When is it reactants minus products

Post by Tiffany Ju » Tue Jan 13, am. Laurence Lavelle Skip to content. Quick links. Email Link. Tsang 3 1 1 silver badge 3 3 bronze badges. Add a comment. Active Oldest Votes. Improve this answer. Josh Mitchell Josh Mitchell 7 7 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. Featured on Meta. Now live: A fully responsive profile. Note: that the element phosphorus is a unique case.

The reference form in phosphorus is not the most stable form, red phosphorus, but the less stable form, white phosphorus. The enthalpy of formation of carbon dioxide at Write the chemical equation for the formation of CO 2. This equation must be written for one mole of CO 2 g.

In this case, the reference forms of the constituent elements are O 2 g and graphite for carbon. Because O 2 g and C graphite are in their most elementally stable forms, they each have a standard enthalpy of formation equal to Kirchhoff's Law describes the enthalpy of a reaction's variation with temperature changes. In general, enthalpy of any substance increases with temperature, which means both the products and the reactants' enthalpies increase.

The overall enthalpy of the reaction will change if the increase in the enthalpy of products and reactants is different. At constant pressure, the heat capacity is equal to change in enthalpy divided by the change in temperature.