Question

 

Part 1: A pot is made of 500 g steel with specific heat of 0.10 cal/(g °C). How much heat is needed to raise its temperature from 30 °C to 100 °C?

Part 2: If we add 500 g of water into the pot above, how much heat is needed to raise the temperature of the pot of water from 30 °C to 100 °C?

2. A balloon shrinked to 90% of its orginal size after it was taken out of a 27 °C room. Determine the temperature outside.

3. Circle one per line:

When (temperature/pressure/volume) rises, the water molecules have high enough (thermal/potential/chemical) energy to overcome the (covalent/ionic/attractions) between the water molecules in the liquid phase and enter the (gas/liquid/solid) phase.

4. How many moles of ions will one mole of K3PO4 dissociate into when it dissolves in water?

A) 0

B) 1

C) 2

D) 3

Answer 1

part 1

heat required(q) = m*s*DT

                  = 500*0.1*(100-30)

                  = 3500 cal

                  = 3.5 kcal

part2

heat required(q) = mass of metal*smetal*DT+ mass of water*Swater*DT

                  = 500*0.1*(100-30) + 500*1*(100-30)

                  = 38.5 kcal

2) from charles law

    V1/T1 = V2/T2

let us assume, initial volume(V1) = 1 L , T1 = 27 c = 300.15 k

                final volume(V2) = 0.9 L , T2 = ?

(1/300.15) = (0.9/T2)

T2 = final temperature = 270.135 k

3) Temperature , Thermal , attractions , gas

4) 1 mole K3PO4 = 1 mol PO4^3- + 3 mol K+ ions,

               Total 4 mol ions.

answer not given