How do I determine the value of the reaction

2HI(g) + 2.4 kcal --> H2(g) + i2(g)
delta H =
a) 2.4 kcal
b) -2.4 kcal
c) 0.00024 kcal
d) -0.00024 kcal

To determine the value of the reaction, you need to calculate the change in enthalpy (delta H). In this case, the reaction is given as:

2HI(g) + 2.4 kcal --> H2(g) + I2(g)

The values on the left side of the reaction represent the reactants (2HI) and the value on the right side represents the products (H2 and I2). The coefficient in front of each molecule indicates how many of each are involved in the reaction.

Delta H represents the change in enthalpy, which is a measure of the heat energy exchanged during a chemical reaction. The delta H value can be positive if the reaction is endothermic (absorbs heat) or negative if the reaction is exothermic (releases heat).

To determine the value of delta H for this reaction, you need to compare the energy of the products to the energy of the reactants.

In the given reaction, the reactants are on the left side and have a total energy of 2.4 kcal. The products, H2 and I2, are on the right side.

Since the reaction does not specify any heat being added or subtracted, we can assume that the reaction is at constant pressure and that the 2.4 kcal represents the heat released by the reaction. Therefore, the reaction is exothermic, and the value of delta H is -2.4 kcal.

So, the correct answer is b) -2.4 kcal.