Auf dem Verdampfer liegt Eis.

Because this sentence describes a location, not movement.

• auf + dative = location, meaning on or on top of
• auf + accusative = movement toward a surface, meaning onto

So:

• Auf dem Verdampfer liegt Eis. = Ice is lying on the evaporator.
• Das Eis fällt auf den Verdampfer. = The ice falls onto the evaporator.

Here, the ice is already there, so German uses the dative: dem Verdampfer.

dem is the dative singular form of the definite article for masculine and neuter nouns.

The noun Verdampfer is masculine: der Verdampfer.

Its forms are:

• nominative: der Verdampfer
• accusative: den Verdampfer
• dative: dem Verdampfer

Since auf takes the dative here, you get auf dem Verdampfer.

Verdampfer is masculine: der Verdampfer.

You usually learn noun gender together with the noun, since it is not always fully predictable. That said, many nouns ending in -er are masculine, especially nouns for devices, tools, or people. So der Verdampfer fits a common pattern.

German often prefers a position verb where English might simply use to be.

Here, liegen means to lie or to be lying/resting. It is used for things that are in a horizontal or resting position.

So Auf dem Verdampfer liegt Eis is more literally:

• Ice lies on the evaporator

In natural English, you would usually say:

• There is ice on the evaporator
• Ice is on the evaporator

German often sounds more natural with liegen in sentences like this.

This is a very common learner question.

• liegen = to lie, to be lying somewhere

  • no direct object
  • describes a state or position

• legen = to lay, to put something somewhere

  • takes a direct object
  • describes an action

Compare:

• Das Eis liegt auf dem Verdampfer.
  The ice is lying on the evaporator.

• Jemand legt das Eis auf den Verdampfer.
  Someone puts the ice onto the evaporator.

A helpful pattern:

• liegen = position
• legen = caused movement into that position

German uses verb-second word order in main clauses. That means the finite verb must come in the second position, but the first position can be taken by different sentence elements.

So both of these are grammatically correct:

• Auf dem Verdampfer liegt Eis.
• Eis liegt auf dem Verdampfer.

In the version you were given, Auf dem Verdampfer is placed first for emphasis or because the speaker wants to start with the location. Once that phrase is in first position, the verb must come next:

• Auf dem Verdampfer | liegt | Eis

So the subject Eis comes after the verb.

Yes. Eis is the subject.

German does not rely as heavily on word order as English to show who the subject is. Here, the clues are:

• the sentence is a main clause with verb-second order
• liegt is singular
• Eis is the thing that is lying there

So even though Eis comes after the verb, it is still the subject.

Because Eis is being used as an uncountable mass noun here, similar to English ice.

German often omits the article with mass nouns when speaking generally or introducing some amount of a substance:

• Wasser ist kalt.
• Milch steht im Kühlschrank.
• Auf dem Verdampfer liegt Eis.

If you say das Eis, that can sound more specific:

• Das Eis auf dem Verdampfer ist dick.
  The ice on the evaporator is thick.

So the version without an article is completely natural here.

Eis is in the nominative case because it is the subject of the sentence.

In this sentence:

• Auf dem Verdampfer = prepositional phrase in the dative
• liegt = verb
• Eis = subject in the nominative

With Eis, the nominative and accusative forms look the same, so the form itself does not change here.

Here, auf means on, specifically on the surface of something.

So auf dem Verdampfer means:

• on the evaporator
• on top of the evaporator

It is a very common preposition, but it can have different meanings depending on context and case.

Examples:

• Das Buch liegt auf dem Tisch. = The book is on the table.
• Ich lege das Buch auf den Tisch. = I put the book on the table.

Same preposition, different case depending on whether it describes location or movement.

Yes, absolutely.

Even though the German literally uses liegt (lies / is lying), a natural English translation is often:

• There is ice on the evaporator.

That is often the best way to express the meaning in normal English. German and English do not always choose the same kind of verb in these everyday location sentences.

It is more of a technical or semi-technical noun than an everyday household word for many speakers.

It comes from the verb verdampfen, meaning to evaporate or to vaporize, and der Verdampfer means evaporator.

So this sentence sounds like something from:

• refrigeration
• air conditioning
• appliance repair
• technical documentation

Yes, in colloquial spoken German, some speakers may say aufm as a contraction of auf dem.

However:

• auf dem is the normal standard written form
• aufm is informal and mainly spoken or very casual writing

So for learners, it is best to use auf dem unless you are specifically trying to understand casual speech.

Because in German, all nouns are capitalized.

So:

• der Verdampfer
• das Eis

This is one of the most noticeable spelling differences between German and English. Verbs and prepositions like liegt and auf are not capitalized unless they begin the sentence.