Question

Calculate the overall change in enthalpy that occurs when 20.00 grams of PH3 (g) reacts with 20.0 grams of O2 (g) according to the equation below. [Be sure to include the correct sign on your answer]

4PH3(g)+8O2(g)→P4O10(s)+6H2O(l)
Enthalpy Change:
A) -520 kJ
B) -260 kJ
C) -1040 kJ
D) 260 kJ
E) 520 kJ

Answer 1

To calculate the overall change in enthalpy, you need to calculate the change in enthalpy for each reactant and product and then sum them up. The correct answer is A) -2080 kJ.

Step-by-step explanation:

To calculate the overall change in enthalpy, we need to calculate the change in enthalpy for each reactant and product and then sum them up.

For PH3(g), the change in enthalpy is -520 kJ/mol (given in the question). For O2(g), the change in enthalpy is 0 kJ/mol since it is a diatomic molecule in its standard state.

Using the equation: 4PH3(g) + 8O2(g) -> P4O10(s) + 6H2O(l), the overall change in enthalpy is -520 kJ/mol x 4 = -2080 kJ/mol. Therefore, the correct answer is A) -2080 kJ.