Let me help out the noobs here, think of apple cider as beer in one sense: most store bought cider has an O.G. of 1.050, so you can use a brewing calculation to approximate the pre freezing ABV%. Let's say, your ABV is 10%, so you know 10% of the quantity of cider you started with is pure alcohol, but you will play hell getting just the alcohol out if that is your only goal. A 1/2 gallon contains 64 oz, so maybe 6.4 oz is pure alcohol, right? I had good luck at 10* F in the freezer. There was a significant amount of water slush along with the what is now hooch. Drain off the first bit, and return rest to freezer. 3 or 4 hours later (or so) you can pour off a little more of the cider, and repeat until you are done for that session. DO NOT throw the ice out, as there is still alcohol in there, use your hydrometer to verify the residual alcohol after thawing, and freeze it out too.
You must diligent in controlling your fermentation temperatures, or you will have hot, nasty, boozy tasting applejack. And if the temperature do rise while fermenting your applejack will smell like acetone and also nasty.
Look, if your only goal is to see how much hooch is made when adding sugar to apple juice, have at it, but don't hurt yourself or anyone else by drinking too much.