EX3: BOILING & MELTING POINT Flashcards
- the temperature at which the VAPOUR PRESSURE of the substance is EQUAL to the ATMOSPHERIC PRESSURE above it
BOILING POINT
a liquid at a higher pressure has a _____ boiling point than a liquid at a lower atmospheric pressure
HIGHER
BOILING POINT is also an indicator of the ___ of the compound
VOLATILITY
what is the volatility of low boiling point
HIGH VOLATILE
- at a given temperature, a compound will exist as _____ if it has a LOW NORMAL BOILING POINT
GAS
- at a given temperature, a compound will exist as ______ if it has HIGHER NORMAL BOILING POINT
LIQUID OR SOLID
- it occurs between one molecule and another, influences directly the boiling point and are dependent on the functional groups present on the organic compound
INTERMOLECULAR FORCES OF ATTRACTION
WITHIN THE MOLECULE
INTRA
BETWEEN MULTIPLE MOLECULES
INTER
- WEAK INTERMOLECULAR ATTRACTION formed by induced polarization of molecules which is caused by FLUCTUATING CHARGES due to the NEARNESS OF THE MOLECULES as they vibrate
VAN DER WAALS DISPERSION FORCES
VAN DER WAALS DISPERSION FORCES is commonly observed among ____
HYDROCARBON GROUPS
VAN DER WAALS DISPERSION FORCES occurs only within _____ between molecules
SHORT DISTANCES
- occurs among PARTIALLY IONIC or polar molecules
- these molecules contain an ASYMMETRICAL CHARGE due to the two poles of the molecule: one end is partially negative while the other end is partially positive
DIPOLE-DIPOLE INTERACTION
DIPOLE-DIPOLE INTERACTION occurs among ____
PARTIALLY IONIC / POLAR MOLECULES
- formed between PARTIALLY POSITIVE (H+) and an ADJACENT ELECTRONEGATIVE ATOM which bears a partial negative charge
- intermolecular hydrogen bonds tend to rise boiling point of an organic compound
basta may Hydrogen + electronegative atom**
HYDROGEN BONDING
- intermolecular hydrogen bonds tend to ____ boiling point of an organic compound
RISE
- takes place between molecules having OPPOSITE CHARGES and INVOLVES AN ELECTROSTATIC INTERACTION between the two opposite charges
- the functional groups which most easily ionize are AMINES and CARBOXYLIC ACIDS, such as the reaction of ammonia (NH3 with a carboxylic acid (carboxylate ion)
IONIC BONDING
in IONIC BONDING, the functional groups which most easily ionize are _____ and ______
AMINES AND CARBOXYLIC ACID
amino acid is acidic or basic
NEUTRAL bcos amino = base & acid = acid, hence, nacacancel
intermolecular forces order
ionic bonding
hydrogen bonding
dipole-dipole interaction
Van der Waals dispersion forces
INAY HA DOON VA?
the more the no. of carbon, the ___ the boiling point
HIGHER
bumababa ang boiling point kapag nagkakaroon ng ___ sa carbon chain
BRANCHING
✓due to MORE ENERGY that is required to overcome the INCREASED FORCES OF ATTRACTION caused by long carbon chains
- boiling point ↑ as the number of carbon atoms ↑
✓ it causes the SURFACE AREA of the molecules to DECREASE thereby DECREASING THE FORCES OF ATTRACTION between individual molecules
- boiling point ↓ in the PRESENCE OF BRANCHING
✓due to the ATTRACTION OF POSITIVE end of one molecule to the NEGATIVE end of another molecule
- boiling point ↑ as the POLARITY OF THE SUBSTANCE ↑
✓due to DECREASE in the VAPOUR PRESURE of the liquid
- boiling point ↑ in the PRESENCE OF NON-VOLATILE IMPURITIES
✓due to the INCREASE in the VAPOUR PRESSURE of the liquid
- boiling point ↓ in the presence of volatile impurities
- the temperature at which a SOLID compound is DIRECTLY CONVERTED to its LIQUID STATE
MELTING POINT
- a PURE CRYSTALLINE compound has a SHARP MELTING POINT and it completely melts within a narrow range of temperature NMT ____
0.5 - 1°C
- if a compound melts over a VERY NARROW RANGE, it is assumed that the compound tested is relatively ____
PURE
- if a compound melts over a _________, it is assumed that the compound tested is relatively PURE
VERY NARROW RANGE
- the presence of _____ usually DEPRESSES the melting point and may INCREASE THE MELTING POINT RANGE
IMPURITIES
in the identification of an impure compound, the actual melting point is compared to its
THEORETICAL MELTING POINT VALUE
✓the presence of _____, and especially hydrogen bonding, leads to a HIGHER MELTING POINT of compounds
POLARITY
________ between molecules may still
affect the melting point of a compound (ionic bonding results to higher melting point)
INTERMOLECULAR FORCES OF ATTRACTION
✓difference in the ________ (eg. isomers) may result to a difference in their melting points (difference in the arrangement of their structures even both are pure)
CONFIGUARTION OF CA COMPOUND
BP:
tert-butyl alchohol
82.3
BP:
chloroform
61.2
BP:
n-hexane
68.7
BP:
methanol
64.7
MT:
salicylic acid
211.0
MT:
benzoic acid
122.4
MT:
glucose
146.0
MT:
fructose
103.0