How can I convert weight percentage of calcium chloride hexahydrate to calcium chloride dihydrate? [closed]








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I have a chemical formula with $27\%$ $\ce{CaCl2.6H2O}$ and $43\%$ water with the balance of $30\%$ being other chemicals. 


I want to convert the $\ce{CaCl2.6H2O}$ and water percentage to $\ce{CaCl2.2H2O}$. I understand molecular weight percentage of $\ce{CaCl2}$ is higher in $\ce{CaCl2.2H2O}$ so I expect the percentage of calcium chloride will increase but I'm unable to calculate by how much.


Can you please show me how to calculate?




Do you understand that you're trying to do $\ce{CaCl2.6H2O -> CaCl2.2H2O + 4H2O}$? Just assume that in the beginning you had $\pu{100 gm}$ of the total mixture. So that makes the weight of $\ce{CaCl2.6H2O}$ present in the intial mixture to be:



> 
>  $27\%$ of $\pu{100 gm = 27gm}$.
> 
> 
> 


Next, calculate the number of moles of $\ce{CaCl2.6H2O}$ you had in the beginning by:



> 
>  dividing the mass you've just obtained by the molecular mass of this compound.
> 
> 
> 


Now according to the stoichiometry of the reaction I've given you, when $1$ mole of $\ce{CaCl2.6H2O}$ converts, you get $1$ mole of $\ce{CaCl2.2H2O}$. Can you calculate the mass of $\ce{CaCl2.2H2O}$ thus obtained? So now you've the mass of $\ce{CaCl2.6H2O}$ *and* $\ce{CaCl2.2H2O}$.


To calculate the percentage of $\ce{CaCl2}$ in $\ce{CaCl2.2H2O}$ all you've got to do is:



> 
>  $\displaystyle \frac{\text{Mass of } \ce{CaCl2}}{\text{Mass of } \ce{CaCl2.2H2O}} \times 100\%$
> 
> 
> 


You can carry out this step for $\ce{CaCl2.6H2O}$ on your own and then finally calculate the percentage change.


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