Výpočet procenta krystalové vody
Kolik procenta krystalové vody obsahuje:
dodekahydrát fosforečnanu sodného
\( \mathrm{f}\left(\mathrm{Na}_{3} \mathrm{PO}_{4} \cdot 12 \mathrm{H}_{2} \mathrm{O}\right)=\frac{12 \cdot M_{(2)}\left(H_{2} \mathrm{O}\right)}{M_{r}\left(Na_{3} P \mathrm{H}_{4} \mathrm{O}\right)}=\frac{216}{379,97}=0,5685 \Rightarrow \mathbf{56,85} \% \mathbf{H}_{\mathbf{2}} \mathbf{O} \)
\( \mathrm{f}\left(\mathrm{Na}_{3} \mathrm{PO}_{4} \cdot 12 \mathrm{H}_{2} \mathrm{O}\right)=\frac{12 \cdot M_{(2)}\left(H_{2} \mathrm{O}\right)}{M_{r}\left(Na_{3} P \mathrm{H}_{4} \mathrm{O}\right)}=\frac{216}{379,97}=0,6585 \Rightarrow \mathbf{65,85} \% \mathbf{H}_{\mathbf{2}} \mathbf{O} \)
\( \mathrm{f}\left(\mathrm{Na}_{3} \mathrm{PO}_{4} \cdot 12 \mathrm{H}_{2} \mathrm{O}\right)=\frac{12 \cdot M_{(2)}\left(H_{2} \mathrm{O}\right)}{M_{r}\left(Na_{3} P \mathrm{H}_{4} \mathrm{O}\right)}=\frac{216}{379,97}=0,5185 \Rightarrow \mathbf{51,85} \% \mathbf{H}_{\mathbf{2}} \mathbf{O} \)
\( \mathrm{f}\left(\mathrm{Na}_{3} \mathrm{PO}_{4} \cdot 12 \mathrm{H}_{2} \mathrm{O}\right)=\frac{12 \cdot M_{(2)}\left(H_{2} \mathrm{O}\right)}{M_{r}\left(Na_{3} P \mathrm{H}_{4} \mathrm{O}\right)}=\frac{216}{379,97}=0,4685 \Rightarrow \mathbf{46,85} \% \mathbf{H}_{\mathbf{2}} \mathbf{O} \)