Difference between porqué and por que (noun vs preposition + conjunction)

These two words, porqué and por que, although they look nearly the same, have two different functions in a sentence.

Note that porqué and por que, are different from por qué and porque which you are already familiar with from Difference between porque and por qué in Spanish (because and why).

Let's see the difference between porqué and por que:

PORQUÉ

Porqué is written as one word with a written accent and is a masculine noun.

As a noun, any associated article (el, los, un, unos) or other determiner such as possesive adjectives (mi, tu, su, etc.) must agree. 

Porqué can be used in its plural form porqués, as you can see in the second example above.

POR QUE

Por que  is written as two words with no written accent. It is formed by the preposition por and conjunction que, and its translation is for which. However, it is often translated as "that" or "why". You can also use por que when a phrasal verb like preocuparse por, luchar por, etc., is naturally followed by que.

Sometimes por que is a combination of the preposition por + relative pronoun que. In this case it is more common to use it with the article (por el que, por la que...), but it could also be omitted.

See also:

• Difference between porque and por qué in Spanish (because and why)
• Written accents in Spanish