According to NASA, the space shuttle's external fuel tank for the main propulsion system carries 7246 kg of liquid O2 and 283.2 kg of liquid H2. During takeoff, these chemicals react to form water as well as giving out a great amount of energy. ____ O2(g) + ____ H2(g) → ______ H2OHow many kg of the excess reactant is left over?

For determining the amount of limiting reactant or excess reactant, the mole ratio of reactants in a balanced reaction must be known. Moles of particular compound can be calculated by dividing its mass by its molar mass. Molar mass of a particular compound can be calculated by adding the molar mass of the elements present in the formula of the compound.Mass of O2=7246 kg=7246×1000=7.246×106 g Mass of H2=283.2 kg=283.2×1000=2.832×105 gThe balanced reaction is as follows: O2g + 2H2g → 2H2Og Molar mass of O2 = 32 g/mol Molar mass of H2 = 2 g/mol Moles of H2 and O2 are calculated as follows: Moles of O2=Mass of O2Molar mass of O2=7.246×10632=2.264×105 mol Moles of H2=Mass of H2Molar mass of H2=2.832×1052=1.416×105 mol According to the given reaction, 2 moles of H2 react with 1 mole of O2. Thus, 1.416×105 moles of H2 react with=12×1.416×105=7.080×104 moles of O2 Hence, excess moles of O2 =Available moles of O2 - Reacted moles of O2=2.264×105 - 7.080×104=1.556×105 mol Mass of excess reactant is calculated as follows: Mass of excess O2=Excess moles of O2 × Molar mass of O2=1.556×105×32=4.979×106 g =4.979×1061000=4979 kgAnswer: 4979 kg of the excess reactant is left over.