Hacken vs. zerhacken
The German verbs hacken and zerhacken both relate to the act of chopping. The key difference lies in the intensity and the result of the action, with the prefix zer- in zerhacken indicating a more thorough, complete, or even destructive outcome.
Hacken
A2Hacken is the general, neutral term for "to chop" or "to hack". It describes the basic action of striking something with a sharp object like a knife, axe, or hoe. The focus is on the process itself, not necessarily on the final state of the object being chopped. It also has meanings in gardening ("to hoe") and technology ("to hack").
Ich muss noch die Zwiebeln für die Soße hacken.
(I still have to chop the onions for the sauce.)
Im Winter ging er oft in den Wald, um Holz zu hacken.
(In the winter, he often went into the forest to chop wood.)
Der Specht kann ein Loch in den Baumstamm hacken.
(The woodpecker can peck a hole in the tree trunk.)
Es ist illegal, die Computersysteme eines Unternehmens zu hacken.
(It is illegal to hack a company's computer systems.)
Die Gärtnerin muss das Unkraut im Beet hacken.
(The gardener has to hoe the weeds in the bed.)
Zerhacken
B1Zerhacken is an intensified version that means "to chop up completely", "to mince", or "to hack to pieces". The prefix zer- emphasizes the result: the object is thoroughly chopped into many small pieces. This can imply precision (like mincing) or destruction.
Für das Tatar muss man das Rindfleisch sehr fein zerhacken.
(For the steak tartare, you have to mince the beef very finely.)
Die Küchenmaschine kann Nüsse und Kräuter in Sekunden zerhacken.
(The food processor can chop up nuts and herbs in seconds.)
Aus Wut hat er den Brief in tausend Stücke zerhacken wollen.
(Out of anger, he wanted to chop the letter into a thousand pieces.)
Der Einbrecher hat die Holztür mit einer Axt zerhacken.
(The burglar hacked the wooden door to pieces with an axe.)
Die Filmkritiker haben seinen neuen Film regelrecht zerhacken.
(The film critics absolutely tore his new movie to pieces.)
Summary
In short, use hacken for the general act of chopping, like cutting vegetables or wood. Use zerhacken when you want to emphasize that something is being chopped completely into small pieces, either precisely (to mince) or destructively (to hack to bits). Think of hacken as "to chop" and zerhacken as "to chop up".