Answer :
To find the heat absorbed when bromine reacts with hydrogen, we calculate the energy required to break the bonds in the reactants and the energy released in forming the products, then adjust for the given amounts of reactants to find the proportionate heat absorbed.
To calculate the heat absorbed when 38.2 g of bromine reacts with 12.4g of hydrogen, we apply the principles of thermochemistry. First, we need to ensure that the reaction is balanced and then use the given enthalpy changes and molar masses to find the total heat absorbed or released.
The reaction provided is: H2(g) + Br2(g)
arr 2HBr (g). We are told that breaking one mole of H2 bonds requires 436 kJ and breaking one mole of Br2 bonds requires 193 kJ. Formation of two moles of H-Br bonds releases 732 kJ. Since the reaction forms two moles of HBr, the total energy release from bond formation is 2
arr 732 kJ = 1464 kJ. The total energy required for breaking the bonds is 436 kJ + 193 kJ = 629 kJ.
Therefore, the net energy released as heat when bromine reacts with hydrogen is 1464 kJ - 629 kJ = 835 kJ. To find the heat absorbed based on the masses given, we must then convert the mass of reactants to moles, determine the limiting reactant, and calculate the proportionate amount of heat absorbed.
