WEBVTT

1
00:00:00.000 --> 00:00:03.657
Here is the problem: What is the molar mass of CaCO3?

2
00:00:04.107 --> 00:00:10.063
Add the atomic weights of all 5 atoms in one formula unit of CaCO3.

3
00:00:10.863 --> 00:00:20.871
Count the atoms of each element. Subscripts multiply everything inside the brackets before them, and a hydrate coefficient multiplies the whole water (or other) unit.

4
00:00:21.321 --> 00:00:28.519
Look up each atomic weight (g/mol). IUPAC standard atomic weights (abridged, conventional values).

5
00:00:28.969 --> 00:00:31.918
Multiply each count by its atomic weight.

6
00:00:32.368 --> 00:00:33.842
Add the contributions.

7
00:00:34.642 --> 00:00:36.407
Mass percent of each element.

8
00:00:37.207 --> 00:00:43.558
So the answer is M(CaCO3) equals 100.086 g/mol.

9
00:00:44.008 --> 00:00:55.595
The molar mass is the mass of one mole of formula units. It equals the sum of the atomic weights of every atom in the formula, and numerically matches the formula mass in daltons (u).

10
00:00:56.395 --> 00:01:00.470
Percent composition adds to 100.00 percent.

11
00:01:00.920 --> 00:01:06.098
Elements: calcium times 1, carbon times 1, oxygen times 3.