Why does Jack hate voting for chief? How does he react to the vote? How does Ralph react?

Jack Merridew wants power. This is evident the minute we meet him. He isn't physically imposing but his manner is authoritarian and one who "knows his mind." The boys decide voting for a chief might be a good way to organize themselves. Democracy becomes a toy for them but they are actually mimicking their old world. Jack wants power and the voting process is uncertain. When all the boys outside his choir vote for Ralph, Jack is mortified. His anger boils over to violence but Ralph is able to quickly appease him. Ralph seems to follow some sort of instinct which tells him that Jack would work much better as a friend than a foe. So, Ralph gives Jack the choir and calms him down , at least for a while.