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 (because and why).
Let's see the difference between porqué and por que:
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.
2. 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.
- Porqué = a reason, a cause (noun)
- Por que = for which, that, why (preposition + conjunction)