Consider the combustion reaction: C3H8 (g) + 5 O2(g) ---> 3 CO2(g) + 4H2O(g), where triangle symbol H= - 531 kcal/mol. If 6.70 x 10 to the 4th kcal of energy is released in the reaction,
How many grams of oxygen were consumed
22223
To find the number of grams of oxygen consumed in the combustion reaction, you can use the concept of stoichiometry. The stoichiometry relationship between C3H8 and O2 is 1:5, which means that for every 1 mole of C3H8, we need 5 moles of O2.
First, calculate the number of moles of C3H8 consumed using the given amount of energy released. The energy released is provided as 6.70 x 10^4 kcal. To convert this to kilojoules (kJ), multiply by 4.184 (since 1 kcal = 4.184 kJ).
Energy released = 6.70 x 10^4 kcal = 6.70 x 10^4 kcal × 4.184 kJ/kcal = 2.799 x 10^5 kJ
Next, use the energy released (ΔH) and the provided ΔH (ΔH = -531 kcal/mol) to find the number of moles of C3H8 consumed.
ΔH = -531 kcal/mol = -531 kcal/mol × 4.184 kJ/kcal = -2222 kJ/mol
Moles of C3H8 consumed = Energy released (kJ) / ΔH (kJ/mol)
Moles of C3H8 consumed = 2.799 x 10^5 kJ / -2222 kJ/mol ≈ -125.83 mol
Since the stoichiometric ratio for O2 to C3H8 is 5:1, multiply the number of moles of C3H8 consumed by 5 to get the moles of O2 consumed.
Moles of O2 consumed = -125.83 mol C3H8 × 5 = -629.15 mol O2
The result is negative because we are considering the consumption of reactants.
Finally, convert the moles of O2 consumed to grams of O2 using the molar mass of O2, which is approximately 32 g/mol.
Grams of O2 consumed = Moles of O2 consumed × Molar mass of O2
Grams of O2 consumed = -629.15 mol O2 × 32 g/mol ≈ -20133.28 g
Again, the result is negative because we are considering the consumption of reactants. However, we cannot have negative mass, so we take the absolute value of the result.
Absolute value of grams of O2 consumed = |-20133.28 g| = 20133.28 g
Therefore, approximately 20133.28 grams of oxygen were consumed in the combustion reaction.
To find the amount of oxygen consumed in the combustion reaction, we first need to calculate the number of moles of C3H8 consumed using the given energy released.
Step 1: Convert the energy released from kcal to joules:
Since 1 kilocalorie (kcal) is equal to 4.184 kilojoules (kJ), we can convert the energy released as follows:
Energy (J) = 6.70 x 10^4 kcal * 4.184 x 10^3 J/kcal
Step 2: Convert the energy to moles of C3H8:
Since the enthalpy change (triangle H) for the combustion of one mole of C3H8 is -531 kcal/mol, we need to calculate the number of moles of C3H8 that correspond to the given energy released:
moles of C3H8 = Energy (J) / (-531,000 J/mol)
Step 3: Determine the moles of O2:
From the balanced equation, we can see that for every 1 mole of C3H8, 5 moles of O2 are consumed. Therefore, the number of moles of O2 can be calculated as follows:
moles of O2 = moles of C3H8 * 5
Step 4: Convert moles of O2 to grams:
The molar mass of O2 is 32 g/mol, so we can convert moles of O2 to grams using this molar mass:
grams of O2 = moles of O2 * molar mass of O2
By following these steps, you can calculate the grams of oxygen consumed in the combustion reaction.