JAMB - Chemistry (1984 - No. 4)
A molar solution of caustic soda is prepared by dissolving
40 g NaOH in 100 g of water
40 g NaOH in 1000 g of water
20 g NaOH in 500 of solution
20 g NaOH in 1000 g of solution
2o g NaOH in 80 g of solution
Explanation
A molar solution implies concentration in terms of moles/liter. The respective atomic weights for NaOH are: Na - 23,0 - 16 and H - 1, so the molecular weight, is 23 + 16 + I = 40. Thus 40 grams of NaOH equals one mole of NaOH, and a 1 molar solution of NaOH will contain 40 grams of NaOH chemical in 1000grams of water.
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