Hess’s law is very powerful. It allows us to combine equations to generate new chemical reactions whose enthalpy changes can be calculated, rather than directly measured. Besides that, Hess’s law states that when chemical equations are combined algebraically, their enthalpies can be combined in exactly the same way. Below points are to be taken as well: 1) If a chemical reaction is reversed, the sign on ΔH is changed; 2) If a multiple of a chemical reaction is taken, the same multiple of the ΔH is taken as well. As attached is an example of Hess Law problem solving question. By using Hess law , combine the equation algebraically and determine the enthaphy change of the reaction.

The answer to the question: choose the correct statement.  a) when ethane reacts with fluorine gas the product is less stable.b) addition reactions of unsaturated hydrocarbons and halogens requires a high activation energy.  c)the double covalent bond within unsaturated hydrocarbons requires a lot of energy to break.  d)the double covalent bond within unsaturated hydrocarbons can be broken easily.is: a) when ethane reacts with fluorine gas the product is less stable.

1. why does the same side of the moon always face earthc.the rotational period of the moon is equal to one revolution around earth2. which is greater the moons period of rotation or its period of revolution  b.the moons revolution period around earth3.what was the major accomplishment of the apollo missions  d.landing on and exploring the moon4. which of these space missions involved the deployment of lunar rovers d.apollo5. which scientists are going to explore next on kepler-186fd. evidence of existence of life6.which mission is not going to explore the outside of the solar systemb.safir7.which technology limit the future of space exploration b. scientist must first develop certain technologies before missions can be completed.