# What is the difference between standard chemical potential (μ standard) and the “pure” chemical potential (μ*)?

I am studying solutions for my thermodynamics course and I am a little confused about the chemical potential of a solute. I found the following from Atkins:

For a solute $\ce B$,obeying Henry's Law $p_\ce B=K_\ce B\, x_\ce B$, where $x_\ce B$ is the molar fraction

$$\mu =\mu^*+RT\ln\left(\frac{p}{p^*}\right)=μ^*+RT\ln\left(\frac{K}{p^*}\right)+RT\ln(x)$$

It then states:

$$\mu(\textrm{standard})=\mu^*+RT\ln\left(\frac{K}{p^*}\right)$$

Therefore, the chemical potential of B in an ideal-dilute sol. is:

$$\mu=\mu(\textrm{standard})+RT\ln(x)$$

The text often states that anything with the * means it is in its pure form, so $\mu^*$ would be chemical potential of $\ce B$ not mixed in with a solvent...but how does this physically differ from $\mu(\textrm{standard})\,?$