The lightest of the chemical elements, an indispensable component of organic substances, a necessary part of the molecules of life - water - and it's all about hydrogen. His very name was translated into Russian by converting parts of the Greek word - "giving birth to water." Hydrogen as a gas is a rather capricious and dangerous substance (it ignites!). And hydrogen in atomic form is very active and has reducing properties. Therefore, in chemical problem books, a student may be asked to determine what is the molar mass of hydrogen. This question can baffle even adults who have forgotten chemistry.
Specify what you mean
The very concept of "hydrogen" from a logical point of view is ambiguous. It can mean both hydrogen atoms and the corresponding gas that exists in molecular form. In the second case, it is a combination of two atoms. Most likely, the concept of “molar mass of hydrogen” refers to a gas, since the concept of atomic mass is more likely used for individual atoms. But also infree form hydrogen can exist, especially in some physico-chemical processes. And a mole of this substance has mass. So every time you solve a problem, be specific about what you mean.
Free atom
If you mean an atom, then the molar mass of hydrogen is one gram per mole. It can be converted to kilograms per mole, to comply with the SI requirements, for this you just need to multiply 1 by 10 to the minus third power. Although these data will not be entirely accurate, because atomic weights are not integer values, but fractional ones.
How hard
But be careful - if you solve a problem in a physics textbook, you may encounter heavy forms of hydrogen that have a different molar mass. The most common hydrogen is called protium and its mole weighs one gram, but there is also deuterium (2g per mole) and tritium (3g per mole). Deuterium is found in very small quantities (less than 0.2%) on Earth, and tritium is almost never found at all, but it is easy to obtain in nuclear reactions. In the process of solving real problems, physics and chemistry are not distinguished, so if you are preparing for a career in the natural sciences, you must be prepared to determine the molar mass of hydrogen in such non-standard situations.
Calculations for molecular shape
If the problem refers to a gas, then you will need to multiply the atomic mass of hydrogen by two and assign the unit g per mole. Atomic units and grams per mole are equivalent numerically,but the former are used more in physics and the discussion of the properties of elements, and the latter in solving practical problems in chemistry. But even here you can be caught and asked about the mass of heavy hydrogen. By the way, be careful, sometimes you will not be expected to multiply 2 or 3 by two at all. There are hybrid forms, for example, deuterium with tritium (the molar mass of hydrogen in this case will be 2 + 3=5), or protium with deuterium (3), or tritium with protium (4). Therefore, think logically and add, not multiply, so as not to be mistaken with heavy molecules.
Interestingly, water containing heavy hydrogen is also called heavy. Problems with its production from heavy hydrogen can be difficult, and for this purpose, you may have to calculate what is the molar mass of hydrogen in your particular situation.
