Solution - Finding a molecular mass
Other Ways to Solve
Finding a molecular massStep-by-step explanation
1. Break down the molecule to its elements
The molecule PBO2 consists of:
1 Phosphorus atom
1 Boron atom
2 Oxygen atoms
| Element | Symbol | # of atoms |
| Phosphorus | P | 1 |
| Boron | B | 1 |
| Oxygen | O | 2 |
2. Identify the atomic mass of each element
The atomic mass is shown below each element on the periodic table.
PBO2 molecules consist of:
Phosphorus P=30.973762 u
Boron B=10.811 u
Oxygen O=15.9994 u
| Element | Symbol | Atomic mass | # of atoms |
| Phosphorus | P | 30.973762 | 1 |
| Boron | B | 10.811 | 1 |
| Oxygen | O | 15.9994 | 2 |
3. Calculate the total atomic mass of each element in a molecule of PBO2
P → 1·30.973762=30.973762 u
B → 1·10.811=10.811 u
O2 → 2·15.9994=31.9988 u
| Element | Symbol | Atomic mass | # of atoms | Total atomic mass |
| Phosphorus | P | 30.973762 | 1 | 30.973762 |
| Boron | B | 10.811 | 1 | 10.811 |
| Oxygen | O | 15.9994 | 2 | 31.9988 |
4. Calculate the mass of the molecule PBO2
30.973762+10.811+31.9988=73.783562
The average molecular mass of PBO2 is 73.783562 u.
5. Graph of molecular composition by atoms
6. Graph of molecular composition by mass
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Please leave us feedback.Why learn this
Every physical thing in the world is made up of matter. Whether it is the air we breathe, the food we eat, or the gas we use to heat our homes, almost everything that exists is made up of matter, and all matter is made up of molecules. Because of this, understanding the properties of molecules can help us better understand the concepts that explain the world around us, such as why different materials behave as they do. Molecular mass is also an important concept for anyone interested in pursuing a career in certain STEM fields.