CALORIMETRY And Use of calorimetry with problems

Quick lesson of Calorimetry

1. CALORIMETRY

2. WHAT IS CALORIMETRY? Calorimetry is the process of measuring the amount of heat released or absorbed during a chemical reaction. By knowing the change in heat, it can be determined whether or not a reaction is exothermic (releases heat) or endothermic (absorbs heat). Calorimetry measures enthalpy changes during chemical processes.

3. CALORIMETER Bomb calorimeter

4. Formula for calculating the amount of heat transferred Where: q – amount of heat absorbed or evolved in joule or calorie c – the specific heat of water since the solution is fairly dilute (c = 4.18 J/g-°C or c = 1 cal /g-°C) m – the mass of solution in grams (essentially mass of water) Δ𝑡 – the change in temperature (t 1 – t 2 ) in °C    

5. =   reaction   Molar Heat of Reaction   no. of moles, n

6. SAMPLE PROBLEM #1 A student mixes 25 mL of 0.1M HCl and 25 mL of 0.1M KOH in a calorimeter. Upon complete mixing, the temperature of the resulting solution changes from 25°C to 32.5°C. Calculate the molar heat of reaction or neutralization, Δ𝐻 .

7. SAMPLE PROBLEM #2 3.36g of ethanol (C 2 H 5 OH) is burnt in a bomb calorimetry with a heat capacity of 2.3 kJ/C. The temperature of the calorimeter increases from 12.1C to 55.5C. Calculate the energy of combustion per mole

8. SAMPLE PROBLEM #2 3.36g of ethanol (C 2 H 5 OH) is burnt in a bomb calorimetry with a heat capacity of 2.3 kJ/C. The temperature of the calorimeter increases from 12.1C to 55.5C. Calculate the energy of combustion per mole.

9. SAMPLE PROBLEM #3 A student dissolves 10.0 g NaOH in 100 ml of water in a calorimeter at 24.5°C. As the NaOH dissolves, the temperature of the surrounding water rises to 33.0°C. Determine the heat of solution of NaOH in J/g.

10. SAMPLE PROBLEM #4 A 1.000 g sample of octane (C 8 H 18 ) is burned in a bomb calorimeter containing 1200 grams of water at an initial temperature of 25.00ºC. After the reaction, the final temperature of the water is 33.20ºC. The heat capacity of the calorimeter is 837 J/ºC. The specific heat of water is 4.184 J/g ºC. Calculate the heat of combustion of octane in kJ/mol.