Antes de eu sair, vou lavar as mãos de novo.

After antes de, Portuguese very often uses the infinitive: antes de sair, antes de comer, antes de dormir.

In this sentence, the infinitive has an explicit subject, so you get antes de eu sair. This is a case of the personal infinitive, which is something Portuguese has and English does not really have in the same way.

So:

• antes de sair = before leaving / before I leave
• antes de eu sair = before I leave

Both are possible, but the second one spells out who is doing the leaving.

Because Portuguese can use an infinitive with its own subject. That is called the personal infinitive.

Here, eu is the subject of sair:

• eu sair = I leave / for me to leave

This is very common after prepositions such as de, para, sem, and others:

• para eu fazer = for me to do
• sem eu ver = without me seeing
• antes de eu sair = before I leave

Normally, after a preposition, Portuguese often uses object-style pronouns such as mim, ti, etc. But when the pronoun is the subject of an infinitive, Portuguese uses the subject form:

• para eu fazer
• sem eu saber
• antes de eu sair

So here, eu is correct because eu is the one doing sair.

Compare:

• Isso é para mim. = This is for me.
• Isso é para eu fazer. = This is for me to do.

In the second sentence, eu is the subject of fazer.

Because de + eu does not contract in standard Portuguese.

Portuguese has many contractions, such as:

• de + o = do
• de + a = da
• de + ele = dele

But with eu, the normal form is simply de eu:

• antes de eu sair
• de eu falar isso...

So even though it may feel unusual to an English speaker, de eu is the standard form.

Yes. That is very natural, and many speakers would actually prefer it when the subject is clearly the same person in both parts of the sentence.

So these are both possible:

• Antes de eu sair, vou lavar as mãos de novo.
• Antes de sair, vou lavar as mãos de novo.

The version with eu is a bit more explicit. The version without eu is often more streamlined.

Because in Brazilian Portuguese, ir + infinitive is extremely common for talking about the future, especially in everyday speech.

So:

• vou lavar = I’m going to wash / I will wash
• lavarei = I will wash

Both are correct, but vou lavar sounds more natural and conversational in Brazil. Lavarei is more formal, more written, or sometimes more emphatic.

Portuguese often uses the definite article with body parts when it is already obvious whose body part is meant.

So Portuguese prefers:

• lavar as mãos = wash the hands / wash one’s hands
• fechar os olhos = close the eyes
• quebrei o braço = I broke my arm

In English, we usually use my, your, his, etc. Portuguese often does not need that here.

You can say minhas mãos, but it usually adds emphasis, contrast, or sounds less neutral in a basic sentence.

Because lavar as mãos already works naturally without a reflexive pronoun.

In Portuguese:

• lavar as mãos = wash one’s hands
• me lavar = wash myself

These are not exactly the same thing.

So:

• vou lavar as mãos = I’m going to wash my hands
• vou me lavar = I’m going to wash myself / clean myself up

If you add me in the original sentence, it no longer sounds like the most natural way to say wash my hands.

Because de novo is a very common and natural way to say again in Brazilian Portuguese.

So:

• de novo = again
• novamente = again

Both are correct, but de novo is more common in everyday speech. Novamente can sound a bit more formal or written.

In this sentence, de novo simply means again, not necessarily from the beginning.

Yes. Both are possible:

• Antes de eu sair...
• Antes que eu saia...

The second one uses antes que + subjunctive, which is also correct because it refers to a future action that has not happened yet.

In Brazilian Portuguese, antes de + infinitive is often very common and natural, especially when the structure is simple. Antes que eu saia may sound a little more formal or more syntactically marked, depending on context.

Yes. Mão is a feminine noun:

• a mão = the hand
• as mãos = the hands

This can surprise learners because many nouns ending in -o are masculine, but mão is an exception.

Its plural is also irregular:

• mão → mãos

not mões.

So lavar as mãos is the correct form.

Because Antes de eu sair is an introductory clause placed before the main clause.

So the sentence is structured like this:

• Antes de eu sair, = before I leave
• vou lavar as mãos de novo. = I’m going to wash my hands again.

In Portuguese, it is very normal to use a comma when this kind of subordinate clause comes first.

If you put that clause at the end, the comma is usually not needed:

• Vou lavar as mãos de novo antes de eu sair.