Math Problem Statement

Consider the reaction C3H8 + 5O2 → 3CO2 + 4H2O. If 14.80 grams of C3H8, reacts with 3.44 g of O2. Determine the mass of CO2 that could be produced. a. Which reactant is the limiting reagent? b. How many grams of CO2 are formed? c. How much of the excess reactant remains after the reaction?

Solution

To solve this problem, we'll break it down into three parts, as requested: identifying the limiting reagent, calculating the mass of CO₂ formed, and determining how much of the excess reactant remains.

Step 1: Balanced Reaction

The balanced reaction is: C3H8+5O23CO2+4H2OC_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O This tells us that 1 mole of propane (C3H8)(C_3H_8) reacts with 5 moles of oxygen (O2)(O_2) to produce 3 moles of carbon dioxide (CO2)(CO_2) and 4 moles of water (H2O)(H_2O).

Step 2: Calculate Moles of Reactants

We need to find the moles of each reactant to determine which one is the limiting reagent.

  • Molar Mass of C3H8C_3H_8: C3H8=(3×12.01)+(8×1.008)=44.096g/molC_3H_8 = (3 \times 12.01) + (8 \times 1.008) = 44.096 \, \text{g/mol}
  • Molar Mass of O2O_2: O2=2×16.00=32.00g/molO_2 = 2 \times 16.00 = 32.00 \, \text{g/mol}

Now calculate the moles of each reactant:

  • Moles of C3H8C_3H_8: moles of C3H8=14.80g44.096g/mol=0.3355mol\text{moles of } C_3H_8 = \frac{14.80 \, \text{g}}{44.096 \, \text{g/mol}} = 0.3355 \, \text{mol}

  • Moles of O2O_2: moles of O2=3.44g32.00g/mol=0.1075mol\text{moles of } O_2 = \frac{3.44 \, \text{g}}{32.00 \, \text{g/mol}} = 0.1075 \, \text{mol}

Step 3: Identify the Limiting Reagent

From the balanced equation, we know that 1 mole of C3H8C_3H_8 reacts with 5 moles of O2O_2. Let's see how much O2O_2 is needed to react with 0.3355 moles of C3H8C_3H_8:

Required O2=0.3355mol×5=1.6775mol\text{Required } O_2 = 0.3355 \, \text{mol} \times 5 = 1.6775 \, \text{mol}

However, we only have 0.1075 moles of O2O_2, which is far less than the 1.6775 moles needed. This means that O2O_2 is the limiting reagent.

Step 4: Calculate the Mass of CO₂ Produced

Since O2O_2 is the limiting reagent, we will use the moles of O2O_2 to calculate the moles and then the mass of CO2CO_2 produced.

From the balanced equation, 5 moles of O2O_2 produce 3 moles of CO2CO_2. So, for 0.1075 moles of O2O_2, we get: Moles of CO2=35×0.1075=0.0645mol\text{Moles of } CO_2 = \frac{3}{5} \times 0.1075 = 0.0645 \, \text{mol}

Now, calculate the mass of CO2CO_2. The molar mass of CO2CO_2 is: CO2=12.01+(2×16.00)=44.01g/molCO_2 = 12.01 + (2 \times 16.00) = 44.01 \, \text{g/mol} Mass of CO2=0.0645mol×44.01g/mol=2.84g\text{Mass of } CO_2 = 0.0645 \, \text{mol} \times 44.01 \, \text{g/mol} = 2.84 \, \text{g}

Step 5: Calculate the Remaining Excess Reactant (Propane)

Now, let's determine how much C3H8C_3H_8 remains after the reaction. We know that 5 moles of O2O_2 react with 1 mole of C3H8C_3H_8, so 0.1075 moles of O2O_2 will react with: Moles of C3H8=15×0.1075=0.0215mol\text{Moles of } C_3H_8 = \frac{1}{5} \times 0.1075 = 0.0215 \, \text{mol}

Now, calculate the mass of C3H8C_3H_8 that reacted: Mass of C3H8 reacted=0.0215mol×44.096g/mol=0.948g\text{Mass of } C_3H_8 \text{ reacted} = 0.0215 \, \text{mol} \times 44.096 \, \text{g/mol} = 0.948 \, \text{g}

Initially, we had 14.80 g of C3H8C_3H_8. So, the mass of excess C3H8C_3H_8 remaining is: Mass of excess C3H8=14.80g0.948g=13.85g\text{Mass of excess } C_3H_8 = 14.80 \, \text{g} - 0.948 \, \text{g} = 13.85 \, \text{g}

Final Answers:

  1. Limiting reagent: O2O_2
  2. Grams of CO₂ formed: 2.84 g
  3. Excess reactant remaining: 13.85 g of C3H8C_3H_8

Would you like further details or explanations on any part of this process? Here are some related questions to explore:

  1. How do you calculate theoretical yield in chemical reactions?
  2. What are the differences between limiting reagents and excess reagents?
  3. How do you determine the molar mass of complex molecules?
  4. How does stoichiometry help in real-world chemical processes?
  5. Why is it important to identify the limiting reagent in a reaction?

Tip: Always make sure your units are consistent throughout calculations to avoid errors!

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Math Problem Analysis

Mathematical Concepts

Stoichiometry
Limiting Reagent
Molar Mass Calculations
Balanced Chemical Equations

Formulas

Moles = Mass / Molar Mass
Limiting Reagent: moles of O2 vs moles of C3H8
Mass of CO2 = Moles of CO2 × Molar Mass of CO2

Theorems

Law of Conservation of Mass
Stoichiometric Ratios

Suitable Grade Level

Grades 10-12