Energy profile of exothermic reaction Energy profile of endothermic reaction A)Doc Brown (2016) B)Doc Brown (2016)
Thermodynamic reactions occur when there is a difference of energy during a chemical reaction.
There are two types;
Firstly, Exothermic reactions; This is when the initial reactants use less energy to break their existing bonds, than what energy was required to make the new bonds. The extra heat is spreads out into the surroundings (see above diagram A)
An experiment was carried out using copper (II) sulphate and magnesium powder.
Mg + CuSO4 MgSO4 + Cu
The temperature of the copper (II) sulphate at the start of the experiment was 18°c, magnesium powder was stirred into the solution. It was found that …show more content…
What are the two major sources of error in this experiment?
In the experiment we used a copper can; Heat energy is able to escape through the can making the exact results inaccurate, the copper can could be insulated and would give more accurate results.
Also heat from the flame could be lost in the surrounding atmosphere as during the experiment the flame was exposed, a combustion calimeter would also give more accurate results.
4. What two factors would you consider when choosing an alcohol as a fuel?
While burning alcohol a lot of carbon monoxide is released as it burns; consideration would need to be made about pollution. If a lot of carbon monoxide is released it would make the fuel less efficient.
The overall cost would need to be taken into consideration. The heat it gives out vs. the cost per litre; would still be expensive even if methanol the cheapest (per litre) was chosen as its uses a lot more energy so wouldn’t necessarily be cost effective (Gallagher and Ingram, 2000)
5. Use the table to calculate the molar mass of each alcohol. (Relative atomic masses: H = 1, C = 12, O = 16).
Alcohol Formula
Methanol CH3OH
Ethanol C2H5OH
Propanol C3H7OH
Butanol …show more content…
Whilst looking at a substances fixed temperature, you need to consider the properties, such as structure, molecular size and the intermolecular force.
Below are a few examples
Covalent
A covalent bond is between two non-metallic atoms. These are held in a simple molecular lattice with individual molecules (see diagram A below of an Iodine molecule) with a strong covalent bond. A) s-cool (2016)
The melting and boiling points are quick low and can be broken with relatively little energy (OCR, 2008), the low melting and boiling points are due to the fact you only need to overcome the weak intermolecular force, not the covalent bond.
A covalent bond has electrostatic forces of attraction between shared pairs of electrons, another example is of a giant covalent bond.
A giant covalent bond is held in a giant molecular lattice structure. (See diagram B below.)
B) s-cool (2016)
This giant structure is made of strong covalent bonds, so to break these bonds it takes a lot of energy,(OCR 2008) this results in the melting and boiling points of a giant covalent bond being extremely high to overcome the strong electrostatic force between the electrons.
Thermodynamic reactions occur when there is a difference of energy during a chemical reaction.
There are two types;
Firstly, Exothermic reactions; This is when the initial reactants use less energy to break their existing bonds, than what energy was required to make the new bonds. The extra heat is spreads out into the surroundings (see above diagram A)
An experiment was carried out using copper (II) sulphate and magnesium powder.
Mg + CuSO4 MgSO4 + Cu
The temperature of the copper (II) sulphate at the start of the experiment was 18°c, magnesium powder was stirred into the solution. It was found that …show more content…
What are the two major sources of error in this experiment?
In the experiment we used a copper can; Heat energy is able to escape through the can making the exact results inaccurate, the copper can could be insulated and would give more accurate results.
Also heat from the flame could be lost in the surrounding atmosphere as during the experiment the flame was exposed, a combustion calimeter would also give more accurate results.
4. What two factors would you consider when choosing an alcohol as a fuel?
While burning alcohol a lot of carbon monoxide is released as it burns; consideration would need to be made about pollution. If a lot of carbon monoxide is released it would make the fuel less efficient.
The overall cost would need to be taken into consideration. The heat it gives out vs. the cost per litre; would still be expensive even if methanol the cheapest (per litre) was chosen as its uses a lot more energy so wouldn’t necessarily be cost effective (Gallagher and Ingram, 2000)
5. Use the table to calculate the molar mass of each alcohol. (Relative atomic masses: H = 1, C = 12, O = 16).
Alcohol Formula
Methanol CH3OH
Ethanol C2H5OH
Propanol C3H7OH
Butanol …show more content…
Whilst looking at a substances fixed temperature, you need to consider the properties, such as structure, molecular size and the intermolecular force.
Below are a few examples
Covalent
A covalent bond is between two non-metallic atoms. These are held in a simple molecular lattice with individual molecules (see diagram A below of an Iodine molecule) with a strong covalent bond. A) s-cool (2016)
The melting and boiling points are quick low and can be broken with relatively little energy (OCR, 2008), the low melting and boiling points are due to the fact you only need to overcome the weak intermolecular force, not the covalent bond.
A covalent bond has electrostatic forces of attraction between shared pairs of electrons, another example is of a giant covalent bond.
A giant covalent bond is held in a giant molecular lattice structure. (See diagram B below.)
B) s-cool (2016)
This giant structure is made of strong covalent bonds, so to break these bonds it takes a lot of energy,(OCR 2008) this results in the melting and boiling points of a giant covalent bond being extremely high to overcome the strong electrostatic force between the electrons.