In an analysis of an organic compound using Kjeldahl's method, the compound is found to contain 42 % nitrogen by mass. If 0.5 g of this compound is subjected to the procedure, the evolved ammonia completely neutralizes a certain volume of 0.5 M H ₂ SO ₄ solution. The volume of the acid consumed is _____ mL .

Step-by-step solution

According to Kjeldahl's method, the percentage of nitrogen is given by: % N = 1.4 N V w where N is the normality of the acid, V is the volume of the acid in mL , and w is the mass of the organic compound. Given: % N = 42 w = 0.5 g Molarity of H ₂ SO ₄ = 0.5 M The n-factor for H ₂ SO ₄ is 2 . Normality of H ₂ SO ₄ = 0.5 2 = 1.0 N Substituting the values into the formula: 42 = 1.4 1.0 V 0.5 V = 42 0.5 1.4 = 21 1.4 = 15 mL Answer: 15