In a three reactions system the first two reactions are endothermic with DeltaH values of 138kj and 241kj. if the final reaction is exothermic what is the minimum value of DeltaH3 that would make the overall reaction exothermic? explain your reasoning.

i beleive the minimum value of DeltaH3 would be -379 because if the final reaction is exothermic it would be releasing the heat absorbed?

In a three-reaction system, the overall reaction can be determined by the sum of the enthalpy changes (ΔH) of each individual reaction. If the first two reactions are endothermic, meaning they absorb heat from the surroundings, and the final reaction is exothermic, meaning it releases heat to the surroundings, we need to find the minimum value of ΔH3 that would make the overall reaction exothermic.

To determine this, we need to consider the overall enthalpy change (ΔH) of the system. If the overall reaction is exothermic, the sum of the enthalpy changes ΔH1, ΔH2, and ΔH3 should be negative.

ΔH overall = ΔH1 + ΔH2 + ΔH3

Let's assume the minimum value of ΔH3 that would make the overall reaction exothermic is X (negative value). Then, the equation becomes:

ΔH overall = ΔH1 + ΔH2 + X

Since ΔH1 = 138 kJ (endothermic) and ΔH2 = 241 kJ (endothermic), the equation can be rewritten as:

ΔH overall = 138 kJ + 241 kJ + X

To make the overall reaction exothermic, the sum of these values should be negative. Therefore:

138 kJ + 241 kJ + X < 0

Simplifying the equation:

379 kJ + X < 0

To find the minimum value of X that satisfies this inequality, we find that:

X < -379 kJ

Hence, the minimum value of ΔH3 that would make the overall reaction exothermic is -379 kJ.

Your reasoning is correct. If the final reaction is exothermic, it means it releases heat to the surroundings. To achieve an overall exothermic reaction, the heat released in the final reaction (ΔH3) needs to be sufficient to overcome the heat absorbed in the first two endothermic reactions (ΔH1 and ΔH2).

To determine the minimum value of ΔH3 that would make the overall reaction exothermic, we need to consider the principle of conservation of energy. The overall reaction will be exothermic if the total amount of energy released is greater than the total amount of energy absorbed.

In this case, we have two endothermic reactions with ΔH values of +138 kJ and +241 kJ. To make the overall reaction exothermic, we need the sum of these two values to be greater than zero.

So, to find the minimum value of ΔH3, we need to calculate the sum of the two endothermic reactions and set it equal to zero:

ΔH1 + ΔH2 + ΔH3 = 0

138 kJ + 241 kJ + ΔH3 = 0

379 kJ + ΔH3 = 0

ΔH3 = -379 kJ

Therefore, the minimum value of ΔH3 that would make the overall reaction exothermic is -379 kJ. This means that the third reaction must release at least 379 kJ of energy to compensate for the energy absorbed by the first two reactions.