Determine the formula of a monohydric saturated alcohol, the molar mass of which is 74 g / mol.

Given:
M (alcohol) = 74 g / mol

To find:
alcohol formula -?

Decision:
1) Saturated monohydric alcohols have the general formula:
C (n) H (2n + 1) OH;
2) Using the periodic system of D.I.Mendeleev, calculate the molar mass of alcohol:
M (C (n) H (2n + 1) OH) = Mr (C (n) H (2n + 1) OH) = Ar (C) * n + Ar (H) * (2n + 1) + Ar ( O) + Ar (H) = 12 * n + 1 * (2n + 1) + 16 + 1 = (14n + 18) g / mol;
3) Make and solve the equation:
14n + 18 = 74;
14n = 56;
n = 4;
C4H9OH – butanol.

Answer: Unknown substance – C4H9OH – butanol.