Calculate the relative molecular mass of the following.
(i) Ethanol `(C_(2)H_(5)OH)`
(ii) Potassium permanganate `(KMnO_(4))`
(iii) Potassium dichromate `(K_(2)Cr_(2)O_(7))`
(iv) Sucrose `(C_(12)H_(22)O_(11))`

Explanation

(i) Ethanol `(C_(2)H_(5)OH)`
Molar mass = `(2 xx 12) + (6 xx 1) + (1 xx 16)`
= 24 + 6+ 16 = 46 g `mol^(-1)` .
(ii) Potassium permanganate `(KMnO_(4))`
Molar mass = 39 + 55 + `(4 xx 16)`
= 39 - 55 + 64 = 158 g `mol^(-1)` .
(iii) Potassium dichromate `(K_(2)Cr_(2)O_(7))`
Molar mass = `(39 xx 2) + (2 xx 52) + (7 xx 16)`
= 78+ 104+ 112 = 294 g `mol^(-1)` .
(iv) Sucrose `(C_(12)H_(22)O_(11))` Molar mass = `(12 xx 12) + (22 xx l) + (H xx 16)`
= 144 + 22 + 176 = 342 g `mol^(-1)`