Respuesta :
Answer: The true statements are [tex]\Delta H[/tex] for an endothermic reaction is positive, a combustion reaction is exothermic and when energy is transferred as heat from the system to the surroundings, [tex]\Delta H[/tex] is negative.
Explanation:
There are 2 types of chemical reactions categorized into heat change:
- Endothermic reactions: These reactions are defined as the reactions in which energy is absorbed by the system from the surroundings. The [tex]\Delta H[/tex] for these reactions is always positive. For Example: Changing of water into water vapor.
- Exothermic reactions: These reactions are defined as the reactions in which energy is released by the system to the surroundings. The [tex]\Delta H[/tex] for these reactions is always negative. For Example: Combustion reactions.
Combustion reactions are defined as the reactions in which a hydrocarbon reacts with oxygen gas to produce carbon dioxide and water. Heat is released during these reactions. Thus, it is considered as exothermic reactions.
Hence, the true statements are [tex]\Delta H[/tex] for an endothermic reaction is positive, a combustion reaction is exothermic and when energy is transferred as heat from the system to the surroundings, [tex]\Delta H[/tex] is negative.