What is a chemical mole?

Answer 1

In Chemistry, we measure things in u(unified mass), but this is really really really small. It is not a practical way to talk about things. (I mean, do you know what 3 u's looks like, cuz i don't) A man named Avogadro came up with a better system. He discovered how many atoms it takes to convert u's to grams. This way you can work with larger amounts than only a few atoms. It turns out that exactly 6.022 x 10 ^23 atoms will convert u's to grams.

So, let's first understand u's. These values are unique for each atom, molecule, compound etc.... For atoms, the magnitude (value) can be found on the Periodic Table. For example Cl is 35.45 u.

In context(questions):

1. How many ATOMS are in one mole of Chlorine? This is tricky only because there is extra information. A mole of any substance has the same number of atoms (6.022 x 10 ^23), because it is the conversion. The number of atoms in a mole doesn't ever change.

2. How many GRAMS ar in 2 moles of Chlorine? 70.90 grams. One mole contains 35.45, so two moles is twice that number, 70.90.

3. How many moles are in 90.0 grams of Cl? approx. 2.54 moles. This is backwards from the last question. Take the 90.0 grams and divide it by the number of grams in one mole (35.45).

My suggestion to you is that you should use conversion factors. If you can successfully do this you won't even have to understand why you are doing what you are doing. (Note: make sure you understand conversion factors first. The units must cancel. Any con. factor can be flipped)

Some useful conversion factors:

1 mole/ 6.022 x 10 ^23 atoms

#(off of Periodic Table)/ 1 mole

#in U's = # in grams so #in u /# grams

ECT..

Good Luck. This is a tough topic for a lot of Chemistry students.

Answer 2

A mole is basically an amount of something. In chemistry, a mole is known as a chemical mole. To figure out the weight of a mole, you figure out the molar mass.