Question
Question 4 of 16 You want to measure the heat given off during four different reactions Each of the reactions takes place in a flask with a lid. Why must each flask have a lid on? so that oxygen doesn't affect the reactions so that contaminants do not foll into the reactions to contain the heat equally in each reaction so that the reaction doesn't get in your eyes
Answer
4.3
(212 Votes)
Laura
Master · Tutor for 5 years
Answer
C
Explanation
The question asks why a flask with a lid is needed during a reaction. The main purpose of having a lid on a flask is to prevent external interference, allowing the reaction to proceed as expected. Here are the implications of the choices given: Choice one suggests prevention of oxidation, which can affect subsequent reactions because oxidation can speed up some reactions which can contaminate results. Choice two suggests it's to prevent contaminants, which invalidates the results because an additional unknown factor has then become part of the chemical reaction. Choice three suggests that lid could allow heat to be contained equally in each reaction; but in an exothermic reaction, such as the question suggests ('heat given off'), heat will be generated from the reaction itself, so putting a lid will assist in measuring the heat given off in the reaction without heat loss. Finally, choice four is more for safety's sake - having a lid staggers the projection of a reactive substance, if any.