Final answer:
The coefficient for C3H8 in the balanced chemical equation C3H8 + 5O2 → 3CO2 + 4H2O is 1.
Step-by-step explanation:
The coefficient that goes in front of the first compound C3H8 when the equation C3H8 + O2 → CO2 + H2O is fully balanced is 1. The balanced chemical equation is C3H8 + 5O2 → 3CO2 + 4H2O, indicating that 3 moles of carbon dioxide and 4 moles of water are produced from 1 mole of propane (C3H8) and 5 moles of oxygen gas. To balance the chemical equation, it is important to first balance the carbon (C) and hydrogen (H) atoms and then balance the oxygen (O) atoms using coefficients. Often, fractional coefficients may be necessary during the balancing process, but the final answer should be presented with whole number coefficients for all compounds.