steps for solving stoichiometry problems involving limiting reactants by solving for the limiting reaction first
a) Step 1: Write the balanced chemical equation.
b) Step 2: Calculate the molar mass of each reactant.
c) Step 3: Convert the mass of each reactant to moles.
d) Step 4: Use the stoichiometry of the balanced equation to find the moles of the product.
e) Step 5: Compare the moles of the product obtained from each reactant and identify the limiting reactant.
The Correct Answer and Explanation is:
To solve stoichiometry problems involving limiting reactants by solving for the limiting reactant first, the steps are as follows:
a) Step 1: Write the Balanced Chemical Equation.
Start by writing the balanced chemical equation for the reaction. This equation shows the relationship between the reactants and products. Each reactant and product must have correct stoichiometric coefficients that ensure the law of conservation of mass is followed.
For example, for the reaction:
[
\text{2H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}
]
b) Step 2: Calculate the Molar Mass of Each Reactant.
Next, calculate the molar mass of each reactant. The molar mass is the sum of the atomic masses of all atoms in a molecule or compound. You can find atomic masses on the periodic table. For example, the molar mass of H₂ is:
[
2 \times 1.008 \, \text{g/mol} = 2.016 \, \text{g/mol}
]
and the molar mass of O₂ is:
[
2 \times 16.00 \, \text{g/mol} = 32.00 \, \text{g/mol}
]
c) Step 3: Convert the Mass of Each Reactant to Moles.
Convert the mass of each reactant to moles using the formula:
[
\text{moles} = \frac{\text{mass}}{\text{molar mass}}
]
For example, if you have 10 grams of H₂, the number of moles of H₂ is:
[
\frac{10 \, \text{g}}{2.016 \, \text{g/mol}} = 4.96 \, \text{mol}
]
d) Step 4: Use the Stoichiometry of the Balanced Equation to Find the Moles of the Product.
Using the stoichiometric ratios from the balanced equation, calculate the moles of product produced by each reactant. For example, from the reaction:
[
\text{2H}_2 + \text{O}_2 \rightarrow 2\text{H}_2\text{O}
]
For 4.96 moles of H₂, you would use the ratio ( \frac{2 \, \text{mol H}_2\text{O}}{2 \, \text{mol H}_2} ) to calculate the moles of H₂O produced.
e) Step 5: Compare the Moles of the Product Obtained from Each Reactant and Identify the Limiting Reactant.
Once you’ve determined the moles of product from each reactant, compare them. The reactant that produces the smallest amount of product is the limiting reactant, as it is the one that will be entirely consumed first, limiting the amount of product that can be formed.
For example, if you have 4.96 moles of H₂ and 0.5 moles of O₂, you can use stoichiometry to determine how much H₂O each reactant would produce. If H₂ would produce 4.96 moles of H₂O, but O₂ would only produce 1 mole of H₂O, then O₂ is the limiting reactant.
By identifying the limiting reactant, you can then calculate the maximum possible amount of product that can be formed from the reaction.