"They sell powdered spices."

Translation: Ils vendent des épices en poudre.

[clintack]

Is that really how "poudre" is pronounced? It sounds painful.

[CommeuneTexane]

If you ever have a question about pronunciation, I recommend that you check out this site: https://forvo.com/search/poudre/. You can hear various native speakers pronounce the words, both alone and in a sentence.

[steventyp]

ok i don't understand why not "en poudres". isn't the adjective supposed to be plural following the noun?

[CommeuneTexane]

When you have en + a material describing what the noun is made of, the material is invariable.

Here are some examples:
des œufs en chocolat / chocolate eggs
des assiettes en carton / paper plates
un ours en peluche / a plush teddy bear
une écharpe en soie / a silk scarf

[CJ.Dennis]

In English it would be "spices in powder (form)", not spices in powders (form)".