Jump to content

ap chem: q rxn, q soln, and Calorimeters

Featured Replies

I have water and an unknown metal. I know the masses of both, as well as the temperature changes. I know the specific heat of water, but I have to determine the specific heat of the unknown metal. There is a equation that goes as follows: q rxn = -(q soln + (C * delta T)). The q rxn would stand for heat the metal absorbed/released and q soln absorbed/released. C is (q cal / delta T). 

m water - 100 g

m metal - 5.332 g

cp water - 4.184

cp metal - n/a

delta t water - 5.5

delta t metal - 23.5

I heated up the water and kept the metal at room temperature, so I think I would switch up the equation so that it goes like this: 

q soln = -(q rxn + (C * delta T)... first of all, is that right? In addition, because the specific heat of the metal (rxn) is unknown, i replaced it with the variable X. So broken up it would look like this: 

m water * cp water * delta T water = -((m metal * X * delta T metal) + (C * delta T)).... But if I use a variable in the equation, then according to basic algebra I would distribute the negative to the q and C * T making them both negative. After, I would add C * T to the q soln which would be negative, giving me a positive value. In the end, my X or specific heat of the metal would equate to -6.6, which is very inaccurate given that most specific heats are below 1 J/g * C. 

How can I fix my calculations? 

Edited by kwona

Archived

This topic is now archived and is closed to further replies.

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.

Configure browser push notifications

Chrome (Android)
  1. Tap the lock icon next to the address bar.
  2. Tap Permissions → Notifications.
  3. Adjust your preference.
Chrome (Desktop)
  1. Click the padlock icon in the address bar.
  2. Select Site settings.
  3. Find Notifications and adjust your preference.