To determine the enthalpy change of the unknown reaction using Hess's Law and the given data, follow these steps:1. Identify the two known reactions and their enthalpy changes. Let's call these reactions A and B, with enthalpy changes H_A and H_B, respectively.2. Write down the unknown reaction that the student wants to find the enthalpy change for. Let's call this reaction C, with an enthalpy change of H_C.3. Analyze reactions A and B to see if they can be combined or manipulated in any way to produce reaction C. This may involve reversing one or both of the known reactions, or multiplying them by a constant to balance the stoichiometry of the unknown reaction.4. If necessary, reverse one or both of the known reactions. Remember that reversing a reaction changes the sign of its enthalpy change. For example, if you reverse reaction A, its new enthalpy change will be -H_A.5. If necessary, multiply one or both of the known reactions by a constant to balance the stoichiometry of the unknown reaction. Remember that multiplying a reaction by a constant also multiplies its enthalpy change by the same constant. For example, if you multiply reaction A by 2, its new enthalpy change will be 2H_A.6. Combine the manipulated known reactions to form the unknown reaction. Add the enthalpy changes of the manipulated reactions to find the enthalpy change of the unknown reaction. For example, if you reversed reaction A and multiplied reaction B by 2, the enthalpy change of the unknown reaction would be H_C = -H_A + 2H_B.7. Perform the experiment by carrying out the manipulated known reactions in a calorimeter, and measure the temperature change for each reaction. Use the temperature change, the specific heat capacity of the substances involved, and the mass of the substances to calculate the enthalpy changes of the manipulated reactions.8. Use the calculated enthalpy changes of the manipulated reactions and the equation from step 6 to find the enthalpy change of the unknown reaction.By following these steps, the student can determine the enthalpy change of the unknown reaction using Hess's Law and the given data.