The effects of size on thermodynamic properties and the equilibrium constant were studied using nanosize zinc oxide and acetic acid solution as a research system. The experimental results indicate that the molar Gibbs free energy, the molar enthalpy and the molar entropy of the reaction decrease, but the equilibrium constant increases with decreasing reactant size. Linear trends were observed between the reciprocal of size for nano-reactant and thermodynamic variable, which are in good agreement with the previous reported results. (c) 2013 Elsevier Ltd. All rights reserved.