[helpmehelp]

1. Calculate the heat of capacity of the calorimeter if 50 ml of water at 32°C was mixed with 50.0 ml water at 56 °C. The equilibrium temperature after mixing is 25°C.

2. Determine the mass of NaNO3 (electrolye) needed so that the boiling point of an aqueous solution of NaNO3 will be 4.5°C higher than that of pure water.
Kb of water = 0.512 °C/m.
Assume mass of pure water used is 1.0 kg.Molar Mass = 84.9947 g/mol

3. 11.0 g of NaOH (40 g/mol) is added to 100 g of water in a coffee cup calorimeter. The temperature was observed to increase from 25.7°C to 35.4°C. The heat capacity of the calorimeter is 21.51 J/°C. Calculate the heat of the reaction. (Specific heat of water: 4.184 J/g°C)

4. Calculate the Molar mass of 2,172.00 mg unknown solute which is used to prepare 2.162M solution dissolved in 450 ml of water.

5. Calculate the freezing point of 67,215 mg of glucose (C₆H₁₂O₆) which is non-electrolyte in 1.5617 L of water (H2O).
Kf = 1.86 °C/m
molar mass of glucose = 180.156 g/mol
molar mass of water = 18.016 g/mol

6. Carbonic acid is an example of weak acid. Calculate the Ka of carbonic acid (H2CO3) based on the following information here:
Initial concentration of H2CO3 = 5.555 x 10^-3 M
Equilibrium concentration of H2CO3 = 5.50 x 10^-3 M

7. Calculate the pH of 0.3659 M of unknown WEAK base which has a Kb of 1.41X10^-6.

8. Calculate the pH of 0.4132 M of unknown acid which has a Ka of 3.51X10^-5

My answers:

1. 7949.6 J/°C

2. 186.76 g

3. -4267.18 J

4. 2.23 g/mol

5. 100.44 °C

6. 4.4x10^-7

7. 10.86

8. 2.42

[sjb]

Without seeing your working - this might be difficult, but some answers do stand out - for instance 5 - does water usually freeze at 100°C?