Because no chemical reaction takes place when amixtureis formed, no energy (e.g. heat, light or electrical energy) is released or absorbed during the formation of a mixture. Do mixtures consist of atoms or molecules? Mixturescan consist of either atoms or molecules - but must includeat least...
To be very clear, energy cannot flow from a less intense energy source to a more intense one, the flowing uphill of the first paragraph. This requires a reduction in entropy, which cannot happen in a Universe where every conversion of energy into work increases entropy, creating more disorder...