By and large, lab reports are subject to the whims of your professor in any given topic. There are many different formats and requirements. Schedule a meeting with your professor to discuss her/his thoughts and requirements. If you are unable to do that, find another student who has taken the course from that professor and ask them what works and what doesn't.
In general, the APA Style Reporrt (6th edition) can be a good format for creating a lab report. This is a Word document style you can download. In Word, click on "New" and then type "APA" in the search field. The style should appear as a choice. Download it and use it to start your report. The style contains paragraphs that explain the kinds of information that should go in each section. As a bonus, the style makes it very easy to do citations and references.
As for references on something like the problem you posed:
The problem is really very basic and doesn't lend itself to finding germane information. But, in general, if you use a search engine like Google or DuckDuckGo and you type "Journal" followed by something from your problem, you will often find scholarly articles that say something about the topic. For example, the problem you posted was (in part) about a halide test. Typing in, "Journal Halide test for anion" I found 8 articles. Scan the articles and find something interesting you can bring up in your paper, then cite it. Sometimes it may be nothing more than a textbook explanation that's better than the one in your text book. On something as basic as the topic you raised, I would expect the professor to ask only for references to your assigned text book. That's not uncommon.
With these tools in hand, search for journal articles in chemistry. Scan them - don't try to understand them. You're looking for style and form. Learn how a scholarly article is written by the kinds of content the author(s) provide.
In the end, the professor may only want you to copy the information in your lab assignment and then provide a paragraph of conclusions. That's not uncommon either. Again, ask him/her what she/he expects.
I hope that helps.