yes

could someone tell me why the alchimist became evil

People have been corrupt with the use of Ember, also known as the Ember Blight. The Alchemist has fallen under this corruption and hasn't been cured of it. He hopes to destroy all Ember hoping that it will cure him of the affliction.

Using the Heart of Ordrak doesn't help.

引用自 Headhunter99：

could someone tell me why the alchimist became evil

First of All: People really need to put Up Spoiler Warnings!

Second: There is a Sidequest in the first Act related to him where you have to find his notes in a cave which explain everything. Pretty interesting story because it shows...

!SPOILER!

...that it was his intention to do so even before TL I started.

i never played the first game when i did that sidequest i kept being attacked befor i could finish it

Yes, and it makes me really sad

引用自 Justforvisit：

引用自 Headhunter99：

could someone tell me why the alchimist became evil

First of All: People really need to put Up Spoiler Warnings!

Second: There is a Sidequest in the first Act related to him where you have to find his notes in a cave which explain everything. Pretty interesting story because it shows...

!SPOILER!

...that it was his intention to do so even before TL I started.

I was under the impression that he made those notes after the events of TL1, because that's when he got afflicted with the ember blight, just like the other playable characters. He either didn't get it fully cured when the others did, or he contracted it again seeking more power/ember after Ordrak was already dead.

I think after he kills Ordrak he says he wants to keep exploring (or experimenting) with Ember, so I'd agree with Cannonaire that he got reinfected.

引用自 HiFive：

I think after he kills Ordrak he says he wants to keep exploring (or experimenting) with Ember, so I'd agree with Cannonaire that he got reinfected.

The Alchemist written ending of TL1 pairs well with the TL2 quest to recover his notes.

Finally got this picture. It seems he became obsessed with trying to make dark ember and must have been reinfected.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3559832896

Meanwhile, the wizard in town was staying safely put and just asking for people to bring him different types of ember to test.

引用自 HiFive：

Meanwhile, the wizard in town was staying safely put and just asking for people to bring him different types of ember to test.

Somebody has to stay behind and maintain the market in every Rpg.

Another description of what happened to the Alchemist.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3592334905

引用自 HiFive：

Another description of what happened to the Alchemist.
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3592334905

Although little additional context is given in the first 2 games; have to wonder if part of this decision at the time was also to protect The Alchemist's reputation or standing. Perhaps the beyond-the-hill consequences of this would be Vale and The Destroyer helping other imperials and allies to avoid the same mistake in the future. This would be the 2nd time something like this happened if counting Alric from TL1.