Morgenrutinen tager længere tid, hvis jeg ikke kan finde min nøgle.

Danish normally writes compound nouns as one word. So morgenrutine is morgen + rutine = morning routine.

The ending -n marks the noun as definite singular: the morning routine.

• en rutine = a routine
• rutinen = the routine
• morgenrutinen = the morning routine

Because rutine ends in -e, the definite ending is just -n, not -en written separately.

In Danish, the most normal way to say the + noun is to put the definiteness on the noun itself: morgenrutinen.

You usually use den together with an adjective or for special emphasis:

• morgenrutinen = the morning routine
• den lange morgenrutine = the long morning routine

So in this sentence, morgenrutinen is the natural form.

Yes, it is completely normal. Literally, it means takes longer time, but in natural English we usually just say takes longer.

Danish very often uses tage tid for something requiring time:

• Det tager tid = It takes time
• Det tager lang tid = It takes a long time
• Det tager længere tid = It takes longer

So this is a very standard pattern.

Because in this expression, tid works like an uncountable noun, similar to time in English.

Danish normally says:

• tage tid
• tage lang tid
• tage længere tid

You would not normally say tage en længere tid here. If you want to name a specific amount, then you can use another structure:

• Det tager en time = It takes an hour

Længere is the comparative form, meaning longer.

The basic idea is:

• lang / længe = long
• længere = longer

Here it shows comparison: the routine takes more time than usual or more time than in another situation.

Because hvis jeg ikke kan finde min nøgle is a subordinate clause introduced by hvis.

In Danish, many writers place a comma before subordinate clauses. You may also see variation depending on whether someone uses start comma rules or not. So the comma here is very normal and expected in many texts.

This is about word order in subordinate clauses.

In a main clause, Danish usually has:

• Jeg kan ikke finde min nøgle.

But after a subordinating word like hvis, the word order changes, and ikke usually comes before the finite verb:

• hvis jeg ikke kan finde min nøgle

So:

• main clause: jeg kan ikke finde
• subordinate clause: jeg ikke kan finde

This is one of the most important word-order patterns in Danish.

Kan is a modal verb, and finde is the infinitive.

Together, kan finde means can find or am able to find:

• jeg kan finde = I can find

After modal verbs in Danish, you normally use the infinitive without at:

• jeg kan finde not
• jeg kan at finde

Because a possessive like min already does the job that an article would do.

So Danish says:

• min nøgle = my key not
• min nøglen not
• en min nøgle

With possessives, the noun is usually in the indefinite form:

• min bog
• min nøgle
• mine nøgler

Because sin/sit/sine is only used when the possessor refers back to a third-person subject such as han, hun, den, det, or de.

Here the subject is jeg, so you must use min:

• jeg ... min nøgle

Compare:

• Jeg kan ikke finde min nøgle. = I can’t find my key.
• Han kan ikke finde sin nøgle. = He can’t find his own key.

So sin cannot refer back to jeg.

Hvis is used for a condition: if.

That fits this sentence because the idea is conditional: the routine takes longer if I cannot find my key.

A rough contrast is:

• hvis = if
• når = when

So:

• hvis jeg ikke kan finde min nøgle = if I can’t find my key
• når jeg ikke kan finde min nøgle would sound more like when I can’t find my key, which suggests something more regular or expected.