I had a quiz today and one of the multiple choice questions was something like, "find the final temperature of aluminum when it is cooled" and then it gave you the specific heat capacity of aluminum, the mass of the aluminum, initial temperature, and enthalpy change.
One of the options was that there was insufficient information because you need the mass of H2O used to cool the aluminum.
I chose that one... Is that right?
I chose it because I remember my teacher explaining that when you have a solid and a solution reacting, you only use the mass of the solution when doing Q=mc(detlaT). She said, "to explain it simply... What are you putting the thermometer in? The solid or the solution? You're not going to stick a thermometer into a solid." So I thought you'd need the mass of H2O because you can't use the mass of Al... But I overheard other people talking about it and I think a bunch of people calculated an actual value...
I just want to know if I got it right or wrong; it's been bugging me all day.
"Something like" isn't enough for me to know.
q = mass Al x specific heat Al x (Tfinal-Tinitial)
If you used H2O to cool the Al you would need the mas of the H2O and the initial T of the H2O, then you could do the final T. Of course the final T of the water will be the same as the final T of the Al.
enthlapy = heat change.
enthalpy change=mass*specheat*deltaTemp
Thanks; I obviously got it wrong, but what was my teacher talking about when she said that when you have a solid reacting, you don't use the mass of the solid for Q=mc(deltaT), only the mass of liquids or solutions? Why wouldn't that apply in this case?
Based on your explanation, it seems like you made the right choice by selecting the option that there was insufficient information because you need the mass of H2O used to cool the aluminum. Allow me to explain the reasoning behind the answer.
In order to calculate the final temperature when a substance is cooled, the formula Q = mcΔT is often used, where Q represents the heat transferred, m is the mass of the substance, c is the specific heat capacity, and ΔT is the change in temperature. However, in this specific scenario, the problem mentions that the aluminum is being cooled using H2O (water).
Now, when a solid, such as aluminum, is being cooled by a liquid, like water, the mass of the liquid (in this case, H2O) is crucial in determining the final temperature. This is because the heat transferred from the aluminum to the water depends on the mass of the water as well.
Hence, without knowing the mass of H2O used to cool the aluminum, it is indeed not possible to calculate the final temperature accurately. Therefore, the option stating insufficient information due to the missing mass of H2O is the correct choice.
It's great that you remembered your teacher's explanation about the use of mass in such scenarios. It shows an understanding of the concept and an ability to apply the knowledge to the multiple-choice question.