh at different temperatures, if desired, you can look in the directory.

Atmospheric pressure does not affect the fluctuations in the mass of the fluid as much as Temperature, and the result of its impact is reversed by the action of high temperatures. When the pressure is high, the distance between the molecules decreases, hence a larger amount of matter will enter the same volume. As a result, there is an increase in mass. This can be easily verified in practice if we weigh the compressed air cylinder and the same cylinder with air at normal pressure.

By the way, do you know how much a liter of water weighs on the pole? 0.5 percent more than at the equator. This phenomenon is due to the rotation of the Earth around its axis. Because of it, the centrifugal acceleration increases as we approach the equator and, consequently, the acceleration of gravity increases .

Reasoning in this way, it is possible to calculate how much a liter of any liquid weighs, and how this index will vary depending on environmental conditions.