In "To Kill a Mockingbird" if Tom is found guilty on appeal, what will his punishment be? Why?
If Tom's appeal fails, then he'll be executed. More specifically, he'll be sent to the electric chair. Rape was a capital crime in Alabama at that time, and the maximum sentence was death. But the rape of a white woman by a black man was considered even more serious, one that always needed to be punished by the ultimate sanction. To most white people, it wasn't just a criminal act but a full-frontal attack on the foundations of society. The prevailing racial prejudice held that African-American males were little better than savages, and were always on the look out for white women to have sex with. Even if such sex was consensual it was still considered dangerous, because white women could then give birth to mixed-race children and that constituted a threat to prevailing notions of white supremacy. So it was widely believed that white women needed to be protected from predatory black males. One way of doing this was through lynching. Another way was the death penalty, which was effectively a legalized form of lynching.
In chapter 23, Scout, as always, given her curious nature, is asking Atticus all sorts of questions about the trial. She asks him at one point what will happen if Tom loses his appeal, and is found guilty. Atticus replies, "He'll go to the chair...unless the Governor commutes his sentence." The reason that Tom will be sentenced to death ("the chair" means he will be killed by the electric chair, after a death sentence is given to him) is that "rape's a capital offense in Alabama." That means that rape is one of the most serious crimes that you can commit, according to Alabama law, and therefore is subject to the death penalty. So, Tom's only chance, his only hope, is to be proven innocent of the crime, and to have the crime dismissed. If he is found guilty on appeal, he will be sentenced to death. It's a rather grave situation. I hope that helped!