Gadolinium doped ceria (GDC) which is used as an electrolyte in solid oxide fuel cells, shows significant expansion when exposed to low partial pressures of oxygen. Such a chemical expansion has been attributed to the creation of charge compensating vacancies and the change in the oxidation state of cerium. The chemically induced mechanical stresses also affect diffusion characteristics. Two material properties govern this interaction between stresses and diffusion in ionic solids. These are the chemical coefficient of expansion and the change in elastic properties like Young's modulus with composition. The aim of this research is to determine and study these properties using Molecular Dynamics (MD) simulation for 10 and 20GDC using existing interatomic potential parameters. Results show that chemical expansion is purely volumetric with negligible or no change in MD simulation cell shape. Further it was concluded that there is a linear relation between chemical strains and non-stoichiometry in GDC for the studied range of non-stoichiometry. There was also a drastic reduction in the Young's modulus for higher vacancy concentrations in 10 and 20GDC.