Procedure

a) Determination of the heat capacity:

1. Add 9.6 ± 0.1 ml of hydrofluoric acid and 388.0 ± 0.1 ml of 2.0 N nitric acid in the calorimeter at a temperature of 27 ± 2°C.

2. Take some amount of Zinc oxide adequate for six deductions. Heat about 7 g of zinc oxide to 900-950°C for each determination and then cool it for not less than 2 hours and not more than 5 hours in a desiccator, having anhydrous calcium chloride.

3. It is then ground to pass a 150 μm IS sieve.

4. Set up the calorimeter, and run the stirrer for 5 min to attain a constant temperature. Note down the readings every minute for 5 minutes for initial heating or cooling correction.

5. Add ZnO gradually from the funnel which is cleaned with a camel hair brush, throughout 1-2min. Record the temperature at one-minute intervals until the solution is complete. The duration of the solution shall not be more than 20 minutes.

6. Proceed for additional 5 minutes to obtain the final heating or cooling correction.

7. The graph is plotted between the initial and final heating or cooling rates and the corresponding calorimeter temperature, called the Beckmann readings. The corrections are then observed for each reading.

Compute the heat capacity ( in J/°C) as follows:-

where- Φ = final temperature of the calorimeter in °C , Φ. = room temperature in °C

b) Preparation of cement sample:

1. Take 60 g of cement and 24 ml of distilled water and mix it for about 4 minutes.

2. Add this mixture inside three glass/plastic vials, and cork. Seal it with wax and then store it in a vertical position at 27 ± 2°C.

c) Determination of the heat of solution:

1. Take about 3 g of unhydrated cement sample to determine the heat of solution and an additional 7 g of the sample for ignition loss. Perform the procedure for temperature- rise as done for ZnO.

2. Calculate the heat of solution (in kJ/kg) of unhydrated cement: -

where 0.8 is the specific heat of unhydrated cement

3. Find the mean of three readings that are calculated within 7 days of mixing of hydrated samples.

4. Now, open one of the glass vials and grind the cement to pass an 850-micron sieve. Pour this ground sample in a stoppered bottle and then take out about 4.2 g of sample for heat of solution and 7 g of sample for loss on ignition.