Let $c_i$ is the specific heat capacity of a component $i$ in $[\pu{J K-1 kg-1}]$.

Let $w_i = \dfrac{m_i}{\sum_i{m_i}}$ is the mass fraction a component $i$.

Then the specific heat capacity of the mixture can be quite well approximated as if it were an ideal mixture.

$$c_\text{mix} = \sum_i{c_i \cdot x_i}$$

Deviations from ideality are complex and cannot be easily calculated without partial experimental data. The specific heat capacity of the mixture would have to be measured by calorimetry for various compositions and eventually interpolated for not measured ones.

Let $c_i$ is the specific heat capacity of a component $i$ in $[\pu{J K-1 kg-1}]$.

Let $w_i = \dfrac{m_i}{m}$ is the mass fraction a component $i$, while $m_i$ and $m$ are the mass of the component $i$ and the total mass of the mixture.

Then the specific heat capacity of the mixture can be quite well approximated as if it were an ideal mixture.

$$c_\text{mix} = \sum_i{c_i \cdot w_i}$$

Deviations from ideality are complex and cannot be easily calculated without partial experimental data. The specific heat capacity of the mixture would have to be measured by calorimetry for various compositions and eventually interpolated for not measured ones.

Let $c_i$ is the specific heat capacity of a component $i$ in $[\pu{J K-1 kg-1}]$.

Let $w_i = \dfrac{m_i}{\sum_i{m_i}}$ is the mass fraction a component $i$ in $[\pu{J K-1 kg-1}]$

Then the specific heat capacity of the mixture can be quite well approximated as

$$c_\text{mix} = \sum_i{c_i \cdot x_i}$$

Deviations from ideality are complex and cannot be easily calculated. The specific heat capacity of the mixture would have to be measured by calorimetry for various compositions and eventually interpolated for not measured ones.

Let $c_i$ is the specific heat capacity of a component $i$ in $[\pu{J K-1 kg-1}]$.

Let $w_i = \dfrac{m_i}{\sum_i{m_i}}$ is the mass fraction a component $i$.

Then the specific heat capacity of the mixture can be quite well approximated as if it were an ideal mixture.

$$c_\text{mix} = \sum_i{c_i \cdot x_i}$$

Deviations from ideality are complex and cannot be easily calculated without partial experimental data. The specific heat capacity of the mixture would have to be measured by calorimetry for various compositions and eventually interpolated for not measured ones.