Welcome back to my blog. Here comes the answer to question 19 I posted yesterday. The correct answer is B.
If the ΔH is negative, the process is releasing heat. We call it exothermic. Process v is a sublimation process, where solid absorbs heat to become gas. Process w is a ionization process, where one electron is removed from a potassium atom. Since there is static attraction between the electron and the nucleus, energy needs to be absorbed to remove the electron. Process x is a chemical bond breaking process. To break chemical bonds, energy needs to be absorbed too. Process y is a process where chlorine atom gains one electron and become isoelectronic with argon. The chloride ion gained extra stability because the outmost shell becomes full. As a result, energy is released. Process z is a process of ionic bond formation process. Bond formation processes are always exothermic. So, processes y and z are exothermic and answer B is the right answer.
Following is Question 20 of the series. It is in continuation of Question 17, 18 and 19.
20 . The elements K and Cl react directly to form the compound KCl according to the equation below.
It is observed that the reaction producing KCl from its elements goes essentially to completion. Which of the following is a true statement about the thermodynamic favorability of the reaction?
(A) The reaction is favorable and driven by an enthalpy change only.
(B) The reaction is unfavorable and driven by an entropy change only.
(C) The reaction is favorable and driven by both enthalpy and entropy changes.
(D) The reaction is unfavorable due to both enthalpy and entropy changes.
I will post the answer and explanation tomorrow.
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