(a) Explain the concepts of fugacity and fugacity coefficient and where and how these are used in problem solving. (b) For a pure gas compound, its fugacity coefficient can be

calculated by the following equation: \ln \phi_{i}=\int_{0}^{P}\left(Z_{i}-1\right) \frac{d P}{P} \quad \text { Eq. } \mathbf{Q} 3 (1) Derive this equation through the concept of chemical potential. (ii) Calculate the fugacity of propane at 200°C and 10 MPa using Eq. Q3and the generalised compressibility Chart in Figure Q3.