The lightest of chemical elements, an essential component of organic substances, a necessary part of life's molecules - 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 problems, a student may be asked to determine what the molar mass of hydrogen is. This question can be confusing even for adults who have forgotten chemistry.
Specify what is meant
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 term “molar mass of hydrogen” refers to gas, since the concept of atomic mass is more likely to be used for individual atoms . But hydrogen can also exist in free form, especially in certain physicochemical processes. And a mole of this substance has a mass. Therefore, every time you solve a problem, specify what exactly is meant.
Free atom
If an atom is meant, then the molar mass of hydrogen is equal to one gram per mole. It can be converted into kilograms per mole to comply with the SI requirements, for this you just need to multiply 1 by 10 in minus the third degree. Although these data will not be entirely accurate, atomic weights are not integer values, but fractional ones.
So heavy!
But be careful - if you solve a problem in a physics textbook, you may encounter severe 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 (2 g per mole) and tritium (3 g per mole). Deuterium in very small quantities (less than 0.2%) is found on Earth, and tritium is almost never found, but it is easy to obtain in nuclear reactions. In the process of solving real problems, physics and chemistry are not differentiated, 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 unusual situations.
Calculations for the molecular form
If the problem refers to 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 in discussing the properties of elements, and the latter in solving practical problems in chemistry. But here you can catch and take an interest in the mass of heavy hydrogen. By the way, be careful, sometimes you will not be expected to multiply 2 or 3 in two at all. Hybrid forms are found, 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, reason logically and add, rather than multiply, so as not to make a mistake with heavy molecules.
Interestingly, water that contains heavy hydrogen is also called heavy. The problems with its production from heavy hydrogen can be difficult, and it is for this purpose that you may have to calculate what the molar mass of hydrogen is in your specific situation.