Chapter 3
Q. 3.7
The molar mass of acetic acid, as determined with a mass spectrometer, is about 60 g/mol. Using that information along with the simplest formula found in Example 3.6, determine the molecular formula of acetic acid.
ANALAYSIS | |
simplest formula (CH_{2}O) MM_{a}: actual molar mass (60 g/mol) |
Information given: |
molecular formula | Asked for: |
STRATEGY
1. Determine the molar mass of the simplest formula, MM_{s}
2. Find the ratio
\frac{\text{ actual molar mass}}{\text{simplest formula molar mass}} = \frac{MM_{a}}{MM_{s}}
3. To get the molecular formula, multiply all subscripts in the simplest formula by the ratio.
Step-by-Step
Verified Solution
12.01 g C + 2(1.008) g H + 16.00 g O = 30.03 g CH_{2}O/mol | 1. MM_{s} |
\frac{MM_{a}}{MM_{s}} = \frac{60}{30.03} = 2 | 2. ratio |
C_{1×2}H_{2×2}O_{1×2} The molecular formula of acetic acid is C_{2}H_{4}O_{2}. | 3. molecular formula |