An ampere is not a substance that flows; it is a rate. One ampere is one coulomb per second. So a steady current held for a stated time delivers $Q = I\,t$ — read aloud, Q equals I t. $Q$ is the charge in coulombs, $I$ the current in amperes, $t$ the time in seconds. Seconds, always: the second buried inside the ampere needs something to cancel against, and only a time in seconds will do it.

That is the entire formula, and it is also the entire trap. Stopwatches read minutes, work orders read hours, and the formula reads seconds: $1\ \mathrm{min} = 60\ \mathrm{s}$ and $1\ \mathrm{h} = 3600\ \mathrm{s}$. Convert BEFORE the socket, never after — a conversion done late is a conversion done to the wrong number.

Two nuggets worth keeping. A coulomb is about $6.24 \times 10^{18}$ electrons, which is a ridiculous number to say and a very ordinary amount of electricity to use. And 96 500 coulombs is exactly one mole of them — which is why this small formula is the gate every plating calculation in the rest of this chapter has to walk through.