Long lasting dry ice I have a chemistry question but I'm not sure which subtopic it'd go under, so I'm asking it here. I'd really appreciate any help I can get, if you have an answer, or if you can tell me where I can find the answer. I should also mention I don't know anything about chemistry, so I'm sorry if my question sounds stupid :-)

I was wondering if it's possible for dry ice (the industrial ones or those that are sold at stores) to stay cold/frozen in a rather warm/hot room temperature for around 2-4 hours. Let's say blocks of 3x3x4 inches. I just want to know if that's feasible or not.
Put them in a container. It could be open at the top, but should be enclosed in the bottom.

The dry ice will insulate itself with a layer of cold air/CO2. As long as they are not under direct heating illumination or the convection of air in the room is high, this should be sufficient for a suitable mass of dry ice.

We routinely keep dry ice in "open" unpowered freezers at my lab (with no refrigeration) for the duration of the day. If your room is very humid you can get buildup of ice / condensed water, so some insulation around the container might be prudent.