Question

The empirical formula of butane, the fuel used in the disposal of
the empirical formula of butane, the fuel used in the disposal of lighters, is C₂H₅. In an experiment, the molar mass of butane was determined to be 58 g/mol. what is the molecular formula of butane

Answer 1

Answer on Question #44028 - Chemistry - Other

Question:

The empirical formula of butane, the fuel used in the disposal of lighters, is $C_2H_5$. In an experiment, the molar mass of butane was determined to be 58 g/mol. What is the molecular formula of butane?

Solution:

If the molecular formula of butane is $C_xH_y$ and the empirical formula is $C_2H_5$, then

$$x = 2 \cdot n \text{ and } y = 5 \cdot n,$$

i.e. the molecular formula may be written as $C_{2n}H_{5n}$

Molar mass of carbon – 12 g/mol, molar mass of hydrogen – 1 g/mol. Mass of the empirical formula is

$$M_{ef} = 12 \cdot 2 + 1 \cdot 5 = 29 \text{ g/mol}.$$

Since the molar mass of butane is 58 g/mol, than

$$n = M / M_{ef} = 58 / 29 = 2$$ $$x = 2 \cdot n = 2 \cdot 2 = 4,$$ $$y = 5 \cdot n = 5 \cdot 2 = 10,$$

So, the molecular formula of butane is $C_4H_{10}$.

Answer: $C_4H_{10}$

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