Being stuck is normal and is not a sign of anything. Being stuck for forty minutes without changing what you are doing is the part worth fixing.
First, work out which kind of stuck you are
graph TD A["Stuck"] --> B{"Can you say what quantity is wanted, and in what units?"} B -->|no| C["Re-read it aloud. Underline the quantity and its unit"] B -->|yes| D{"Do you have a balanced equation, if the question needs one?"} D -->|no| E["Write it and balance it before anything else"] D -->|yes| F{"Do you know a worked example like this?"} F -->|no| G["Open the concept page. Find the nearest case"] F -->|yes| H{"Where exactly does yours differ?"} H -->|one step| I["Do that step alone, on its own"] H -->|everywhere| J["Ask — you are missing an idea, not a step"]
The bottom-right branch matters most. If your problem differs from the worked example everywhere, no amount of staring will close the gap, because what you are missing is a concept rather than a step. That is the moment to ask, not an hour later.
Units are a debugging tool, not decoration
This is the single most useful habit in the course and almost nobody arrives with it.
Write every quantity with its unit, then write the unit you are trying to end up with. Now check whether the operation you are about to perform produces that unit.
- Grams divided by grams per mole gives moles. Correct.
- Grams multiplied by grams per mole gives grams squared per mole, which is not a thing. You divided when you should have multiplied, or the other way round, and the units caught it before the arithmetic did.
- Moles per litre times litres gives moles. Correct.
- Moles per litre divided by litres gives moles per litre squared, which is your signal to stop.
Most “I don’t know which formula to use” is really “I have not written the units down”. If you carry them through every line, a substantial fraction of wrong answers refuse to be written.
Then ask: is this number a plausible size?
The second habit. Before you accept an answer, ask whether it could be true.
- A few grams of anything is a small fraction of a mole, not four hundred moles.
- A percentage yield of 3% or of 900% is telling you something went wrong in the arithmetic, unless you can say exactly why.
- A concentration of 40 mol/L is denser than most things dissolve.
- A gas volume of 0.002 L from a spatula of solid is too small; a volume of 2000 L is too large for a bench.
You do not need to know the right answer to know that an answer is absurd, and noticing takes five seconds. This is also, quietly, how professionals catch their own mistakes.
Things to try before asking, in order of how often they work
- Say the question out loud. A surprising share of stuck is misreading, and your ear catches what your eye skipped.
- Write down what you know, with units, and what you want, with its unit.
- Write the balanced equation and mark on it which quantity you were given and which you want. Half of the stoichiometry problems in this course solve themselves at that point, because the route becomes visible.
- Do the simpler version. One mole instead of 0.0374. A 1:1 ratio instead of 2:3. Then look at what the awkward version changed.
- Find the sentence where your understanding stops. Not the page — the sentence. That sentence is your question.
Then ask well
“I don’t get it” gets you a re-explanation of something you may already understand. Any of these gets you a real answer in one exchange:
| Instead of | Say |
|---|---|
| ”I don’t get the mole" | "I can get from grams to moles, but I don’t know why the ratio from the equation goes in there" |
| "The lab didn’t work" | "We calculated 1.42 g of precipitate and recovered 1.31 g, and I can’t tell if that gap is losses or an error" |
| "I’m lost on titrations" | "I follow it up to the endpoint, then I lose which concentration I’m solving for" |
| "My answer’s wrong" | "I get 0.0421 and the back of the page says 0.0842, which is exactly double” |
Each of those tells me where to start. The first column tells me nothing, so my first three questions have to be diagnostic — and that is three minutes you did not need to spend. The last row is the best kind of question, because “exactly double” is a clue that points at one specific thing.
Twenty minutes, then ask
That is the rule I would like you to use on homework. Twenty minutes of genuine attempts, with the attempts written down, and then stop and bring them to me. The written attempts are not evidence against you; they are the most useful thing you can hand me, because a wrong attempt shows exactly which idea is bent.
Where to ask: Getting Help has the routes and Help Sessions has the times. If the problem is that your result disagrees with everyone else’s, that is a different and more interesting situation — see Mistakes Are Data.