If 9 g of H2O decomposes, how many moles of hydrogen gas are produced?

To determine how many moles of hydrogen gas are produced when 9 g of water (H2O) decomposes, we start by understanding the chemical reaction involved. The decomposition of water can be represented by the equation:

2 H2O → 2 H2 + O2

This equation indicates that for every 2 moles of water that decompose, 2 moles of hydrogen gas are produced, meaning the molar ratio of H2O to H2 is 1:1.

First, we need to convert the mass of water into moles. The molar mass of water (H2O) can be calculated as follows:

• Hydrogen (H): Approximately 1 g/mol, and there are two hydrogen atoms, contributing 2 g/mol.
• Oxygen (O): Approximately 16 g/mol.

Thus, the molar mass of water is:

2 g/mol (from H) + 16 g/mol (from O) = 18 g/mol.

Next, we can convert the mass of water used (9 g) into moles:

Moles of water = mass / molar mass = 9 g / 18 g/mol = 0.5 moles.

According to the stoichi