The density of NaOH solution is 1.2 g cm$-$3. The molality of this solution is _____________ m. (Round off to the Nearest Integer)
[Use : Atomic mass : Na : 23.0 u, O : 16.0 u, H : 1.0 u, Density of H2O : 1.0 g cm$-$3]
Answer (integer)
5
Solution
Consider 1 litre solution<br><br>mass of solution = (1.2 $\times$ 1000)g = 1200 gm<br><br>Neglecting volume of NaOH<br><br>Mass of water = 1000 gm<br><br>$\Rightarrow$ Mass of NaOH = (1200 $-$ 1000)gm = 200 gm<br><br>$\Rightarrow$ Moles of NaOH = ${{200g} \over {50g/mol}} = 5$ mol<br><br>$\Rightarrow$ molality = ${{5mol} \over {1kg}} = 5$ m
About this question
Subject: Chemistry · Chapter: Some Basic Concepts of Chemistry · Topic: Mole Concept
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