Chemical Energetics

$CH_4 + 2O_2 \rightarrow CO_2 + 2H_2O$

$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$

$HCl + NaOH \rightarrow NaCl + H_2O$

$2H_2 + O_2 \rightarrow 2H_2O$

The reaction is exothermic because the products are at a lower energy level than the reactants.

The reaction is endothermic because the products are at a lower energy level than the reactants.

The reaction is exothermic because the products are at a higher energy level than the reactants.

The reaction is endothermic because the products are at a higher energy level than the reactants.

Condensing steam into liquid water

The combustion of hydrogen gas

Separating a molecule of chlorine into individual atoms

The formation of sodium chloride from its ions

Bond breaking and bond forming are both exothermic processes.

Bond breaking and bond forming are both endothermic processes.

Bond breaking is exothermic, while bond forming is endothermic.

Bond breaking is endothermic, while bond forming is exothermic.

$kJ \cdot mol^{-1}$

$J \cdot g^{-1}$

$kJ \cdot mol$

$^{\circ}C \cdot mol^{-1}$

The combustion of methane gas in a burner.

The reaction between sodium hydroxide and hydrochloric acid.

The process of photosynthesis in green plants.

The respiration process in living cells.

$+550\ kJ/mol$

$-550\ kJ/mol$

$+5350\ kJ/mol$

$-5350\ kJ/mol$

Arrow X

Arrow Y

Both Arrow X and Arrow Y

Neither Arrow X nor Arrow Y

The energy released during bond making is greater than the energy required for bond breaking.

The energy required for bond breaking is equal to the energy released during bond making.

The energy required for bond breaking is greater than the energy released during bond making.

No bonds are broken during the reaction.