A definite area or space where thermodynamic process takes place?

Thermodynamic system

There are three different products that can be used to make slime less sticky. the first is borax. directions for mixing slime with borax is to put the slime in a bowl or container. flatten the slime, but leave an area of the bowl slime free where you will pour the borax liquid. pour in 1/2 a teaspoon, and then move the slime over into the liquid until it is mixed. play with the slime for 3-5 minutes until it reaches the consistency you prefer. tide is another product that can be used to make slime less sticky. put the slime in a container and flatten on the bottom of the container. put 1/2 a teaspoon of tide on the slime. take the slime in your hand to mix over 2 minutes. if the slime is too sticky, repeat above with another 1/2 teaspoon of tide. mix to your preferred consistency and stickiness. to use liquid starch, spread the slime on the bottom of a container and poke a hole in the middle the size of your finger. put pour in liquid starch and fold slime over the hole. then pick up the slime and manipulate in your hand for 5-7 minutes until the starch is mixed.