Reißen vs. zerreißen
The German words reißen and zerreißen both translate to tearing or ripping, but they describe different degrees of damage. The key difference lies in the prefix zer-, which in German usually indicates destruction or taking something completely apart.
Reißen
The verb reißen refers to the general action of tearing, ripping, or snapping. It is used when a material gets a tear, rips slightly, or snaps under physical tension, but the object itself usually remains in one piece rather than being completely destroyed.
Der Faden wird reißen, wenn du zu stark ziehst.
(The thread will snap if you pull too hard.)
Die Naht an meiner Hose ist gestern gerissen.
(The seam on my pants ripped yesterday.)
Das dünne Papier reißt sofort, wenn es nass wird.
(The thin paper tears immediately when it gets wet.)
Er hat beim Spielen ein großes Loch in sein Hemd gerissen.
(He tore a large hole in his shirt while playing.)
Die alte Gitarrensaite riss mitten im Konzert.
(The old guitar string snapped in the middle of the concert.)
Zerreißen
The verb zerreißen means to tear something into pieces, shred it, or rip it up completely. The prefix zer- signals total destruction, meaning the paper or fabric is purposefully or violently separated into multiple fragments and is no longer intact.
Sie zerriss das alte Foto in kleine Stücke.
(She tore the old photo into small pieces.)
Wir müssen diese geheimen Dokumente sofort zerreißen.
(We have to tear up these secret documents immediately.)
Der aggressive Hund hat das Kissen auf dem Sofa zerrissen.
(The aggressive dog shredded the pillow on the couch.)
Der wütende Autor hat sein eigenes Manuskript zerrissen.
(The angry author tore up his own manuscript.)
Ich werde diesen ungültigen Vertrag zerreißen.
(I will rip up this invalid contract.)
Summary
In short, you should use reißen when referring to a single tear, a rip, or a material snapping under pressure while mostly staying intact. On the other hand, you must use zerreißen when someone or something tears a material completely into pieces, resulting in its total destruction.