OK, I'm here to give something of a contrary view, but I hope its useful anyway.
I don't know how to make chemistry fun, because I already think its fun. I have since I was nine and had a chemistry set. I also like reading Shakespeare's plays, again, simply because I find them ... fun. So maybe I'm the last person to offer help.
However, the topics at hand in the OP, may not be the "funnest" ones around. There's some hard work ahead, the follows rules that aren't relateable to English grammar rules, and color changing indicators or production facility field trips won't add to the ability to learn the concepts at hand. They might help a high school kid with borderline ADD, but the concepts still have to be learned the hard way.
My sister is an educator for secondary school language. And she has a standard method that works for motivating students who simply don't want to learn. Kids from European and Latin American countries can be told, in similar words, "You are squandering the efforts your parents have sacrificed to advance your future, and that's disrespectful." Students will often (not always) immediately snap to attention, in response. "Being disrespectful" isn't a term that works on US students very well, but she can point out that their best effort is needed to insure they get the best grade on standardized tests and get into the best college programs. Again, she reminds them that a lax attitude to some classes is squandering their efforts to excel in their chosen field. Again, this only works sometimes, if the student is well aware of their future and their contributions to it.
I'm suggesting that maybe its worthwhile to present an adults eye view of the needs and requirements to the student, and see if maybe it works as a motivator.