CHEMISTRY 101: WHAT IS A ” MOLE “? HOW DOES THE QUANTITY DESCRIBED AS BEING A ” MOLAR ” QUANTITY CONNECT THE INVISIBLE SUBATOMIC WORLD TO THE VISIBLE WORLD?
A balanced chemical equation is representative of a chemical reaction ( RXN ). For example, water is known to be made of two hydrogen ions + one oxygen atom. A discussion of charges on isolated atoms is another topic altogether. Here, the focus will be on demystifying one of the most important topics in quantitative chemistry. Understanding the concept of a ” mole “, usually abbreviated ” mol ” is central to success in a chemistry lab.
Let’s take the following equation involving water into question. 2H + 0 = H20 ( charges on the ions are omitted for simplicity ). Let’s pretend that hydrogen ( +H ) and oxygen ( 0 ) are atoms that we can handle with our hands. It would be nice if we could use a quantity of material in the laboratory that would replicate the ratios of atoms that react in the subatomic world. Hydrogen will be referred to as ( +H ) from here on out. It is nice to begin with hydrogen because it is the simplest element. As a single atom, it consists of one atomic mass unit ( amu ). In nature, hydrogen is generally diatomic, but that is of no concern here.
An atomic mass unit ( amu ) has a mass of 1.66 times 10^-27 kilograms. In a laboratory, it would be more useful to allow a gram of hydrogen to represent a single amu of hydrogen. How many amu would have to be grouped together to make a gram of hydrogen? Well, since 1 gram is MUCH larger than 1 amu, we must divide 1 gram by 1 amu to obtain the multiple of amu contained in 1 gram.
Pretend for a second that a penny is invisible, but a dollar can be seen. If a dollar is divided by the relatively smaller value of a penny, the ratio obtained shows that a dollar is 100 times larger than a penny, so it takes 100 pennies to equal the value of a dollar. In the same way, dividing 1 gram by 1 amu tells how many amu are needed to make 1 gram. Since 1 amu = 1.66 times 10^-24 grams, 1 gram divided by 1 amu = 6.024 times 10^23 atoms. This amount of atoms is called a mole ( mol ).
One mole ( 6.024 times 10^23 multiple ) of 1 amu = 1 gram. What if, however, some atom is made up of two amu ? A mole of that atom would contain twice as much mass. Since a mole of 1 amu = 1 gram, a mol ( 6.024 times 10^23 multiple ) of an atom with a mass of 2 amu would weigh 2 grams.
100 pennies = $1.00 If pennies are grouped together in small packages containing 2 pennies, how much is 100 of these packages worth? $2.00 If you take a nickel and multiply it by 100, you’ll have $5.00 Here, the number 100 is akin to a mole in the world of chemistry.
The atomic mass of carbon is 12. This means that it is made of 12 amu. Therefore, a mole of carbon = 12 grams. Twelve pennies times 100 = $12.00 The 12 amu in a carbon atom ( 6.024 times 10^23 ) = 12 grams.
1 mole is 6.024 times 10^23 amu.
With an understanding of this topic, any student is well situated to use balanced equations and solutions of known molarity to solve a wide variety of problems.
https://www.chemteam.info/Solutions/Molarity.html
Q: How many molecules are contained in 1L of a 1M solution of substance with a molecular structure composed of 34 amu?
A: A 1M solution contains 1 mole / L. Therefore, ( 1 mole / L )( 1L ) = 1 mole. 1 mole of this particular substance has a mass of 34 g. Furthermore, 1 mole of ANYTHING contains 6.024 times 10^23 base units of an atom or molecule ( all in accordance to the number of amu the atom or molecular structure is comprised of ).
RENAISSANCE PHYSICS 