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PCAT Chemical Processes – Ionization Reactions

  • by Sam
  • Dec 18, 2017
  • PCAT Question of the Day

Consider the following ionization reactions:

H(g) –>  H+(g) + e-
F(g) –> F+(g) + e-

Which of the following statements is true?
A. H(g) releases energy and absorbs an electron
B. H(g) absorbs more energy than does fluorine and emits an electron
C. F(g) absorbs more energy than does hydrogen and emits an electron
D. F(g) releases energy and emits an electron

Click for Explanation

A. H(g) releases energy and absorbs an electron – Incorrect
B. H(g) absorbs more energy than does fluorine and emits an electron – Incorrect
C. F(g) absorbs more energy than does hydrogen and emits an electron – Correct
D. F(g) releases energy and emits an electron – Incorrect

Both reactions depict oxidation reactions in which the atoms are ionized and lose an electron. Thus (A) is correct as it asserts that an electron is absorbed. Ionizing an element is an endothermic process in which energy is absorbed, making (D) incorrect. Comparing choices B and C, we must determine which absorbs more energy. Since fluorine is a more electronegative element, it’s going to be harder to remove an electron. This will take more energy, making C the right answer.

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