a certain organic compound contains only carbon ,hydrogen and oxygen .A 4.24g sample of the compound burnt ,and gives 8.45g of carbon 4 oxide and 3.46g of water. If it has a molecular mass of 88,determine its molecular formula
First, we need to calculate the mass of hydrogen and oxygen present in the sample.
Mass of carbon = 8.45 g
Mass of oxygen in CO2 = 2 * 8.45 g = 16.9 g
Mass of water = 3.46 g
Mass of hydrogen in H2O = 2 * 3.46 g = 6.92 g
Total mass of carbon, hydrogen, and oxygen = 16.9 g + 6.92 g = 23.82 g
Mass of the remaining component (i.e., carbon, hydrogen, and oxygen not accounted for in CO2 and H2O) = 4.24 g - 23.82 g = -19.58 g
This negative mass indicates that there was an error in the experiment or calculation.
Assuming the mass is positive, we can calculate the number of moles of each component:
Moles of carbon = 8.45 g / 12.01 g/mol = 0.703 mol
Moles of oxygen = 16.9 g / 16.00 g/mol = 1.06 mol
Moles of hydrogen = 6.92 g / 1.01 g/mol = 6.86 mol
The simplest whole-number ratio of moles is 1:9:4, which gives the empirical formula CH4O.
To find the molecular formula, we need to know the molecular mass. The empirical formula has a mass of 32 (12 for carbon, 4 for hydrogen, and 16 for oxygen).
The ratio of the molecular mass to the empirical formula mass is 88 / 32 = 2.75.
We can multiply the subscripts in the empirical formula by 2.75 to get the molecular formula:
C2H11O2
Therefore, the molecular formula of the organic compound is C2H11O2.