A compound contains 32% carbon, 4% hydrogen and rest oxygen ,its vapour density is 75. calculate the empirical and molecular formula.
Answers
Answer: The empirical formula is and molecular formula is .
Solution : Given,
If percentage are given then we are taking total mass is 100 grams.
So, the mass of each element is equal to the percentage given.
Mass of C = 32 g
Mass of H = 4 g
Mass of O = (100-36)= 64 g
Step 1 : convert given masses into moles.
Moles of C =
Moles of H = \frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{4g}{1g/mole}=4moles[/tex]
Moles of O =
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For C =
For H =
For O=
The ratio of C : H : O= 1 :1.5 :1.5
Converting them into simple whole number ratio by multiplying by 2.
Hence the empirical formula is
The empirical weight of = 2(12) + 3(1) +3(16)= 75g.
Molecular mass=
Now we have to calculate the molecular formula.
Molecular formula is