I'm writing a (mock) college application essay for English. It's about what I learned from a bad experienced and the impact it had in the future. If the entire essay is supposed to be around 500 words, it is appropriate to have a paragraph describing the bad experience?

Absolutely. You need a brief description of the bad experience.

When writing a college application essay, it's important to make every word count and convey your message effectively within the given word limit. While it might be tempting to dedicate a full paragraph to describing the bad experience, it is advisable to use it as a brief introduction to set the context and provide the necessary background. Remember that the focus of the essay should be on the lessons learned and the subsequent impact on your future rather than dwelling too much on the negative experience itself. You can briefly summarize the bad experience in a concise manner and then transition smoothly into expressing the knowledge gained and its significance. This approach will allow you to allocate more space for discussing personal growth, reflection, and the positive outcomes resulting from overcoming the challenge.