The density of blood is $1\mathrm{.}06g.c{m}^{-3}.$

$2.$ Consider a closed system comprised of $3$ moles of air with an initial state of $\frac{4\mathrm{.}5}{b}ar$ and $0\mathrm{.}009m^3.$ After some unspecified process, the final state is $1\mathrm{.}5$ bar and $0\mathrm{.}027m^3.$ Assume air to be in its ideal$-$gas state and assume constant heat capacities $C_V^{ig}=20\mathrm{.}785$ and $C_P^{ig}=29\mathrm{.}100J.mo{l}^{-1}{?}^{-1}{K}^{-1}.$

Calculate the change in the molar internal energy of the ideal gas system. Support your results by developing an expression.