Show events where Othello is described as impulsive in addition to being violent and destructive.

Impulsiveness is one of Othello's major flaws in the play, as well as the one that gets him in the most trouble. Despite his insistence for a fair trial in the accusation that he tricked Desdemona into marrying him, he makes up his mind about Cassio's dismissal and Desdemona's infidelity almost immediately.

Even when he claims to Iago that he still trusts Desdemona, he shows in an aside that he has begun to make up...

Impulsiveness is one of Othello's major flaws in the play, as well as the one that gets him in the most trouble. Despite his insistence for a fair trial in the accusation that he tricked Desdemona into marrying him, he makes up his mind about Cassio's dismissal and Desdemona's infidelity almost immediately.

Even when he claims to Iago that he still trusts Desdemona, he shows in an aside that he has begun to make up his mind about the truthfulness of Iago's statements before even seeing proof: 

"Why did I marry? This honest creature doubtless
Sees and knows more, much more, than he unfolds" (3.3.248-9)

Likewise, after Iago orchestrates Cassio's street brawl, Othello fires him from his lieutenant office without even hearing his side of the story:

"Cassio, I love thee
But never more be officer of mine.—" (2.3.211-2). 

Quick decisiveness is a necessary skill in battle, but it is not serving Othello in his interpersonal interactions. Othello's violence and comfort with destruction is another aspect of his character that would be immensely helpful in combat, but harms his personal life.  

This is absolutely evident when he believes that Desdemona has cheated on him. The moment he gives in to Iago's persuading, he cries, "Oh, blood, blood, blood!" (3.3.461), demanding that blood be shed for this injustice. 

Instead of confronting Desdemona directly about his suspicions, Othello reacts by verbally and physically abusing her, including slapping her in public in act 4, scene 1. This is an action that those around him are horrified by, as it suggests uncivilized behavior (as well as a loss of the deep love the couple was known for previously). When Othello finally kills Desdemona as a final solution to his problem, it's clear that violence is the only way he knows how to deal with emotions of this magnitude.