Ere are two parts to a chemical equation. The reactants are the elements or compounds on the left side of the arrow (-->). The elements and compounds to the right of the arrow are the products.
When we make food, our chemicals in our bodies, cleaning products etc
Answer : The standard enthalpy of formation of methane is, -74.8 kJ/mole
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation reaction of
will be,

The intermediate balanced chemical reaction will be,
(1)

(2)

(3)

Now we will reverse the reaction 1, multiply reaction 3 by 2 then adding all the equations, we get :
(1)

(2)

(3)

The expression for enthalpy of formation of
will be,



Therefore, the standard enthalpy of formation of methane is, -74.8 kJ/mole
Answer:
Reaction rate
Explanation:
We are told that Ben observes how quickly some dry wood is burning in a campfire.
This is an example of reaction rate because it tells us the speed i.e. how fast the dry wood is reacting with the camp fire.