[Azureilai]

Can someone please show me the set up to these four problems? I kind of know how to do it with dimensional analysis, but I got it wrong, so i need help on where the numbers go and why. I know it is an unusually long post and I apologize but I actually attempted at it and still got it wrong on my test so I would like help knowing why. Thank you everyone. (my workouts for each questions are listed at the bottom)

1. What mass of zinc is required if 3125 joules of zinc is needed to increase the temperature of zinc from 22 degree C. to 67.3 degree C?
(Specific Heat of zinc = 0.39(kJ/kg K), or 0.093(kcal/kgoC), or 0.09(Btu/lbmoF) (I have no idea which one to use so I'm just going to provide all the specific heats given to me on the formula sheet.)

2. The specific heat of silver is 0.237 J/gram*degree C. If 125.0g Ag at 100 degree C. is placed in 250.0 g of water at 25 degree C, what is the final temperature?

3. 225 g of metal at 275 degree C. is placed into a styrofoam cup containing 185 mL of water at 30 degrees C. What is the final temperature of the metal?

4. How many joules are required to change 9.0g of water at 30 degree C. to steam at 110 degree C.?

For the first question, I made the equation 3125J*Tf-22(degree C) = 3125 j * Tf + 67.3(degree C). But thats as far as I got, because i didn't know where to put the specific heat for zinc.

Second question : 0.237J*125g*Tf-100(degree C) + 4.184J*250g*Tf+25(degree C) = 0

Third: 2.45*225g*Tf-275(degree C) + 4.124J*185*Tf+30(degree C) = 0

Fouth: $.184*9*(100-30)(degree C) = ? J*9 g*(110+80)(degree C)

Can anyone tell me what I did wrong? Because I don't actually know how to do this so I was guessing.

[Borek]

In general

Q = m c ΔT

ΔT = T_final - T_initial

and

Q_lost = Q_gained

Does it help?

To do the first question you need just a first and second of these equations. Can you write what is Q and what is ΔT for this problem?

[Azureilai]

Yes it helped. Thank you. I googled the formula and plugged in the number and was able to solve for number one, getting 0.1769 kg. My friend helped me with the other problems with that equation so I got the right answer (finally). The equation cleared up some confusion I had since my class was teaching us how to use dimensional analysis to solve for the specific heat instead and I was confused.