Consider the reaction between hydrogen and oxygen gases to form water: 2H2(g) + O2(g) �¨ 2H2O(l) Which of the following is not conserved in this reaction?

Possible answers

A.
atoms
B.
mass
C.
moles of molecules
D.
moles of atoms
E.
both moles of molecules and moles of atoms

To determine which factor is not conserved in the given reaction, we need to analyze the reaction equation. In this case, the equation is:

2H2(g) + O2(g) → 2H2O(l)

Let's break down the equation and identify the different elements and factors involved:

- Hydrogen (H2): We have 2 moles of hydrogen gas on the left side, and 4 moles on the right side, formulating 2 moles of water.
- Oxygen (O2): We have 1 mole of oxygen gas on the left side, and 2 moles on the right side, forming 2 moles of water.
- Water (H2O): We have no water on the left side and 2 moles of water on the right side.

By observing the equation, we can see that both hydrogen and oxygen are conserved in this reaction. The number of atoms of each element remains the same on both sides of the equation. Therefore, neither hydrogen nor oxygen is the correct answer.

However, there is a component that is not conserved in this reaction: states of matter. On the left side, both hydrogen (H2) and oxygen (O2) are in the gaseous state, while on the right side, water (H2O) is in the liquid state. The phase change from gas to liquid is not conserved in this reaction.

Therefore, the correct answer is the state of matter or the physical state of substances involved in the reaction.