Question

An organic compound whose empirical and molecular formla are same,contains 20%

Answer 1

Answer:

Urea , NH_2CONH_2

Explanation:

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= 20.0 g

Mass of H = 6.7 g

Mass of N = 46.7 g

Mass of O = 100- (20+6.7+46.7) = 26.6 g

Step 1 : convert given masses into moles.

Moles of C =$\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{20g}{12g/mole}=1.67moles$

Moles of H =$\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{6.7g}{1g/mole}=6.7moles$

Moles of N =$\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{46.7g}{14g/mole}=3.3moles[tex]</p><p></p><p>Moles of O =[tex]\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{26.6g}{16g/mole}=1.66moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{1.67}{1.66}=1$

For H = $\frac{6.7}{1.66}=4$

For N = $\frac{3.3}{1.66}=2$

For O =$\frac{1.66}{1.66}=1$

The ratio of C : H : N : O= 1 :4: 2: 1

Hence the empirical formula is CH_4N_2O

The empirical weight of CH_4N_2O = 1(12)+4(1)+2(14)+1(16)= 60 g

The molecular weight = 60 g/mole

NH_2CONH_2\rightarrow NH_3+HCNO

Urea gives biuret test used for detecting the presence of peptide bonds. Urea gives a violet colour with dilute solutions of Alkaline copper sulphate.