En lugar de usar un recipiente abierto, elegimos un recipiente hermético.

En lugar de means instead of.

It is a fixed expression. After it, Spanish usually uses:

• a noun: En lugar de azúcar, usamos miel.
  = Instead of sugar, we use honey.
• an infinitive: En lugar de usar...
  = Instead of using...

So in your sentence, En lugar de usar un recipiente abierto... means Instead of using an open container...

Because after en lugar de, Spanish normally uses the infinitive when talking about an action in a general way.

• En lugar de usar = instead of using
• not en lugar de usamos

This is similar to English, where instead of is often followed by -ing:

• instead of using
• Spanish uses the infinitive: en lugar de usar

Recipiente is a general word for a container, vessel, or receptacle.

It is broader than some other Spanish words:

• recipiente = general container
• botella = bottle
• caja = box
• tarro / frasco = jar
• envase = packaging/container, often for products
• contenedor = larger container, bin, shipping container, etc.

So recipiente is a neutral, flexible word here.

In Spanish, most descriptive adjectives normally go after the noun.

• un recipiente abierto
• un recipiente hermético

This is the most neutral and standard order.

If an adjective goes before the noun, it often sounds more literary, emphatic, or changes nuance. In this sentence, the normal order is exactly what you would expect.

Not exactly. Hermético means airtight or sealed so that air cannot get in or out.

So:

• cerrado = closed
• hermético = airtight / sealed

A container can be cerrado without being hermético.
For example, a lid may be on, but if air can still pass through, it is closed but not truly airtight.

Spanish often repeats the noun where English might avoid repetition.

So this is very natural:

• un recipiente abierto, elegimos un recipiente hermético

You could sometimes shorten things in Spanish, but repeating the noun sounds clear and natural here. It contrasts the two types of container very neatly:

• recipiente abierto
• recipiente hermético

That repetition is not awkward in Spanish.

Elegimos is ambiguous by itself. It can be:

• present: we choose
• preterite: we chose

This happens with some -ir verbs in the nosotros form.

So without more context, the sentence could mean either:

• Instead of using an open container, we choose an airtight container.
• Instead of using an open container, we chose an airtight container.

Usually the wider context tells you which one is meant.

They are very similar and often both mean to choose.

• elegir
• escoger

In many contexts, they are interchangeable. Elegir is extremely common and sounds perfectly natural here.

You could also say:

• En lugar de usar un recipiente abierto, escogimos un recipiente hermético.

That would also be correct.

The comma separates the introductory phrase from the main clause.

• En lugar de usar un recipiente abierto, = introductory idea
• elegimos un recipiente hermético. = main statement

In English, you often do the same:

• Instead of using an open container, we chose an airtight container.

So the comma helps readability and structure.

No. In standard Spanish, h is silent.

So hermético is pronounced roughly like er-MÉ-ti-co.

Also note the written accent:

• hermético

The stress falls on mé.

Because recipiente is a masculine singular noun.

So the article and adjectives must match it:

• un recipiente abierto
• un recipiente hermético

Agreement works like this:

• recipiente = masculine singular
• abierto / hermético = masculine singular forms

If the noun were feminine, the forms would change accordingly.

Yes. En vez de and en lugar de both mean instead of and are often interchangeable.

So you can say:

• En lugar de usar un recipiente abierto...
• En vez de usar un recipiente abierto...

Both are correct and natural. En lugar de can sound a little more formal or neutral in some contexts, but the difference is usually small.

Both work.

• usar = to use
• utilizar = to utilize / use

In everyday Spanish, usar is often the simpler, more common choice.
Utilizar can sound a little more formal or technical.

So:

• En lugar de usar un recipiente abierto...
  is very natural.

And this is also correct:

• En lugar de utilizar un recipiente abierto...