The chemical formula for calcium hydroxide is: Ca(OH)
Calculate the molar mass of calcium hydroxide. Round your answer to 2 decimal places. g\cdot mol
The Correct Answer and Explanation is:
74.09
Explanation:
To determine the molar mass of a chemical compound, the process involves summing the atomic masses of all the atoms present in its chemical formula. The result is expressed in grams per mole ( g/mol or g·mol⁻¹).
1. Analyze the Chemical Formula
The given chemical formula for calcium hydroxide is Ca(OH)₂. A breakdown of this formula reveals the number of atoms for each element:
- Ca (Calcium): There is one atom of calcium.
- O (Oxygen): The hydroxide group (OH) is in parentheses with a subscript of 2. This means the number of oxygen atoms is multiplied by two, resulting in two oxygen atoms.
- H (Hydrogen): Similarly, the subscript 2 applies to hydrogen, meaning there are two hydrogen atoms.
In summary, one formula unit of Ca(OH)₂ contains 1 calcium atom, 2 oxygen atoms, and 2 hydrogen atoms.
2. Find the Atomic Masses
The next step is to obtain the standard atomic mass for each element from the periodic table. For precision, it is best to use values with several decimal places.
- Atomic mass of Calcium (Ca) is approximately 40.078 g/mol .
- Atomic mass of Oxygen (O) is approximately 15.999 g/mol .
- Atomic mass of Hydrogen (H) is approximately 1.008 g/mol .
3. Calculate the Total Mass
Multiply the number of atoms of each element by its respective atomic mass and then sum the results.
- Mass from Calcium: 1 × 40.078 g/mol = 40.078 g/mol
- Mass from Oxygen: 2 × 15.999 g/mol = 31.998 g/mol
- Mass from Hydrogen: 2 × 1.008 g/mol = 2.016 g/mol
Adding these values together gives the total molar mass:
Molar Mass = 40.078 + 31.998 + 2.016 = 74.092 g/mol .
4. Round to the Correct Number of Decimal Places
The problem requires the final answer to be rounded to two decimal places.
Rounding 74.092 g/mol gives 74.09 g/mol .
