# Gaseous State(Dalton's Law)

Why does the mixture of gases $\ce{NH3}$ & $\ce{HCl}$ not obey Dalton's Law of partial pressure at room temperature?
Also, what other mixtures don't obey Dalton's Law of partial pressure

• Your second question could make this post too broad. – M.A.R. Aug 30 '16 at 17:00
• Maybe because these gases react, forming solid ammonium chloride? See here: quora.com/… – AstronAUT Aug 30 '16 at 17:15
• Dalton's Law of partial pressures is not applicable to mixture of reacting gases. – narendra kumar Jan 2 '17 at 6:57

Where this assumption falls apart for your question is that $\ce{NH3}$ and $\ce{HCl}$ readily react with each other, both in the gas and aqueous phases. This alone renders Dalton's Law mute.
According to dalton's law " total pressure of a gas is sum of partial pressure of individual gases" but he clearly mentioned gases to be "non reacting". As $\ce{NH3 + HCl -> NH4Cl}$ So dalton's law not followed as they react. And also their pressure becomes zeo