what mass of excess reactant remians when the reaction is completed?
To determine the mass of excess reactant remaining when a reaction is completed, you need the following information:
1. Balanced chemical equation: Make sure you have a balanced chemical equation for the reaction.
2. Reactant stoichiometry: Determine the molar ratio of reactants from the balanced equation. This ratio tells you the proportion in which the reactants combine.
3. Initial masses: Know the initial masses of the reactants involved in the reaction.
4. Limiting reactant: Identify the limiting reactant, which is the one that is completely consumed and limits the amount of product formed. This can be determined by comparing the actual molar amounts of each reactant with the stoichiometric ratio.
Once you have the above information, follow these steps:
1. Calculate the molar amount of each reactant: Divide the mass of each reactant by its molar mass to obtain the corresponding number of moles.
2. Determine the limiting reactant: Compare the molar amounts of the reactants calculated in step 1 with the stoichiometric ratio from the balanced equation. The reactant with the smaller resulting amount is the limiting reactant.
3. Calculate the theoretical yield: Use the stoichiometric ratio from the balanced equation to convert the moles of the limiting reactant to moles of the product formed.
4. Calculate the excess reactant mass remaining: Subtract the theoretical amount (in moles) of the excess reactant from the initial amount (in moles) of the excess reactant, and then multiply the resulting moles by the molar mass of the excess reactant to obtain the mass remaining.
Remember, the excess reactant is the one that is not completely consumed in the reaction and is present in excess.