Heat Capacity question. (1 Viewer)

[Willohfish]

This might be a stupid question, but our teacher never really explained how he got this answer.

When burning alcohols, we used aluminium cans to hold the water we were heating. He then told us that the Aluminium in the can was equivalent to a certain amount of water in terms of heat capacity, before he quickly moved on to the rest of the experiment. How did he work this out? Did I miss something in class? Because I don't remember ever having to use the heat capacities of materials other than water.

Also, how would you calculate energy produced per gram, or per mole?

 

[Ishynooshy]

Aluminium definitely doesn't have the same heat capacity as water (Al: 0.9J/gK, H20: 4.18J/gK). What your teacher might have meant is that the change in temperature of the aluminium can is the be assumed to be the same as the change in temperature of the water.

This is clearly flawed, but there isn't an accurate way to measure the temperature change in the can and this assumption does help to simplify the calculations.

This is what I was told when doing this module. It might be a good idea to actually ask your chemistry teacher what he really meant.

 

[scroates]

Aluminium definitely doesn't have the same heat capacity as water (Al: 0.9J/gK, H20: 4.18J/gK). What your teacher might have meant is that the change in temperature of the aluminium can is the be assumed to be the same as the change in temperature of the water.

This is clearly flawed, but there isn't an accurate way to measure the temperature change in the can and this assumption does help to simplify the calculations.

This is what I was told when doing this module. It might be a good idea to actually ask your chemistry teacher what he really meant.

what you are talking about is "specific heat capacity", it is different to "heat capacity". Heat capacity has units J/K.