It would be very unadvisable to place a can of soup over a campfire without venting the can. As the can heats up, it may explode. The kinetic-molecular theory explains why. The air inside the rigid can of soup is given more kinetic energy by the heat coming from the campfire. The kinetic energy causes the air molecules to move faster and they impact the container walls more frequently and with more force. The increase in pressure inside may eventually exceed the strength of the can and it will explode. An additional factor is that the soup may begin boiling which will then aid even more gas and more pressure to the inside of the can.
The turkey was almost done cooking. Beth pulled it out of the oven to baste one last time. She picked up her turkey baster and squeezed the bulb . She the inserted the open stem end into the turkey broth while releasing the bulb and watched as the liquid was pulled inside. As she squeezing the bulb again the broth was pushed out of the opening and onto the turkey.
Was the air pressure inside and outside the baster unequal before or after squeezing the bulb?