Breakdown of O saco do supermercado é pesado.
ser
to be
de
of / from / by (means of transport) / wearing (attire)
o supermercado
the supermarket
pesado
heavy
Questions & Answers about O saco do supermercado é pesado.
Why is it saco do supermercado instead of putting the words in the same order as "supermarket bag"?
Why use do here instead of just de?
do is a mandatory contraction of the preposition de (of/from) and the masculine article o (the). If you wanted to talk about a generic supermarket bag, you could say um saco de supermercado. But because we are talking about a specific bag from a specific supermarket, we include the "the" (o), making it do.
Since a bag is usually only heavy temporarily when it is full of groceries, shouldn't the verb be está?
This is an excellent catch! If you are carrying a plastic bag and it feels heavy because of the groceries inside, you would indeed use está (from estar, for temporary states) and say O saco está pesado. Because this sentence uses é (from ser, for permanent characteristics), it implies the bag itself is a heavy object, perhaps a large, thick, heavy-duty reusable bag.
If the sentence was about a box (a caixa) instead of a bag (o saco), what would change?