Answer to Question #90899 in General Chemistry for acadia carlson

Question

Lactic acid, the substance that causes sour milk to taste as it does, has a formula weight of 74. It consists of 48.63% C and 8.18% H, with the rest being oxygen. Calculate the empirical and molecular formulas of lactic acid, arranging the atomic symbols in alphabetical order.

Answer 1

Since C= 48.63 %, thus no. of carbon atoms can be calculated as 48.63/12= 4.05

Similarly, for H = 8.18/1 = 8.18

For Oxygen (100-48.63-8.18)/16 = 2.69

Thus, the formula becomes C_4.05H_8.18O_2.69

Thus, dividing each entity by 2.69 The formula becomes: C_1.5H_3.0O_{1 (}Empirical Formula)

Multiplying above formula by 2 to get whole number ratio gives: C₃H₆O₂ (molecular formula)