Learn Hardcore Spanish (Latin America): Antes de que entremos al zoológico, compraré agua fría para todos. - Before we enter the zoo, I will buy cold water for everyone.

In Spanish, certain conjunctions of time—like antes de que, cuando, hasta que—require the subjunctive when they refer to actions that haven’t happened yet. Here’s why:

antes de que introduces a future or pending action (we haven’t entered the zoo yet).
The subjunctive (entremos) expresses that uncertainty or non-realized event.
If the action were habitual or already completed, you’d switch to the indicative.

Could I say antes de entrar al zoológico instead of antes de que entremos al zoológico?

Yes—if the subject of both clauses is the same, you can drop que and use an infinitive:

Correct: Antes de entrar al zoológico, compraré agua fría.
(Here the subject “I” does both “enter” and “buy.”)

But if you want to emphasize the group entering (we) before you buy, or if the subjects differ, use antes de que + subjunctive.

What’s the difference between entremos and entramos?

entremos is the present subjunctive (used for pending or desired actions).
entramos is the present indicative (used for facts or habitual actions).
Since entering the zoo is a future event relative to buying water, Spanish uses entremos.

Why do we contract a + el into al when saying al zoológico?

In Spanish, whenever the preposition a immediately precedes the masculine singular article el, they must contract to al:

a + el parque → al parque
a + el zoológico → al zoológico

This contraction is mandatory; a el is ungrammatical.

Why don’t we use an article before agua fría (“buy cold water”), like el agua fría?

Here agua fría is an indefinite, unspecified quantity (“cold water for everyone”). In Spanish:

When talking about something in general or in unspecified amount, you often omit the article: compraré agua.
If you refer to a specific water (e.g. the bottle you left), you would say el agua fría.

Why does fría have an accent mark?

Spanish accent rules state that words ending in a vowel are stressed on the penultimate syllable by default. Without an accent, fria would be read as FRI-a (stress on the first syllable). The accent on í shifts the stress:

fría → frí-a (correct pronunciation)

Why use the simple future compraré instead of voy a comprar?

Both forms express future actions, but they have slightly different uses:

compraré (simple future) is often more formal or literary; it directly conjugates the verb.
voy a comprar (periphrastic future) is very common in spoken Spanish to indicate a planned or imminent action.

In everyday Latin American usage, voy a comprar agua fría is perfectly natural, but compraré is also correct.

Why is it para todos and not a todos (“for everyone”)?

para indicates purpose or benefit—“for the benefit of everyone.”
a
- indirect object often marks the receiver of an action, but para is more idiomatic when you’re buying something intended for a group’s use.

You could say Voy a comprar agua fría a todos and be understood, but para todos focuses on “for everyone’s enjoyment.”

Can I place the main clause before the subordinate clause?

Yes. You can invert the sentence without changing meaning:

Compraré agua fría para todos antes de que entremos al zoológico.

In that order, the comma before antes is optional, since the main idea comes first.

Is the comma necessary after the subordinate clause?

When a subordinate clause appears at the beginning, Spanish convention uses a comma to separate it from the main clause:

Antes de que entremos al zoológico, compraré agua fría para todos.

If the main clause comes first, the comma is not required:

Comprar é agua fría para todos antes de que entremos al zoológico.