[kelvinLTR]

find the number of degrees of freedom in a system formed by adding excess PbCl₂ to H₂SO₄ aqueous solution. Please explain how you got to the answer thanks in advance.

I'm struggling with finding the number of independent chemical components.

[Illuminatus]

Hi kelvinLTR,

1) If you write out the reaction, PbCl2(aq) +H2SO4(aq) -> PbSO4(s)+ 2HCL(aq), you can easily deduce the number of components in your system (don't worry about multiple constituents for ions, just don't forget to count water once). This is your C value.

2) Then, consider the fact that you have a precipitate form for one of the components when determining the number of phases in your system. This is your P value.

3) You no doubt already know the Gibbs' Phase Rule equation F=C-P+2, where F is the degrees of freedom; plug and chug.

Enjoy!