What Is The Molar Mass Of Calcium Nitrate, Ca(NO3)2, Rounded To The Nearest Whole Number?
A 102 G/Mol
B 328 G/Mol
C 164 G/Mol
D 150 G/Mol
The correct answer and explanation is :
To calculate the molar mass of calcium nitrate (Ca(NO₃)₂), we need to determine the atomic masses of all the elements in the compound and then sum them according to their quantities in the formula.
Step 1: Break Down the Formula
The chemical formula of calcium nitrate is Ca(NO₃)₂. This indicates that the compound consists of:
- 1 calcium (Ca) atom
- 2 nitrate (NO₃) groups, where each nitrate contains:
- 1 nitrogen (N) atom
- 3 oxygen (O) atoms
Step 2: Determine Atomic Masses
The atomic masses (rounded to the nearest whole number) are:
- Calcium (Ca): 40 g/mol
- Nitrogen (N): 14 g/mol
- Oxygen (O): 16 g/mol
Step 3: Calculate the Molar Mass of Each Component
- Calcium (Ca):
The molar mass of calcium is 40 g/mol, and there is 1 Ca atom in the formula.
Contribution of calcium = ( 1 \times 40 = 40 \, \text{g/mol} ). - Nitrate (NO₃) Groups:
Each nitrate group consists of:
- 1 nitrogen atom: ( 1 \times 14 = 14 \, \text{g/mol} )
- 3 oxygen atoms: ( 3 \times 16 = 48 \, \text{g/mol} ) So, the molar mass of one nitrate group (NO₃) is:
[ 14 + 48 = 62 \, \text{g/mol} ] Since there are 2 nitrate groups (NO₃) in calcium nitrate, the total molar mass contribution from the nitrate groups is:
[ 2 \times 62 = 124 \, \text{g/mol} ]
Step 4: Sum the Molar Masses
Now, we add the contributions from calcium and the two nitrate groups:
[
\text{Total molar mass} = 40 \, \text{g/mol (Ca)} + 124 \, \text{g/mol (NO₃)} = 164 \, \text{g/mol}
]
Final Answer:
The molar mass of calcium nitrate (Ca(NO₃)₂) is 164 g/mol.
Thus, the correct answer is C 164 G/Mol.