AP Chemistry Question of the Day--22

Welcome back to my blog. Here comes the answer to question 21 I posted yesterday. The correct answer is C. 

Can be considered the addition of one process of x and two processes of y. 

Hess's Law states that if a chemical change takes place by several different routes, the overall enthalpy change is the same, regardless of the route by which the chemical change occurs (provided the initial and final condition are the same). Addition of chemical equations leads to a net or overall equation. If enthalpy change is known for each equation, the result will be the enthalpy change for the net equation.

Can be considered the addition of one process of x and two processes of y. As a result, the enthalpy change should be equal to x+2y. C is the right answer.

 Following is Question 22 of the series. 

22. N2 molecules absorb ultraviolet light but not visible light. I2 molecules absorb both visible and ultraviolet light. Which of the following statements explains the observations?

(A) More energy is required to make N2 molecules vibrate than is required to make I2 molecules vibrate.
(B) More energy is required to remove an electron from an I2 molecule than is required to remove an electron from a N2 molecule.
(C) Visible light does not produce transitions between electronic energy levels in the N2 molecule but does produce transitions in the I2 molecule.
(D) The molecular mass of I2 is greater than the molecular mass of N2.

I will post the answer and explanation tomorrow. 

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