Chemical Reactions and Heat Energy Calculations

What type of reactions are described in the data provided? How do we calculate the amount of heat released in each reaction?

Answers:

3) The reaction is a combustion reaction. The heat released is 369.4 kJ/mol.

4) This is a synthesis reaction and the heat evolved is 65 kJ/mol.

5) The energy that is required is 40.25 kJ.

3) To calculate the heat released in the combustion reaction of ethanol, we first need to determine the number of moles of ethanol present. Given that 12.5g of ethanol is burned, we divide this by the molar mass of ethanol (46 g/mol) to find that it is equivalent to 0.27 moles. Since 1 mole of ethanol produces 1368 kJ of heat, by multiplying the number of moles by the heat produced per mole, we get 369.4 kJ/mol.

4) In the synthesis reaction of phosphorus with chlorine, we calculate the number of moles of phosphorus and chlorine based on their given masses. From these values, we determine the limiting reactant (chlorine) and use the stoichiometry of the reaction to find the heat released, which is 65 kJ/mol.

5) For the reaction between hydrosulfuric acid and oxygen gas, we again find the number of moles of each reactant. Identifying the limiting reactant (hydrogen sulfide), we then use the stoichiometry to calculate the heat released, which amounts to 40.25 kJ.

These calculations provide insights into the types of chemical reactions occurring and the corresponding heat energy changes that take place as a result.