Question

What is the empirical formula and molecular formula for lactic acid if the percent composition is 40.00% C, 6.71% H, 53.29% O, and the approximate molar mass is 90 g/mol?

Answer 1

Answer on Question#49174 – Chemistry – Other

What is the empirical formula and molecular formula for lactic acid if the percent composition is 40.00% C, 6.71% H, 53.29% O, and the approximate molar mass is 90 g/mol?

Solution:

$$W(C) = 40.00\%; \ W(H) = 6.71\%; \ W(O) = 53.29\%;$$ $$v(C): v(H): v(O) = \frac{W(C)}{M(C)} : \frac{W(H)}{M(H)} : \frac{W(O)}{M(O)} = 3.33 : 6.71 : 3.33 = 1 : 2 : 1;$$

CH₂O (the empirical formula);

$$M(CH_2O) = 30 \ \text{g/mol}; \ M(C_xH_yO_2) = 90 \ \text{g/mol};$$

C₃H₆O₃ (the molecular formula);

Answer: CH₂O (the empirical formula); C₃H₆O₃ (the molecular formula).

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