Question
How can I find the molecular weight of a hydrocarbon?
Answers
GPT-4o mini
To find the molecular weight (molar mass) of a hydrocarbon, you can follow these steps:
1. **Determine the Chemical Formula**: Identify the chemical formula of the hydrocarbon. Hydrocarbons consist of carbon (C) and hydrogen (H) atoms, typically represented as \( C_nH_m \), where \( n \) and \( m \) are the numbers of carbon and hydrogen atoms, respectively.
2. **Find Atomic Weights**: Use the periodic table to find the atomic weights of carbon and hydrogen:
- Carbon (C) has an atomic weight of approximately 12.01 g/mol.
- Hydrogen (H) has an atomic weight of approximately 1.008 g/mol.
3. **Calculate the Molecular Weight**:
- Multiply the number of carbon atoms (C) by the atomic weight of carbon.
- Multiply the number of hydrogen atoms (H) by the atomic weight of hydrogen.
- Add these values together.
The formula for calculating the molecular weight is:
\[
\text{Molecular Weight} = (n \times \text{Atomic Weight of C}) + (m \times \text{Atomic Weight of H})
\]
For example, for \( C_4H_{10} \) (butane):
- Number of C atoms = 4
- Number of H atoms = 10
Calculation:
\[
\text{Molecular Weight} = (4 \times 12.01 \, \text{g/mol}) + (10 \times 1.008 \, \text{g/mol}) \\
= (48.04 \, \text{g/mol}) + (10.08 \, \text{g/mol}) \\
= 58.12 \, \text{g/mol}
\]
So, the molecular weight of butane (\( C_4H_{10} \)) is about 58.12 g/mol.
Repeat these steps for any hydrocarbon by adjusting the \( n \) and \( m \) values according to its chemical formula.
1. **Determine the Chemical Formula**: Identify the chemical formula of the hydrocarbon. Hydrocarbons consist of carbon (C) and hydrogen (H) atoms, typically represented as \( C_nH_m \), where \( n \) and \( m \) are the numbers of carbon and hydrogen atoms, respectively.
2. **Find Atomic Weights**: Use the periodic table to find the atomic weights of carbon and hydrogen:
- Carbon (C) has an atomic weight of approximately 12.01 g/mol.
- Hydrogen (H) has an atomic weight of approximately 1.008 g/mol.
3. **Calculate the Molecular Weight**:
- Multiply the number of carbon atoms (C) by the atomic weight of carbon.
- Multiply the number of hydrogen atoms (H) by the atomic weight of hydrogen.
- Add these values together.
The formula for calculating the molecular weight is:
\[
\text{Molecular Weight} = (n \times \text{Atomic Weight of C}) + (m \times \text{Atomic Weight of H})
\]
For example, for \( C_4H_{10} \) (butane):
- Number of C atoms = 4
- Number of H atoms = 10
Calculation:
\[
\text{Molecular Weight} = (4 \times 12.01 \, \text{g/mol}) + (10 \times 1.008 \, \text{g/mol}) \\
= (48.04 \, \text{g/mol}) + (10.08 \, \text{g/mol}) \\
= 58.12 \, \text{g/mol}
\]
So, the molecular weight of butane (\( C_4H_{10} \)) is about 58.12 g/mol.
Repeat these steps for any hydrocarbon by adjusting the \( n \) and \( m \) values according to its chemical formula.