Question

Is hydrocyanic acid (HCN) more soluble in water or in carbon disulfide (CS2)? Why?

Answer 1

To answer this question you must remember the rule "like dissolves like" this helps to remember how a solvent works basically what it says is that a polar substance will dissolve a polar substance a non polar substance will dissolve a non polar substance

A polar substance will not dissolve a non polar substance so this is about polarity, lets find it

H C N , this is all about putting together the electronegativity values H has aelectronegativy value of 2.1, has a value of 2.5 and N has a value of 3 so the Carbon has a higher force than hydrogen to attract electrons and Nitrogen has a higher value than carbon so if we draw it we get:

------------------>------------------->, there is a force to attract electrons, this is called a dipole moment so because of the existance of it this molecule is considered to be polar

If you repeat this procedure for water and CS₂ you will find that water is a polar molecule

CS₂ is a nonpolar molecule  

So according to the rule HCN is more soluble in water than CS₂

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