Topic: Determining the enthalpy change for different chemical reactions.
I familiarised myself with the Material Safety Data Sheets of toxic substances.
PLANNING (A)
Enthalpy (H)1 - The sum of the internal energy of the system plus the product of the pressure of the gas in the system and its volume:
Esys is the amount of internal energy, while P and V are respectively pressure and volume of the system.
However, to make it simpler, this definition can be shortened. Enthalpy (H) is a measure of heat in the system.
To measure the enthalpy we have to first figure out the mass of a substance under a constant pressure and determine the internal energy of the system.
The enthalpy change (H)2 is the amount of heat released or absorbed when a chemical reaction occurs at constant pressure.
Standard conditions3 are used in order to allow experiments that are taken at different locations to come out with the same results. Standard pressure is 1 atmosphere or 1.0135 x 105 pascals. Standard temperature is 25o C. Standard state is the physical state at which an element or a compound exists at standard conditions.
Hypothesis: If the temperature of a given substance is known, we may calculate the enthalpy of this substance.
Experiment I Part I
PLANNING (B)
Requirements:
- 1 beaker [250 cm3]
- 2 test tubes
- thermometer
- 60 cm -3 of 2 mol dm-3 hydrochloric acid
- solid anhydrous sodium carbonate (Na2CO3) [3.75 g]
- balance
Procedure:
We were provided with 2 mol dm-3 hydrochloric acid, solid sodium hydrogencarbonate and solid anhydrous sodium carbonate.
. One person in each pair measured 30 cm3 of approximately of 2 mol dm-3 hydrochloric acid into the beaker.
2. We took the temperature of the acid and recorded it in table 1.
3. We weighted a test tube empty and than again when it contained 2.80 g of anhydrous sodium carbonate.
4. We recorded the masses in a table similar to table 1.
5. Subsequently we added the weighted portion of Na2CO3 to the acid and stirred the mixture carefully with the thermometer until all the solid has reacted.
6. While mixing we recorded the maximum temperature of the solution.
DATA COLLECTION
2HCl (aq) + Na2CO3 (s)› 2NaCl (aq) + CO2 (g) + H2O (l)
I familiarised myself with the Material Safety Data Sheets of toxic substances.
PLANNING (A)
Enthalpy (H)1 - The sum of the internal energy of the system plus the product of the pressure of the gas in the system and its volume:
Esys is the amount of internal energy, while P and V are respectively pressure and volume of the system.
However, to make it simpler, this definition can be shortened. Enthalpy (H) is a measure of heat in the system.
To measure the enthalpy we have to first figure out the mass of a substance under a constant pressure and determine the internal energy of the system.
The enthalpy change (H)2 is the amount of heat released or absorbed when a chemical reaction occurs at constant pressure.
Standard conditions3 are used in order to allow experiments that are taken at different locations to come out with the same results. Standard pressure is 1 atmosphere or 1.0135 x 105 pascals. Standard temperature is 25o C. Standard state is the physical state at which an element or a compound exists at standard conditions.
Hypothesis: If the temperature of a given substance is known, we may calculate the enthalpy of this substance.
Experiment I Part I
PLANNING (B)
Requirements:
- 1 beaker [250 cm3]
- 2 test tubes
- thermometer
- 60 cm -3 of 2 mol dm-3 hydrochloric acid
- solid anhydrous sodium carbonate (Na2CO3) [3.75 g]
- balance
Procedure:
We were provided with 2 mol dm-3 hydrochloric acid, solid sodium hydrogencarbonate and solid anhydrous sodium carbonate.
. One person in each pair measured 30 cm3 of approximately of 2 mol dm-3 hydrochloric acid into the beaker.
2. We took the temperature of the acid and recorded it in table 1.
3. We weighted a test tube empty and than again when it contained 2.80 g of anhydrous sodium carbonate.
4. We recorded the masses in a table similar to table 1.
5. Subsequently we added the weighted portion of Na2CO3 to the acid and stirred the mixture carefully with the thermometer until all the solid has reacted.
6. While mixing we recorded the maximum temperature of the solution.
DATA COLLECTION
2HCl (aq) + Na2CO3 (s)› 2NaCl (aq) + CO2 (g) + H2O (l)
