Find how much marinade you need for a given meat weight.
How much marinade you need depends far more on the container than on the food. A zip bag can be pressed flat so the liquid contacts every surface, and about 250 ml per kilogram is plenty for a wet marinade. The same food in a deep bowl needs half again as much simply to reach a depth that covers it, which is wasted liquid you will pour away. Brines are a different scale entirely, needing full submersion at roughly 1200 ml per kilogram, and their salt concentration is what actually does the work — a 5 to 6 percent solution is standard for poultry and pork.
Marinade volume
ml = weight kg x base ml per kg x vessel factor
Salt
Salt g = marinade ml x salt concentration%
Marinate raw meat, poultry and fish in the refrigerator, never at room temperature, and discard used marinade that has been in contact with raw food unless you boil it thoroughly first. Never reuse marinade as a sauce without boiling. Follow your national food safety authority's guidance on handling raw protein.
Because you can press the air out and fold the bag around the food, so every surface is in contact with liquid. A dish or bowl requires enough volume to reach a covering depth, most of which never touches the food and gets discarded.
Yes. Acidic marinades containing citrus, vinegar or wine begin denaturing the surface proteins, and after several hours the texture turns mushy and chalky rather than tender. Delicate fish needs 15 to 30 minutes; robust cuts tolerate overnight. Salt-only brines are much more forgiving.