What is technical difference between Liter and Kilogram?

Answer 1

The basic answer is that a litre is a unit of volume and a kilogram is a unit of mass.

A litre defines how much space something takes up and mass defines how much substance is in an object.

It may help to think of a litre being equal to 1/1000 of a cubic metre, which is the actual definition of a litre. So if you have a cube measuring one metre along each side this cube would be equivalent to one cubic metre in volume, now imagine this cube being made up of 1000 separate and equally sized boxes. Each of these boxes is one litre in volume.

Mass on the other hand is the only base unit which is defined by a physical object, this object is a piece of alloy that weighs (on earth) one kilogram.

There is much confusion between weight and mass because in everyday use the are, to all intents and purposes, the same thing. However if you transport this mass to another place, such as the moon, the amount of substance there is the same as it is here, but if you put it on a set of scales they would read differently. So it has the same mass (amount of substance) but a different weight.

In addition a litre of water weighs (on earth) approximately one kilogram so people tend to equate a litre as being a kilogram. This is untrue of anything except water.

Imagine if you took two of those 1000 boxes from above. Fill one of them with water and one of them with hot molten lead. Both would be one litre but the mass or weight would be different. The water would have a mass of about one kilogram the lead would would have a mass of about eleven kilograms.