Molar Heat of Combustion of Alkanols (Hsc Chem)
Molar Heat of Combustion
Aim:
To find the molar heat of combustion for four different alkanols:
1. Methanol
2. Ethanol
3. 1-Propanol
4. 1-Butanol
- And to compare the experimental value with the theoretical.
Background:
The Molar Heat of Combustion of a substance is the heat liberated when 1 mole of the substance undergoes complete combustion with oxygen at standard atmospheric pressure, with the final products being carbon dioxide gas and liquid water. (Ref. “Conquering Chemistry, Roland Smith, 2005”)
The Heat Capacity of a substance is the amount of heat energy it must consume in order to raise its temperature by 1 Kelvin or 1° Celsius. The heat capacity of 1 mol of a pure substance is known as its molar heat capacity, which can be expressed in J K-1 g-1. The heat capacity of 1 gram of a substance is known as its specific heat, which can also be expressed in J g-1 K-1.
Specific Heat Capacities of:
Water – 4.18 J g-1 K-1
Copper – 0.385 J g-1 K-1
The equation below relates the specific heat of a substance, the temperature change, and the mass of the substance and how much energy was put into the system. q = mCΔT
Where:
q = quantity of heat (joules) m = Mass (grams)
C = specific heat capacity J g-1 K-1
ΔT = change in temperature (final – initial) (K or °C)
Hypothesis:
It is hypothesised that as the number of carbon chains in each alkanol increases, the energy required to raise the temperature of the water will also increase.
Variables:
• Independent o Type of alkanol used; Methanol, Ethanol, 1-Propanol, 1-Butanol.
• Dependent o Mass of spirit burner. o Maximum Temperature of water reached. (This is the maximum temperature in which the water reaches after it has risen 20°C and the spirit burner put out). o Energy released per mole of the fuel burnt.
• Controlled o Change in temperature of water; 20°C rise in temperature.
Apparatus:
• Goggles
• Bench mat
• Retort stand
• Boss head x 2
• Clamp x 2
• Thermometer
Aim:
To find the molar heat of combustion for four different alkanols:
1. Methanol
2. Ethanol
3. 1-Propanol
4. 1-Butanol
- And to compare the experimental value with the theoretical.
Background:
The Molar Heat of Combustion of a substance is the heat liberated when 1 mole of the substance undergoes complete combustion with oxygen at standard atmospheric pressure, with the final products being carbon dioxide gas and liquid water. (Ref. “Conquering Chemistry, Roland Smith, 2005”)
The Heat Capacity of a substance is the amount of heat energy it must consume in order to raise its temperature by 1 Kelvin or 1° Celsius. The heat capacity of 1 mol of a pure substance is known as its molar heat capacity, which can be expressed in J K-1 g-1. The heat capacity of 1 gram of a substance is known as its specific heat, which can also be expressed in J g-1 K-1.
Specific Heat Capacities of:
Water – 4.18 J g-1 K-1
Copper – 0.385 J g-1 K-1
The equation below relates the specific heat of a substance, the temperature change, and the mass of the substance and how much energy was put into the system. q = mCΔT
Where:
q = quantity of heat (joules) m = Mass (grams)
C = specific heat capacity J g-1 K-1
ΔT = change in temperature (final – initial) (K or °C)
Hypothesis:
It is hypothesised that as the number of carbon chains in each alkanol increases, the energy required to raise the temperature of the water will also increase.
Variables:
• Independent o Type of alkanol used; Methanol, Ethanol, 1-Propanol, 1-Butanol.
• Dependent o Mass of spirit burner. o Maximum Temperature of water reached. (This is the maximum temperature in which the water reaches after it has risen 20°C and the spirit burner put out). o Energy released per mole of the fuel burnt.
• Controlled o Change in temperature of water; 20°C rise in temperature.
Apparatus:
• Goggles
• Bench mat
• Retort stand
• Boss head x 2
• Clamp x 2
• Thermometer