Use the standard reduction potentials to determine what is
observed at the cathode during the electrolysis of a 1.0 M
solution of KBr that contains phenolphthalein. What
observation(s) is(are) made?
O2(g) + 4 H+(aq) + 4 e– :rarrow: 2 H2O(l) E° = 1.23 V
Br2(l) + 2e– :rarrow: 2 Br–(aq) E° = 1.07 V
2 H2O(l) + 2 e– :rarrow: H2(g) + 2 OH– E° = –0.80 V
K+(aq) + e– :rarrow: K(s) E° = –2.92 V
(A) Solid metal forms.
(B) Bubbles form and a pink color appears.
(C) Dark red Br2(aq) forms.
(D) Bubbles form and the solution remains colorless.
The answer is (B). So I know that H2 gas and OH- are formed at the cathode, so that's where the pink color comes from. But what exactly forms at the anode? Is it Br2 gas? Why wouldn't it be Br2 liquid?
observed at the cathode during the electrolysis of a 1.0 M
solution of KBr that contains phenolphthalein. What
observation(s) is(are) made?
O2(g) + 4 H+(aq) + 4 e– :rarrow: 2 H2O(l) E° = 1.23 V
Br2(l) + 2e– :rarrow: 2 Br–(aq) E° = 1.07 V
2 H2O(l) + 2 e– :rarrow: H2(g) + 2 OH– E° = –0.80 V
K+(aq) + e– :rarrow: K(s) E° = –2.92 V
(A) Solid metal forms.
(B) Bubbles form and a pink color appears.
(C) Dark red Br2(aq) forms.
(D) Bubbles form and the solution remains colorless.
The answer is (B). So I know that H2 gas and OH- are formed at the cathode, so that's where the pink color comes from. But what exactly forms at the anode? Is it Br2 gas? Why wouldn't it be Br2 liquid?