Eu acabei de lavar o liquidificador porque a vitamina caiu no chão.

Acabei de + infinitive is a very common Portuguese structure meaning have just done something or just did something.

So:

• Eu acabei de lavar o liquidificador = I just washed the blender

It does not literally mean I finished of washing in natural English, even though acabar by itself often relates to finishing.

A few examples:

• Acabei de comer. = I just ate.
• Ela acabou de sair. = She just left.
• A gente acabou de chegar. = We just arrived.

After acabar de, Portuguese uses the infinitive:

• acabei de lavar
• acabou de sair
• acabamos de chegar

So lavar is correct because it is the infinitive to wash.

Lavado is a past participle, like washed, and it would be used in different structures, such as:

• O liquidificador foi lavado. = The blender was washed.
• Eu tinha lavado o liquidificador. = I had washed the blender.

Yes, you often can leave it out.

Portuguese commonly drops subject pronouns when the verb already makes the subject clear:

• Acabei de lavar o liquidificador...

This still clearly means I just washed the blender... because acabei shows I.

Including Eu adds a little emphasis, contrast, or clarity. For example:

• Eu acabei de lavar o liquidificador, não ele. = I just washed the blender, not him.

So in this sentence, Eu is correct but not necessary.

In Brazilian Portuguese, vitamina can mean a fruit smoothie or blended drink, often made with fruit and milk.

So in this sentence, a vitamina is probably something like a smoothie, not a vitamin pill or nutrient.

This can confuse English speakers because the most obvious meaning of vitamina looks like vitamin in English, but in everyday Brazilian Portuguese it can also refer to a drink.

Examples:

• Vou tomar uma vitamina de banana. = I’m going to have a banana smoothie.
• Ela fez uma vitamina de mamão. = She made a papaya smoothie.

Portuguese uses definite articles much more often than English.

So o liquidificador literally means the blender, and that sounds very natural in Portuguese even when English might sometimes say just the blender or refer more generally.

In Portuguese, it is very normal to specify the noun with an article:

• lavei o carro = I washed the car
• fechei a porta = I closed the door
• peguei o celular = I grabbed the phone

Using liquidificador without the article would usually sound less natural in this kind of sentence.

Caiu is the preterite of cair (to fall).

It refers to a completed action in the past:

• a vitamina caiu no chão = the smoothie fell onto the floor

This is the tense most commonly used for a single finished event in the past.

More examples:

• O copo caiu. = The glass fell.
• Ela caiu da cadeira. = She fell off the chair.
• Meu celular caiu na água. = My phone fell in the water.

Because no is the contraction of:

• em + o = no

So:

• no chão = on the floor / onto the floor

This kind of contraction is extremely common in Portuguese.

Other examples:

• na mesa = em + a mesa
• dos livros = de + os livros
• pela porta = por + a porta

So caiu no chão is the natural form, not caiu em o chão.

Porque means because when giving a reason.

So:

• ...porque a vitamina caiu no chão. = ...because the smoothie fell on the floor.

English speakers often get confused because Portuguese has several similar forms:

• porque = because
• por que = why / for what reason
• por quê = why at the end of a question
• porquê = the reason (a noun)

In this sentence, it is giving the reason for washing the blender, so porque is the correct choice.

Both can express recent past, but acabei de lavar strongly emphasizes that the action happened just now.

Compare:

• Acabei de lavar o liquidificador. = I just washed the blender.
• Lavei o liquidificador agora. = I washed the blender now / just now.

The first one is more idiomatic and more commonly used for have just done in Portuguese.

So if you want the natural equivalent of English I just washed..., acabei de + infinitive is often the best choice.

You could say it, but the nuance is a little different.

• Acabei de lavar = I just washed / I have just washed
• Terminei de lavar = I finished washing

Terminei de lavar focuses more on the completion of the task.
Acabei de lavar focuses more on how recent the action is.

So in this sentence, acabei de lavar is the more natural choice if the idea is I just washed it because the smoothie fell on the floor.

Portuguese can describe this situation in more than one way.

Cair no chão means to fall onto the floor, and it sounds natural if the drink fell or ended up on the floor.

You could also hear related ideas with derramar:

• A vitamina derramou no chão. = The smoothie spilled on the floor.
• Eu derramei a vitamina no chão. = I spilled the smoothie on the floor.

The difference is:

• cair emphasizes falling
• derramar emphasizes spilling

In everyday speech, either idea may fit depending on what actually happened.

Yes, in this sentence liquidificador means blender.

It is the normal Brazilian Portuguese word for the kitchen appliance used to blend things like smoothies, soups, and shakes.

Example:

• Vou colocar a fruta no liquidificador. = I’m going to put the fruit in the blender.

So this is a straightforward vocabulary match.

It would sound very natural:

• Acabei de lavar o liquidificador porque a vitamina caiu no chão.

In fact, many native speakers would probably say it this way unless they want to emphasize I specifically.

Both versions are correct:

• Eu acabei de lavar...
• Acabei de lavar...

The second is often more natural in casual conversation.