xiān bǎ shuǐ zhǔkāi.

先 means first or before doing the next step. It tells you this action happens earlier than another action, even if the next action is not stated.

So 先把水煮开 means something like:

• First, boil the water
• Boil the water first

In instructions, recipes, and directions, 先 is very common.

把 marks the object and brings it before the verb so the speaker can focus on what happens to that object.

Pattern:

把 + object + verb + result/complement

Here:

• 把水煮开
• object: 水
• action + result: 煮开

This structure often appears when the speaker wants to show that the action causes a clear result or change to the object.

So this sentence is not just about the action boil; it emphasizes the result that the water becomes boiled / reaches a boil.

煮水 is possible, but it is more general: to boil water.

把水煮开 is more specific and result-focused. It means boil the water until it reaches the boiling point / until it boils.

Compare:

• 煮水 = boil water
• 把水煮开 = boil the water so that it boils

The 把 sentence is especially natural when giving instructions or telling someone what to do with a specific thing.

煮开 is 煮 + 开.

• 煮 = to boil / cook in liquid
• 开 here is a result complement

In this kind of sentence, 开 does not mean open. It means something has reached the state of opening up / starting / becoming fully active, and with liquids it often means coming to a boil.

So 煮开 means:

• boil until it boils
• bring to a boil

This is a very common pattern in Mandarin:
verb + result complement

The subject is omitted. That is very common in Mandarin, especially in:

• instructions
• recipes
• commands
• conversations where the subject is obvious

The full sentence could be:

• 你先把水煮开。 = You boil the water first.
• 我们先把水煮开。 = Let’s boil the water first.

But in many contexts, Mandarin simply leaves the subject out.

Usually, 煮开水 is not the best replacement here.

Why? Because 开水 is already a word meaning boiled water. So 煮开水 can sound ambiguous, as if you are saying boil boiled water or using a less natural phrasing.

More natural options are:

• 先把水煮开
• 先烧开水 in some contexts
• 先把水烧开

So for this sentence, 先把水煮开 is a very good and natural choice.

Both can mean bring to a boil, and both are common.

• 煮开 focuses on boiling as a cooking process
• 烧开 is also very common for heating water until it boils

For water, many speakers often say:

• 把水烧开
• 把水煮开

Both are natural. The exact preference can vary by region and context.

Yes, but the meaning or tone changes depending on context.

• 先把水煮开。
  plain instruction: Boil the water first.

• 先把水煮开了。
  can suggest get the water boiled first, often with a sense of completing that step before something else

In many instruction sentences, the version without 了 is the most neutral and common.

If you are talking about a completed action, you might say:

• 我先把水煮开了。 = I boiled the water first.

So 了 is possible, but it is not necessary in the basic imperative/instruction form.

The sentence follows a common Mandarin order:

adverb + 把 + object + verb + result

So here:

• 先 = adverb
• 把水 = object phrase
• 煮开 = verb + result

This order is very typical in Mandarin when using 把.

For example:

• 先把门打开。 = Open the door first.
• 先把饭吃完。 = Finish the meal first.

The 把 structure has its own grammar pattern, so you usually do not move things around freely.

Sometimes yes, but not every position sounds equally natural.

Very natural:

• 先把水煮开。
• 你先把水煮开。

Also possible in some contexts:

• 把水先煮开。

But 先把水煮开 is usually the most straightforward and natural form for a simple instruction.

A good rule for learners is:

• put 先 before the main action phrase
• if there is a subject, usually: subject + 先 + ...

Example:

• 你先把水煮开。

Yes. In careful citation form, 把 is third tone: bǎ.

But in connected speech, when a third-tone syllable comes before another third-tone syllable, the first one usually changes to a rising tone-like pronunciation.

Here:

• 把 = third tone
• 水 = third tone

So 把水 is commonly pronounced more like:

• bá shuǐ

This is standard third-tone sandhi.

The written pinyin still stays bǎ shuǐ, but the actual pronunciation changes in normal speech.

It can be understood as an instruction or command, depending on context.

Without a subject, Mandarin often uses short sentences like this for:

• recipes
• lab instructions
• giving directions
• telling someone what to do next

So 先把水煮开。 most naturally sounds like:

• an instruction
• a command
• a step in a process

The tone of voice and context decide whether it feels firm, neutral, or polite.

This is because the sentence uses the 把-construction, which changes the usual order.

In a basic sentence, Mandarin often uses:

• verb + object

Example:

• 煮水

But with 把, the object is moved before the verb:

• 把水煮开

This pattern is especially common when the verb is followed by a result, direction, or other complement.

So the object appears before the verb not because Mandarin always does that, but because 把 specifically creates this structure.