How do you do gram to gram stoichiometry problems?

To solve gram to gram stoichiometry problems, follow these steps:

1. Write the Balanced Chemical Equation: Start by ensuring that the chemical equation for the reaction is balanced. This means that the number of atoms of each element is the same on both sides of the equation.
2. Convert Grams to Moles: Use the molar mass of the substance (found on the periodic table) to convert the mass you have (in grams) to moles. The formula is:

moles = grams / molar mass

3. Use Mole Ratios: From the balanced equation, identify the mole ratios between the reactant and the product of interest. This will tell you how many moles of one substance react with or produce another substance.
4. Convert Moles to Grams: If you need the final answer in grams, convert the moles of the desired product back to grams using its molar mass. The formula is:

grams = moles × molar mass

Example: If you have 10 grams of water (H₂O) and you want to determine how many grams of hydrogen gas (H₂) are produced from the reaction:

1. The balanced equation is 2H₂ + O₂ → 2H₂O.

2. Convert 10 grams of H₂O to moles:

10 g H₂O × (1 mol H₂O / 18 g H₂O) = 0.556 moles H₂O

3. Use the mole ratio (2 moles of H₂ produce 2 moles of H₂O), so:

0.556 moles H₂O × (2 moles H₂ / 2 moles H₂O) = 0.556 moles H₂

4. Convert moles of H₂ to grams:

0.556 moles H₂ × (2 g H₂ / 1 mol H₂) = 1.112 g H₂

This step-by-step method will help you confidently solve any gram to gram stoichiometry problem you encounter.