Learn Hardcore Indonesian: Penjaga laboratorium menjelaskan reaksi kimia di tabung kaca. - The laboratory attendant explains the chemical reaction in the glass tube.

Penjaga laboratorium menjelaskan reaksi kimia di tabung kaca.

The laboratory attendant explains the chemical reaction in the glass tube.

Breakdown of Penjaga laboratorium menjelaskan reaksi kimia di tabung kaca.

menjelaskan

to explain

reaksi kimia

the chemical reaction

tabung kaca

the glass tube

penjaga laboratorium

the laboratory attendant

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Questions & Answers about Penjaga laboratorium menjelaskan reaksi kimia di tabung kaca.

What does penjaga laboratorium literally mean, and is it the same as “lab technician” or “lab assistant”?

Literally, penjaga laboratorium is:

penjaga = guard / caretaker / person who looks after something
laboratorium = laboratory

So penjaga laboratorium is “laboratory guard/caretaker,” someone who looks after the lab (security, maintenance, etc.).

For “lab assistant / lab technician,” Indonesian more commonly uses:

asisten laboratorium
petugas laboratorium
teknisi laboratorium

The sentence is grammatically fine, but penjaga laboratorium suggests a caretaker or guard rather than a trained lab technician.

Why is it menjelaskan and not just jelas or menjelas?

The base word is jelas = “clear” (adjective).
To make it into the verb “to explain / to make clear,” Indonesian uses the meN- … -kan pattern:

jelas (clear)
→ menjelaskan (to explain / to make something clear)

So:

jelas = “clear”
- Penjelasannya jelas. = The explanation is clear.
menjelaskan = “to explain”
- Dia menjelaskan reaksi kimia itu. = He/She explained that chemical reaction.

There is no form menjelas; it would be ungrammatical. The causative verb form needs the -kan: menjelaskan.

What is the subject–verb–object structure in this sentence?

The structure is straightforward S–V–O (subject–verb–object) plus a prepositional phrase:

Subject: Penjaga laboratorium
Verb: menjelaskan
Object: reaksi kimia
Prepositional phrase (location): di tabung kaca

So in English-like order:

Penjaga laboratorium (The lab caretaker)
menjelaskan (explained)
reaksi kimia (the chemical reaction)
di tabung kaca (in the glass tube).

Does reaksi kimia mean “chemical reaction” or “chemistry reaction”? Why is the order like that?

Reaksi kimia means “chemical reaction.”

reaksi = reaction
kimia = chemical / chemistry

In Indonesian, adjectives and many descriptive words come after the noun:

reaksi kimia = reaction (that is) chemical
buku merah = red book
air panas = hot water

So reaksi kimia is the normal way to say “chemical reaction,” not kimia reaksi.

Is kimia an adjective here or a noun like “chemistry”?

In Indonesian, kimia can be both:

As a noun (chemistry):
- Saya belajar kimia. = I study chemistry.
As a modifier/adjective-like word (chemical):
- reaksi kimia = chemical reaction
- zat kimia = chemical substance

In reaksi kimia, it functions like an adjective (“chemical”), describing what kind of reaction it is.

What does di tabung kaca mean exactly? Why use di here?

di tabung kaca literally means “in the glass tube” or “inside the glass tube.”

di = at / in / on (location, no movement)
tabung = tube / cylinder
kaca = glass

So di tabung kaca describes the location of the reaction: it is happening in the glass tube.

You use di for a static location:

di meja = on the table
di laboratorium = in the laboratory
di tabung kaca = in the glass tube

How do we know whether it means “the glass tube” or “a glass tube,” since there is no article?

Indonesian does not have articles like “a” or “the.”
The phrase tabung kaca by itself can mean:

a glass tube
the glass tube
glass tubes (in general)

The exact meaning depends on context. If you really need to specify:

sebuah tabung kaca = a (single) glass tube
tabung kaca itu = that / the glass tube
tabung-tabung kaca = glass tubes (plural, but still no “the/a”)

In your sentence, di tabung kaca could be translated as “in a glass tube” or “in the glass tube” depending on the context given.

Is tabung kaca the standard way to say “test tube” in Indonesian?

Literally, tabung kaca is “glass tube.” It could describe any kind of glass tube, not necessarily a laboratory test tube.

The more specific and more common term for a lab test tube is:

tabung reaksi = test tube (literally “reaction tube”)

So:

reaksi kimia di tabung kaca = chemical reaction in a glass tube (general)
reaksi kimia di tabung reaksi = chemical reaction in a test tube (more specific to lab equipment)

Where does di tabung kaca attach in meaning? Is it modifying reaksi kimia or menjelaskan?

By default, di tabung kaca is understood to modify the nearest relevant phrase, which is reaksi kimia:

menjelaskan [reaksi kimia di tabung kaca]
= explained the chemical reaction in the glass tube

So the reaction is in the glass tube.

If you wanted to emphasize that the explaining took place in the glass tube (which is odd), you would normally change the sentence structure or add clarification. In normal interpretation, it’s:

He explained the chemical reaction (that occurs) in the glass tube.

How can we tell whether the sentence is past, present, or future? It just says menjelaskan.

Indonesian verbs usually do not change form for tense.
Menjelaskan can mean:

explains / is explaining (present)
explained (past)
even future in some contexts (“will explain”)

Tense is shown by time words or context, for example:

Tadi penjaga laboratorium menjelaskan reaksi kimia di tabung kaca.
= Earlier, the lab caretaker explained the chemical reaction in the glass tube.
Sekarang penjaga laboratorium menjelaskan reaksi kimia di tabung kaca.
= Now, the lab caretaker is explaining the chemical reaction in the glass tube.
Besok penjaga laboratorium akan menjelaskan reaksi kimia di tabung kaca.
= Tomorrow, the lab caretaker will explain the chemical reaction in the glass tube.

So without extra context, menjelaskan is neutral for tense.

Could we say penjaga di laboratorium instead of penjaga laboratorium? What’s the difference?

Both are grammatical, but they feel a bit different:

penjaga laboratorium
- Reads as one noun phrase: “lab caretaker,” “laboratory guard.”
- The second noun (laboratorium) specifies what kind of penjaga it is.
penjaga di laboratorium
- Literally “a guard/caretaker at the laboratory.”
- Emphasizes location more than identity; he might be a security guard working at that place.

In your sentence, penjaga laboratorium sounds more like a specific role: “the person whose job is to look after the lab.”