Problem 2 - Chemistry An Atoms First Approach

Question

What is meant by the term lower in energy? Which is lower in energy, a mixture of hydrogen and oxygen gases or liquid water? How do you know? Which of the two is more stable? How do you know?

Step-by-Step Solution

Answer

The term "lower in energy" refers to a state with less potential energy, making it more stable. Liquid water is lower in energy when compared to a mixture of hydrogen and oxygen gases, as it releases energy in an exothermic reaction when formed. Consequently, liquid water is more stable than the hydrogen-oxygen gas mixture due to its lower potential energy.

Step 1: Understanding "Lower in Energy"

The term "lower in energy" refers to the state of a system with less or minimal potential energy. In chemical context, a lower energy state implies that the substance requires less energy to maintain its stability and therefore is more stable in comparison to others.

Step 2: Comparing Hydrogen-Oxygen Mixture and Liquid Water

In order to determine which is lower in energy in between a mixture of hydrogen and oxygen gases (H2 and O2) or liquid water (H2O), we need to consider the potential energy of both systems and their stability. When hydrogen and oxygen gases combine to form liquid water, it's an exothermic reaction. This means that energy is released during the reaction: \[ 2H_2 (g) + O_2 (g) \rightarrow 2H_2O (l) + energy\]

Step 3: Analyzing Stability

Since the formation of liquid water is exothermic, this means that the energy is released implying that liquid water has lower potential energy compared to the mixture of hydrogen and oxygen gases. States of matter with lower potential energy are generally more stable, as there is less stored energy that could be released unfavorably. As a result, liquid water is more stable than a mixture of hydrogen and oxygen gases as it has lower potential energy.

Step 4: Conclusion

In conclusion, "lower in energy" refers to minimal potential energy and hence higher stability. In this case, liquid water is lower in energy and more stable compared to a mixture of hydrogen and oxygen gases.