1.
C6H12O6 + 6O2 --> 6CO2 + 6H2O ∆H = -2803 kJ
Correct Answer
A. Exothermic
Explanation
The given chemical equation represents the process of cellular respiration, where glucose (C6H12O6) is oxidized to produce carbon dioxide (CO2) and water (H2O) with the release of energy. The negative value of ΔH (-2803 kJ) indicates that the reaction releases energy to the surroundings, making it exothermic.
2.
6CO2 + 6H2O --> C6H12O6 + 6O2 ∆H = +2803 kJ
Correct Answer
B. Endothermic
Explanation
The given chemical equation represents the process of photosynthesis, where carbon dioxide and water are converted into glucose and oxygen with the help of sunlight. The positive value of ΔH (+2803 kJ) indicates that energy is absorbed or taken in during this reaction. Since an endothermic reaction is characterized by the absorption of heat or energy from the surroundings, the given reaction is endothermic.
3.
3NO2 + H2O --> 2HNO3 + NO ∆H = - 138 kJ
Correct Answer
A. Exothermic
Explanation
The given reaction is exothermic because it releases heat energy. This is indicated by the negative value of ΔH, which is -138 kJ. In an exothermic reaction, the products have lower energy than the reactants, and the excess energy is released as heat.
4.
C + H2O --> CO + H2 ∆H = + 113 kJ
Correct Answer
A. Exothermic
Explanation
The given chemical reaction releases heat energy, as indicated by the positive value of ∆H (113 kJ). This means that the reaction is exothermic. In an exothermic reaction, the products have lower energy than the reactants, and the excess energy is released as heat.
5.
CH4 + 2 O2 --> CO2 + 2 H20 + 213.2 KJ
Correct Answer
A. Exothermic
Explanation
The given chemical reaction is exothermic because it releases energy in the form of heat. This is indicated by the positive value of 213.2 KJ, which represents the heat released during the reaction. In an exothermic reaction, the products have lower energy than the reactants, resulting in the release of energy.
6.
N2(g) + O2(g) + 43 kcal -----> 2 NO(g)
Correct Answer
B. Endothermic
Explanation
The given reaction is endothermic because it requires energy in the form of heat to proceed. This is indicated by the positive value of 43 kcal, which represents the heat absorbed during the reaction. In an endothermic reaction, the reactants have lower energy than the products, and energy is absorbed from the surroundings to make up the difference.
7.
Correct Answer
B. Endothermic
8.
C3H8(g) + 5 O2(g) -----> 3 CO2(g) + 4H2O(g) + 2200 kJ
Correct Answer
A. Exothermic
Explanation
The given chemical equation represents the combustion of propane (C3H8) in the presence of oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). The release of 2200 kJ of energy indicates that this reaction is exothermic. In an exothermic reaction, energy is released in the form of heat, making the surroundings warmer.
9.
Correct Answer
A. Exothermic
10.
If a reaction finishes with more energy than it started, it must be a
Correct Answer
A. Exothermic
Explanation
If a reaction finishes with more energy than it started, it must be an exothermic reaction. In an exothermic reaction, energy is released to the surroundings, resulting in a decrease in the overall energy of the system. This means that the final energy of the reaction products is lower than the initial energy of the reactants. Therefore, if the reaction finishes with more energy than it started, it indicates that energy has been released, making it an exothermic reaction.