For the following reaction, 4.35 grams of hydrogen gas are allowed to react with with 10.3 grams of ethylene (C2H4).
hydrogen (g) + ethylene (C2H4) (g) ethane (C2H6) (g)
What is the maximum amount of ethane (C2H6) that can be formed? grams
What is the FORMULA for the limiting reagent?
What amount of the excess reagent remains after the reaction is complete? grams
© 2006 University of Massachusetts at Amherst
To determine the maximum amount of ethane (C2H6) that can be formed in the given reaction, we first need to determine which reactant is the limiting reagent. The limiting reagent is the reactant that is completely consumed in the reaction and determines the maximum amount of product that can be formed.
To find the limiting reagent, we need to compare the amount of product that can be formed from each reactant. We can use the concept of stoichiometry to do this.
1. Convert the mass of hydrogen gas (H2) to moles:
- Use the molar mass of H2 (2 g/mol) to convert from grams to moles.
- Divide the given mass (4.35 g) by the molar mass (2 g/mol) to find the number of moles of H2.
2. Convert the mass of ethylene (C2H4) to moles:
- Use the molar mass of C2H4 (28 g/mol) to convert from grams to moles.
- Divide the given mass (10.3 g) by the molar mass (28 g/mol) to find the number of moles of C2H4.
3. Write a balanced chemical equation:
hydrogen (g) + ethylene (C2H4) (g) -> ethane (C2H6) (g)
The balanced equation tells us the stoichiometric ratio between the reactants and products: 1:1 for H2 and C2H4 to form C2H6.
4. Compare the moles of each reactant:
- Divide the number of moles of H2 by the stoichiometric coefficient of H2 in the balanced equation.
- Divide the number of moles of C2H4 by the stoichiometric coefficient of C2H4 in the balanced equation.
The smaller result obtained from the two calculations will be the number of moles of the limiting reagent.
5. Convert the moles of the limiting reagent to grams of ethane:
- Multiply the number of moles of the limiting reagent by the molar mass of C2H6 (30 g/mol) to find the maximum amount of ethane in grams.
To find the formula for the limiting reagent, we compare the number of moles of each reactant to the stoichiometric coefficients in the balanced equation. Whichever reactant has the fewer moles compared to the stoichiometric coefficients is the limiting reagent.
To determine the amount of excess reagent remaining after the reaction is complete, we subtract the amount of the limiting reagent used from the initial amount of the excess reagent. We can use the stoichiometry of the balanced equation to calculate this.
By following these steps and performing the necessary calculations, you will be able to find the answers to the questions.