exothermic

[Naana Boateng 1I]

If a flask turns cold, can you automatically assume that the reaction is exothermic?

[Sarah Sharma 2J]

If it turns cold, it means that the reaction in the flask absorbed heat from its surroundings and would therefore be endothermic! When a reaction is exothermic the flask should feel warm due to the release of heat/energy.

[Josh Moy 1H]

If a flask turns cold its endothermic because it absorbs heat

[Justin Chu 1G]

But if it gets colder, doesn't it mean that it is losing heat?

[Adam Enomoto 1L]

The flask is the surroundings and the reaction is the system. When there's an exothermic reaction, the flask will heat up. If there's an endothermic reaction the flask will cool down because heat is going to the system and away from the surroundings

[Christy Zhao 1H]

Since the flask is getting colder, it is an endothermic reaction because the flask(as the surroundings) is losing heat. Therefore, the heat from the flask is going into the reaction.