2. ∆T is positive when T increases, and q is positive
1)Calculate ∆T for 4.0 gram water absorbing 33 J.
q = mC∆T
33 J = 4.0g * J * ∆T oC
goC
∆T = 2.02…choice 2
∆T is positive when T increases, and q is positive
2) Calculate T2 for 2.0 grams of water at 15oC absorbing 84 J.
q = mC(T2 – T1)
84 J = 2.0 g * 4.18 J/ g oC (T2 - 15oC)
T2 = 25oC

3. 3) 50. grams of water is heated, temp increases to 50 oC and 4,180 J of heat is added. What is initial temp?
q = mC∆T, q=mC(T2 – T1)
4180 = 50 g * 4.18 oC/g * ( 50 oC – T1 )
T1= 30 oC
4) 7.00 grams of water is heated, temp increases from 10.0 to 15.0 oC how much energy is absorbed?
q = mC∆T, q=mC(T2 – T1)
q = 7.00 g * 4.18 oC/g * ( 15 oC – 10oC )
q= 146 J

4. 5) Calculate J absorbed by 200. 0 g when the temp increases form 10
5) Calculate J absorbed by g when the temp increases form 10.0 to 40.0 oC.
q = mC∆T
q = 200.0g * * ( )
q = 200.0g * * (30 oC) = 25,080 J
6) Find kJ of heat absorbed when g water is vaporized at its boiling pt.
q = mHvap
q = 70.0g * J/g = J / 1000 = kJ

5. 7) How many grams of water absorb 2510 J of energy when the temp changes from 10 to 30 oC.
q = mC∆T
2510J = X g * J * 20oC = grams water
10) The temp of 50g of water is raised to 50 oC be the addition of 1000 cal of energy, find initial temp (T1).
q = mC∆T
1000 = 50g * 1.0 cal g * (50 - T1)
T1 = 30