Chemistry, 26.06.2019 05:00 shawn451

Consider the chemical equations shown here. which equation shows how to calculate hrxn for the equation below? what is hrxn for the overall reaction?

Consider the chemical equations shown here. which equation shows how to calculate hrxn for the equat

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Answer from: kutsarver

The enthalpy change of the reaction comes out to be -890 kJ

Explanation:

To calculate the enthalpy of the reaction divided in multiple steps, we use Hess's law. This law states that the heat absorbed or evolved in a given chemical equation remains same whether the process occurs in one step or several steps.

To apply this law, the enthalpy of the chemical equation is treated as ordinary algebraic expression and it can be added or subtracted to form the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes that occur during intermediate reactions.

For the given overall reaction:

$CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(l)$

The two intermediate reactions are as follows:

Reaction 1: $CH_4(g)+2O_2(g)\rightarrow CO_2(g)+2H_2O(g);\Delta H_1=-802kJ$

Reaction 2: $H_2O(g)\rightarrow 2H_2O(l);\Delta H_2=-88kJ$

By adding both the reactions, we will get the overall enthalpy of the reaction, which is:

$\Delta H_{rxn}=\Delta H_1+\Delta H_2\\\\\Delta H_{rxn}=[(-802)+(-88)]kJ=-890kJ$

Hence, the enthalpy change of the reaction comes out to be -890 kJ

Answer from: Quest

n has four pairs of electrons in the valence shell, electrons repel one another ,n has 7 protons in its nucleus, and since n has 7 protons, it must fill the second shell, giving it 4 pairs of electrons. the electrons form 3 bonds and 1 lone pair of electrons. each pair of electrons repels the other pairs, so they are equally far apart.

so all of the above

Answer from: Quest

adding or remove a gaseous reactant or product changes the concentrations. if the concentration of reactant or product is increased, the system will shift away from the side in which concentration was increased (i.e. if the concentration of reactants is increased, the system will shift toward the products. if more products are added, the system will shift to form more reactants). conversely, if the concentration of reactant or product is decreased, the system will shift toward the side in which concentration was decreased (i.e. if reactants are removed, the system will shift to form more reactants. if the concentration of products is decreased, the equilibrium will shift toward the products).

explanation:

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