Hess's law can be used to calculate reaction enthalpies for hypothetical processes that can't be carried out in the laboratory. set up a hess's law cycle that will let you calculate δ h∘ for the conversion of methane to ethylene: 2ch4(g) → c2h4(g)+2h2(g) you can use the following information: 2c2h6(g)ch4(g)c2h4(g)h2o(l),+++7o2( g)2o2(g)h2(g)→→→4co2(g)co2(g)c2h6(g ),++6h2o(l),2h2o(l),δh∘=−3120.8 kjδh∘=−890.3 kjδh∘=−136.3 kjδh∘f=−285.8 kj/mol
express your answer to four significant figures and include the appropriate units.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e

the correct answer is:

a. formation of precipitation

colorless gas, exhibiting a blue glow when placed in an electric field

b) solid

its a type of rock