Mi silla gris está en la cocina.

In Spanish mi is a possessive adjective that always comes before the noun and doesn’t change for gender (only for number: mis). You use mi silla to mean “my chair.”
Mío, mía, míos, mías are possessive pronouns or post-nominal adjectives, used with or without an article after the noun (e.g. la silla mía or esa silla es mía), and often sound more emphatic or formal.

Most descriptive adjectives in Spanish—especially colors, shapes, nationalities—follow the noun:
• silla gris (gray chair)
• pared blanca (white wall)
Putting them before can add stylistic nuance or emphasis, but the neutral word order is noun + adjective.

Adjectives ending in -e or a consonant are invariable for gender—they have one form for both masculine and feminine. They only change for number:
• singular: gris
• plural: grises
Other adjectives ending in -o (like rojo) do change: rojo/roja/rojos/rojas.

Spanish uses two verbs for “to be”:
• ser (es) for permanent traits, identity, origin, time.
• estar (está) for temporary states, emotions, and locations.
Since location is considered a temporary condition, you always say está en la cocina (“it is in the kitchen”).

En is the standard preposition for indicating static location:
• en la casa, en el carro, en el parque.
If there’s movement toward a place, you’d use a: voy a la cocina (“I’m going to the kitchen”).

Spanish normally uses definite articles before rooms, body parts, or objects:
• la cocina, la puerta, el corazón.
This differs from English, which often omits “the.” One exception is en casa, where Spanish drops la (“at home”).