Learn Hardcore German: Der Wasserkocher schaltet sich automatisch aus, sobald das Wasser kocht. - The electric kettle switches off automatically as soon as the water boils.

Gender is lexical: you generally have to learn the gender with each noun.
Many device / tool nouns ending in -er are masculine:
- der Computer, der Toaster, der Drucker, der Mixer
  This pattern helps, but it’s not an absolute rule.
In this sentence, der Wasserkocher is also the subject, so the article is in the nominative case. That’s why it’s der, not den (accusative) or dem (dative).

What does sich do in schaltet sich automatisch aus? Why is it there?

sich is a reflexive pronoun (3rd person singular). Here it means “itself”:

Der Wasserkocher schaltet sich aus.
= The kettle switches itself off.

The verb behaves like this:

jemanden / etwas ausschalten = to switch someone/something off
- Ich schalte den Wasserkocher aus. – I switch the kettle off.
sich ausschalten = to switch oneself / itself off
- Der Wasserkocher schaltet sich aus. – The kettle switches itself off.

Grammatically, sich here is:

accusative (direct object),
referring back to der Wasserkocher (same person/thing as the subject).

Why is it schaltet sich automatisch aus and not ausschaltet sich automatisch?

Because ausschalten is a separable-prefix verb.

In a main clause with a conjugated verb:

The finite verb goes in second position.
The separable prefix goes to the end of the clause.

So:

Infinitive: ausschalten
Main clause (present, 3rd person):
- Er schaltet das Licht aus.
- Der Wasserkocher schaltet sich automatisch aus.

Putting it as ausschaltet sich automatisch would be like saying in English: “switchesoff itself automatically” – you’re not separating the prefix, which is ungrammatical in a normal main clause.

Could you leave out sich and just say Der Wasserkocher schaltet automatisch aus?

Native speakers would find Der Wasserkocher schaltet automatisch aus odd or incomplete.

Reasons:

ausschalten is normally transitive: it wants an object:
- Ich schalte den Wasserkocher aus.
If der Wasserkocher is the thing being switched off and there is no external agent (no “I/you”), German usually uses the reflexive form:
- Der Wasserkocher schaltet sich automatisch aus.

Alternatives that do work:

Der Wasserkocher geht automatisch aus.
(here the verb is ausgehen, which is intransitive: something can simply “go off”.)
Der Wasserkocher schaltet sich automatisch ab.
(same reflexive pattern, but abschalten instead of ausschalten.)

So in this structure, keeping sich is the natural way to say it.

Why does aus come at the end in schaltet sich automatisch aus?

Because aus is the separable prefix of ausschalten.

Rule for separable-prefix verbs in a main clause:

The conjugated part goes in position 2.
The prefix goes to the end of the clause.

Examples:

Ich schalte das Licht aus.
Der Computer fährt von allein herunter. (from herunterfahren)
Der Wasserkocher schaltet sich automatisch aus.

In contrast, in infinitives or subordinate clauses, the verb is not split:

… ohne den Wasserkocher auszuschalten.
…, weil sich der Wasserkocher automatisch ausschaltet.

Why is automatisch in the middle: schaltet sich automatisch aus? Could I say schaltet automatisch sich aus or schaltet sich aus automatisch?

The standard, natural order is:

schaltet sich automatisch aus

Some points about word order:

Pronouns (like sich) tend to come early in the “middle field”, usually right after the conjugated verb:
- Der Wasserkocher schaltet sich dann aus.
- Der Wasserkocher schaltet sich automatisch aus.
Adverbs such as automatisch, dann, oft, etc. follow pronouns, but still come before the separable prefix aus.

So:

✅ schaltet sich automatisch aus
✅ schaltet sich dann automatisch aus
❌ schaltet automatisch sich aus (pronoun in the wrong place)
❌ schaltet sich aus automatisch (adverb after the prefix – sounds wrong)

The general pattern in main clauses is:

[Verb] – [pronouns] – [adverbs/other stuff] – [separable prefix]

What exactly does sobald mean here, and how is it different from wenn or als?

sobald means “as soon as” and expresses that one event happens immediately after another.

Der Wasserkocher schaltet sich automatisch aus, sobald das Wasser kocht.
→ The switching off happens as soon as the water is boiling.

Comparison:

wenn = “when / whenever / if” (general time or condition)
- … wenn das Wasser kocht.
  = whenever / when(ever) the water boils.
als = “when” for a one-time event in the past only:
- Als das Wasser kochte, schaltete ich den Wasserkocher aus.

In this sentence, wenn would be grammatically correct:

Der Wasserkocher schaltet sich automatisch aus, wenn das Wasser kocht.

But sobald adds the nuance of immediacy: it stresses that it happens right away.

Why is the verb at the end in sobald das Wasser kocht and not sobald kocht das Wasser?

Because sobald is a subordinating conjunction, and such conjunctions push the verb to the end of the clause.

Pattern:

Main clause (verb in 2nd position):
- Das Wasser kocht.
- Jetzt kocht das Wasser.
Subordinate clause introduced by sobald, wenn, weil, dass, obwohl, etc. (verb at end):
- …, sobald das Wasser kocht.
- …, weil das Wasser kocht.
- …, wenn das Wasser kocht.

So:

❌ sobald kocht das Wasser (wrong word order for a subordinate clause)
✅ sobald das Wasser kocht

If you put the subordinate clause first, the whole sentence looks like this:

Sobald das Wasser kocht, schaltet sich der Wasserkocher automatisch aus.
(Subordinate clause, verb at end → kocht;
then main clause, verb in 2nd position → schaltet.)

Shouldn’t the future tense be used, since the switching off happens after the water starts boiling?

German uses the present tense very often for future events, especially when:

there is a time expression or
the sequence is clear from context (as with sobald here).

So:

Der Wasserkocher schaltet sich automatisch aus, sobald das Wasser kocht.
Literally uses the present tense, but it clearly refers to what will happen once the condition is met.

You could form a future tense:

… sobald das Wasser kochen wird.

However, this sounds unnatural in everyday German. Native speakers overwhelmingly prefer the present tense in this kind of conditional-time sentence.

Does kochen here mean “to cook” or “to boil”? Why das Wasser kocht?

kochen is flexible:

With a direct object it usually means “to cook”:
- Ich koche Nudeln. – I cook pasta.
- Sie kocht Suppe. – She cooks soup.
Without a direct object, describing a liquid, it means “to boil / to be boiling”:
- Das Wasser kocht. – The water is boiling.
- Die Milch kocht. – The milk is boiling.

There is also a more technical verb sieden (“to boil, to simmer”), but for everyday speech about a kettle, Germans almost always say:

Das Wasser kocht.

Could I also say Der Wasserkocher geht automatisch aus, sobald das Wasser kocht? Is there a difference?

Yes, Der Wasserkocher geht automatisch aus, sobald das Wasser kocht is perfectly natural.

The nuance:

sich ausschalten = to switch itself off
→ slightly emphasizes the switching mechanism or action.
ausgehen = to go off / go out
→ focuses more on the result: the device ends up off.

So:

Der Wasserkocher schaltet sich automatisch aus.
– It actively switches itself off (built-in function).
Der Wasserkocher geht automatisch aus.
– It goes off automatically (same idea, but a bit less technical-sounding).

Both are fine; the original just highlights the “switching” idea more clearly.

Why is there a comma before sobald?

German always separates a subordinate clause from the main clause with a comma.

In this sentence:

Main clause: Der Wasserkocher schaltet sich automatisch aus
Subordinate clause: sobald das Wasser kocht

So you must write:

Der Wasserkocher schaltet sich automatisch aus, sobald das Wasser kocht.

If you reverse the order, the comma is still required:

Sobald das Wasser kocht, schaltet sich der Wasserkocher automatisch aus.

This comma rule is mandatory in standard written German.