Hydrogen Sulphide Research Paper

Hydrogen sulphide has a boiling point of -82 degrees Celsius and a melting point of -60 degrees Celsius. There are 2 hydrogen and 1 sulphide molecule. Simple molecule’s which are covalent have lower melting and boiling points as they do not need too much energy to separate the bonds because they are as polarised as water. In hydrogen sulphide the intermolecular forces are known as Dipole-Dipole forces which are less powerful than hydrogen bonding which is in water therefore water has the strongest bond compared to hydrogen chloride and hydrogen sulphide. Water is more electronegative than hydrogen chloride and hydrogen sulphide because there are more molecules in water which are drawn together however in hydrogen sulphide there are less molecules

which are drawn together. The bonding in hydrogen sulphide is known as covalent bonding because these bonds are stronger then the bonds in hydrogen chloride. Hydrogen sulphide has Dipole- Dipole forces (but they are temporary which means that hydrogen sulphide is not soluble) which are a type of intermolecular force. Hydrogen Sulphide cannot be mixed enough for it to dissolve because it does not ionise therefore the opposite ends of the polar molecules in the hydrogen sulphide cannot become attracted to each other as ionisation has to happen so that the molecules can be drawn together.

The molecule hydrogen sulphide contains one sulphide atom however it is less electronegative than oxygen which is found in a water molecule therefore in hydrogen sulphide there are not hydrogen which are connected to any very powerful electronegative molecules for example oxygen, nitrogen and fluorine. However in hydrogen sulphide there are lone pairs of electrons which may be used to make a bind which is known as hydrogen bonds.

Uncontaminated water has a pH value of 7. This means that it is neutral as there is a scale to calculate the acidity or alkalinity of a substance. The scale is from 0-14. Hydrochloric acid is 0 which means it is strongly acidic therefore it is dangerous and corrosive which means that it can burn the skin if you do not wear gloves. Hydrogen sulphide has a pH value of 4.1 this means that it is acidic as any value below 7 is acidic however it is a weak acid therefore it is not corrosive but it is toxic and harmful to the environment. The pH is important as this enables us to be safe and the hydrogen molecules present in a substance can affect how strong

the bonds are. Intermolecular forces are important because if a substance is polar then that means it is soluble therefore water is a solvent because substances dissolve in water like salt. For example the intermolecular forces between the water and the salt should be very high even higher than the forces which draw molecules together inside the solute and the solvent. Weak intermolecular forces means that the bond will easily break this means that the solubility will be low but if the intermolecular forces are strong then it will ages for the molecule to break so that means that it will be very soluble. Therefore more energy will be needed to break the bond, molecular size affects how fast the bonds are broken because you need a lot of energy therefore a longer chain of molecules requires more energy. That is why more energy is released when smaller chains break because the smaller a chain is the less friction there is this friction also known as resistance prevents the longer chain molecules from breaking apart therefore more energy is needed so that the longer chain of molecule can break apart and this is the reason why small insects do not drown in a small drop of water because of waters unique properties such as it has a high polarity. If the electronegativity of a molecule is high then the atom is more attracted to other electrons in a molecule.

Negative ions are created when atoms have a high electronegative charge when they are bonded by covalent bonds to atoms which have a smaller electronegative charge share more electrons compared to the other atom. That is why a tiny negative charge on the atom; is more electronegative and a tiny positive charge which is on the atom ( that it is connected to the molecule) this bond is called a polar covalent bond. The elements electronegativity rises from the top of the groups in the periodic table and from the left to the right across the period in the periodic table. Hydrogen is an atom however it is not as electronegative as oxygen because hydrogen has an electronegativity value of 2.0 on the Pauling scale but oxygen has an electronegativity value of 3. 5 therefore the difference between these two values is 3.5 -2=1.5 which means that the difference in the electronegativity value for hydrogen and oxygen is 1.5. This difference is the reason why water is a polar molecule specifically a polar covalent molecule. The electronegativity value for sulphur is 2.58 on the Pauling scale of electronegativity this suggest that sulphur is also an electronegative molecule Chloride has an electronegativity value of

3.16 on the Pauling scale of electronegativity. In hydrogen chloride the chloride because the difference between the electronegativity value of chloride and sulphur is 3.16 -2.58= 0.58 therefore the difference is not a lot compared to the difference between hydrogen and oxygen. Fluorine is the most electronegative molecule because its electronegative value is 3.98 which is 0.02 off the number 1.00. Electronegativity is a word which means that the atom has the potential to attract electrons which are in the form of a bond. Therefore, this word decides what kind of bond is formed in between two atoms. The higher the electronegativity value the more the atom attracts the electrons therefore it is a very powerful atom but the molecule is known as very electronegative because then that means that the atom has attracted more electrons which are found in a bond. The periodic table is a table of all of the elements which scientists have found over the centuries furthermore when you go up and to the right hand side of the periodic table the electronegativity difference between two atoms which are bonded to each other is measured so that the kind of bond present in that molecule is found. Electronegativity difference values which are in between 3.3-1.7 means that the bond is ionic, if the differences are 0-1.7 then the bond is a covalent bond and if the electronegativity difference vale is between 0-0.5 then it is known as a non-polar covalent bond. Covalent bonds are made when the electronegativity difference value is from 0.5-1.7. The solubility of compounds is based on two things they are the size of the molecules and the value of the molecules electronegativity. Therefore if the difference in the electronegativity is big then the dipole-dipole forces become permanent. Therefore they become more soluble because of the attraction forming between the positive and negative molecules. Therefore the bigger the molecule the less soluble it is because there is less chance of hydrogen bonds to be form. Longer molecules are also less soluble because they need a lot of energy to separate the bonds therefore smaller molecules break more quickly as they do not need a lot of energy. The surface area of the particles which are solutes for example salt and water can affect the solubility because it decides if the molecule will dissolve quickly or it may take ages for the solute to dissolve. If the total surface area of the salt molecules have a larger value then the salt will dissolve faster but when a molecule has a smaller chain of molecules then this makes it surface area bigger so therefore the solubility will be very high. Therefore smaller molecules are more soluble than bigger molecules. Intermolecular forces affect solubility because these forces draw molecules which are solute and the solvent which is usually water as water is a universal solvent for example salt is a common example of a solute which can be added to water. The solute- solvent forces have to make sure that they can control the attractions which are found in between the solute-solute and the solvent-solvent. If the solute-solvent attraction is weak than the solute-solute and solute-solvent attractions, then the solute will not dissolve a lot.