Calculate The Molecular Weight Of Sodium Acetate, CH3C02Na. Sodium Acetate Is Sold As The Trihydrate Salt, Meaning It Contains 3 Water Molecules. Calculate The Molecular Weight Of The Trihydrate. CH3C02Na* 3H20.
The Correct Answer and Explanation is :
To calculate the molecular weight of sodium acetate trihydrate (CH₃CO₂Na·3H₂O), we need to account for the molecular weight of both the sodium acetate (CH₃CO₂Na) and the three water molecules (H₂O).
Step-by-step Calculation
- Molecular Weight of Sodium Acetate (CH₃CO₂Na):
- Carbon (C) has an atomic weight of approximately 12.01 g/mol.
- Hydrogen (H) has an atomic weight of approximately 1.008 g/mol.
- Oxygen (O) has an atomic weight of approximately 16.00 g/mol.
- Sodium (Na) has an atomic weight of approximately 22.99 g/mol.
Let’s break down the molecular weight of CH₃CO₂Na:
- CH₃ (methyl group) contains 1 carbon atom and 3 hydrogen atoms:
( 1 \times 12.01 + 3 \times 1.008 = 12.01 + 3.024 = 15.034 ) g/mol - CO₂ (carboxyl group) contains 1 carbon atom and 2 oxygen atoms:
( 1 \times 12.01 + 2 \times 16.00 = 12.01 + 32.00 = 44.01 ) g/mol - Sodium (Na) contributes:
( 1 \times 22.99 = 22.99 ) g/mol
Now, sum the atomic weights of CH₃CO₂Na:
( 15.034 + 44.01 + 22.99 = 82.034 ) g/mol.
So, the molecular weight of sodium acetate (CH₃CO₂Na) is approximately 82.03 g/mol.
- Molecular Weight of Water (H₂O):
Each water molecule (H₂O) consists of 2 hydrogen atoms and 1 oxygen atom:
- Hydrogen (H) contributes: ( 2 \times 1.008 = 2.016 ) g/mol
- Oxygen (O) contributes: ( 1 \times 16.00 = 16.00 ) g/mol
The molecular weight of one water molecule is:
( 2.016 + 16.00 = 18.016 ) g/mol.
- Molecular Weight of Sodium Acetate Trihydrate (CH₃CO₂Na·3H₂O):
Since there are 3 water molecules in the trihydrate form, we need to multiply the molecular weight of water by 3:
( 3 \times 18.016 = 54.048 ) g/mol.
Now, add the molecular weight of sodium acetate and the 3 water molecules:
( 82.03 + 54.048 = 136.078 ) g/mol.
Final Answer:
The molecular weight of sodium acetate trihydrate (CH₃CO₂Na·3H₂O) is approximately 136.08 g/mol.
Explanation:
The molecular weight of a compound is determined by summing the atomic weights of all the atoms present in its molecular formula. For sodium acetate trihydrate, we break down the formula into its components: sodium acetate (CH₃CO₂Na) and water (H₂O). After determining the individual molecular weights, we simply add them together to obtain the final result for the trihydrate. This compound contains three water molecules, which significantly contribute to its molecular weight.