Experiment#1: Boiling Point Flashcards
Enumerate the 4 Factors Affecting BP
- Atmospheric Pressure
- IMFA
- Molecular Structures
- Impurities (added during post-lab discussion)
IONIC vs. COVALENT
In comparing Ionic and Covalent compounds, which ones would have a lower BP, and which ones would have a higher BP?
Ionic - HIGH BP
Covalent - LOW BP
ATMOSPHERIC PRESSURE [ATM]
Above sea level, ATM ____ and BP ____.
ABOVE SEA LEVEL:
ATM decreases, BP decreases.
ATMOSPHERIC PRESSURE [ATM]
Below sea level, ATM ____ and BP ____.
BELOW SEA LEVEL:
ATM increases, BP increases.
ATMOSPHERIC PRESSURE [ATM]
Being that the BP of water is 100 °C at sea level, what then would be the (hypothetical) BP of water should you boil it at the top of Mount Everest?
A) 300 °C
B) 120 °C
C) 68 °C
D) 250 °C
C) 68 °C, because ATM decreases above sea level, therefore BP also decreases.
Mount Everest is at a high altitude, well above sea level.
ATMOSPHERIC PRESSURE [ATM]
Being that the BP of dodecane is 213 °C at sea level, what then would be the (hypothetical) BP of dodecane should you boil it at the bottom of the Mariana Trench?
A) 200 °C
B) 374 °C
C) 118 °C
D) 95 °C
B) 374 °C, because ATM increases below sea level, therefore BP also increases.
The bottom of the Mariana Trench is well below sea level.
INTERMOLECULAR FORCES OF ATTRACTION [IMFA]
If a compound has strong IMFA, its BP therefore is ____.
HIGH | The stronger the IMFA, the higher the BP
INTERMOLECULAR FORCES OF ATTRACTION [IMFA]
If a compound has weak IMFA, its BP therefore is ____.
LOW | The weaker the IMFA, the lower the BP
TRUE or FALSE | EFFECT OF SURFACE AREA
Molecules with larger surface area have stronger IMFA therefore higher BP.
TRUE
EFFECT OF BRANCHING
If a molecule has branches (meaning: chains of other molecules attached to the parent molecule), it therefore has a ______ surface area, meaning a ______ BP.
DECREASED surface area = DECREASED BP
POLAR vs NONPOLAR
In comparing Polar and Non-Polar molecules, which ones would have a higher BP?
Polar - HIGHER | Because they have stronger IMFA compared to Non-Polar molecules.
A molecule having stronger Intermolecular Forces of Attraction means it requires a higher amount of energy for said forces to be broken down.
TRUE or FALSE | EFFECT OF POLARIZABILITY
An increase in polarizability means a decrease in IMFA and therefore a decrease in BP.
FALSE, increased polarizability = increased IMFA = increased BP
INTERMOLECULAR FORCES OF ATTRACTION [IMFA]
CH₃CH₂OH (Ethanol) vs CH4 (Methane)
Ethanol is a polar molecule.
Methane is a non-polar molecule with the existence of only London Dispersion Forces in its IMFA.
Identify the FF:
A) What IMFA does Ethanol contain?
B) Now knowing the IMFAs of both compounds, which of the two, therefore, has the lower BP?
A) Ethanol contains Hydrogen Bonding forces because its chemical formula contains an H bonded to an O.
B) Methane. Because Ethanol is both polar and contains the strongest IMFA as compared to Methane, which contains only the weakest IMFA (London Dispersion Forces)
CHANGE OF STATE:
The transition from a solid to a liquid to a gas, and the reversal, represent ______ ___ - meaning there is only a change in the form or state of the substance.
Physical Change
CHANGE OF STATE:
The following are examples of changes of states that require energy. What is this term called?
- Melting [Solid to Liquid]
- Vaporization [Liquid to Gas]
- Sublimation [Solid to Gas]
Endothermic
