Nt1310 Unit 2 Lab Report
OCR B (Salters) AS level Chemistry
UNIT 2 – F332
Elements from the sea
Halogens and Halides (group 7 chemistry)
* Halogen is the elemental molecule, eg/ Cl₂, Br₂ * Halide is in a compound, eg/ KBr, KCl
| Fluorine | Chlorine | Bromine | Iodine | Appearance at room temp | Pale yellow gas | Green gas | Dark red volatile liquid | Shiny black solid – sublimes to purple gas |
Halide | Colour precipitate with silver nitrate | KCl | White | KBr | Cream | KI | Pale Yellow |
Redox reactions
‘Reduction is gain of electrons, oxidation is loss of electrons’
Examples;
Overall reaction = 2KBr + Cl₂ 2KCl + Br₂
Halogens get more reactive going up the group, and in redox reactions the less reactive element …show more content…
Such a bond is said to be polar. A polar bond results in the unequal sharing of the electrons in the bond’
Types of intermolecular bonds * Instantaneous - Induced dipole (IDID) < 10KJ/mol * Permanent dipole - Permanent dipole (PDPD) 10-20KJ/mol * Hydrogen bonding 10-40KJ/mol
Instantaneous – Induced dipoles (can occur in ALL molecules) * Occurs when more of the electrons happen to be at one end than the other, so one end is slightly (delta) negative and the other slightly (delta) positive. * Can cause induced dipoles if near other molecules. * Permanent dipoles can also induce dipoles if near other molecules. * Larger molecules have more electrons so strength of IDID is …show more content…
* The small H atom has to be able to get very close to the F, O or N atoms in adjacent molecules. * A lone pair of electrons in adjacent F, O or N atom, which positively charged H atom can line up with. * A special case of PDPD. * Strongest type of intermolecular bond.
(Happens a lot in alcohol group. More O-H = more hydrogen bonds.)
More hydrogen bonds means a higher boiling point as these bonds are quite strong and need to be broken before the molecule can become a gas.
Electronegativity is the ability of an element to draw electrons to itself.
Purification of an organic liquid product 1. Shake with sodium hydrogencarbonate to remove acidic impurities. 2. Separate from other immiscible liquids using a separating funnel. 3. Dry with anhydrous sodium sulphate. 4. Simple distillation to collect pure product
Nucleophillic substitution ‘A nucleophile is a species which is strongly attracted to a region of positive charge in another molecule, and can donate an electron pair’ SN2
UNIT 2 – F332
Elements from the sea
Halogens and Halides (group 7 chemistry)
* Halogen is the elemental molecule, eg/ Cl₂, Br₂ * Halide is in a compound, eg/ KBr, KCl
| Fluorine | Chlorine | Bromine | Iodine | Appearance at room temp | Pale yellow gas | Green gas | Dark red volatile liquid | Shiny black solid – sublimes to purple gas |
Halide | Colour precipitate with silver nitrate | KCl | White | KBr | Cream | KI | Pale Yellow |
Redox reactions
‘Reduction is gain of electrons, oxidation is loss of electrons’
Examples;
Overall reaction = 2KBr + Cl₂ 2KCl + Br₂
Halogens get more reactive going up the group, and in redox reactions the less reactive element …show more content…
Such a bond is said to be polar. A polar bond results in the unequal sharing of the electrons in the bond’
Types of intermolecular bonds * Instantaneous - Induced dipole (IDID) < 10KJ/mol * Permanent dipole - Permanent dipole (PDPD) 10-20KJ/mol * Hydrogen bonding 10-40KJ/mol
Instantaneous – Induced dipoles (can occur in ALL molecules) * Occurs when more of the electrons happen to be at one end than the other, so one end is slightly (delta) negative and the other slightly (delta) positive. * Can cause induced dipoles if near other molecules. * Permanent dipoles can also induce dipoles if near other molecules. * Larger molecules have more electrons so strength of IDID is …show more content…
* The small H atom has to be able to get very close to the F, O or N atoms in adjacent molecules. * A lone pair of electrons in adjacent F, O or N atom, which positively charged H atom can line up with. * A special case of PDPD. * Strongest type of intermolecular bond.
(Happens a lot in alcohol group. More O-H = more hydrogen bonds.)
More hydrogen bonds means a higher boiling point as these bonds are quite strong and need to be broken before the molecule can become a gas.
Electronegativity is the ability of an element to draw electrons to itself.
Purification of an organic liquid product 1. Shake with sodium hydrogencarbonate to remove acidic impurities. 2. Separate from other immiscible liquids using a separating funnel. 3. Dry with anhydrous sodium sulphate. 4. Simple distillation to collect pure product
Nucleophillic substitution ‘A nucleophile is a species which is strongly attracted to a region of positive charge in another molecule, and can donate an electron pair’ SN2