Hey Mrs. Johnson I'm having trouble with my Chemistry. It's something about calculating percent composition by mass. Can you help me please?
Of course I can help you! It's very simple once you get the hang of it! It only requires 3 steps.
Do you have an example problem from your homework?
Yes, let us use the compound Magnesium Chloride.
As we can see the board, we need to identify the formula for Magnesium Chloride. Using the period table, it is MgCl2.
Step 1: Determine the correct Formula
I know that part...
Step 2: Determine the molar mass of the compound
Next we need to see the Molar Mass of the compound by adding up the atomic mass of all elements respectively with how many of each atop there are.
1 atom of Mg has a mass of about 24.3 g/mol and 1 atom of Cl has a mass of 35.5 g/mol which when you multiply by two atoms will get you 71.0 g/mol. This gives a combined total of about 95.3 g/mol rounded.