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Kris Quinlan

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LECTURE 5 – States of Matter
Slide No. Notes
2-intermolecular forces determine state of matter
-for instance, if intermolecular forces very strong, state of matter is
3- 2 molecules approach each other, not bonding
5-opposites attract
-the stronger the charges, the stronger the attraction
-mixtures are where dipole-dipole interactions occur: need for ions and
polar molecules
6-leftside: lower energy state with many attraction forces
-rightside: dipoles are moving around
-H-bonding present in DNA, between strands
-F, N, and O are the only elements that can H-bond because they are in
the first row of the periodic table, so they are small, so H can get
close to the nucleus of these elements, therefore closer attraction
7- how readily dispersed
8 -range of ion-dipole strength because it depends on charge of ion, and
size of molecule’s dipole
-London dispersion forces range from smaller to larger than dipole-
dipole’s range
-Large molecules have strong dispersion forces because of the
presence of many electrons
-For similarly sized molecules, dipole interactions are stronger
9-as number of carbon atoms increase, boiling point increases
-the bigger the molecule, the more attractions between partially
negative and partially positive sides of neighbouring molecules
-boiling = causing molecules to move faster, to move apart, to change
in the gas phase – NO BONDS are broken
-straight-chain versus branched pentane – the former has a higher
surface area
-therefore, shape matters in both dipole moments and dispersion
forces’ strength
10 -Ans: D
-no dipole moment therefore will look at dispersion forces
-most electrons means strongest dispersion forces
12 -plateaus are where melting and boiling occurs
-energy goes into overcoming intermolecular forces
13 - Ex. sugar cube into coffee spontaneously dissolves
14 - upward-pointing arrow – depends on temperature if spontaneous or not
15 -Ans: C
-Volume does change – ex. liquid to gas
16 -equilibrium – having evaporating water while also have gases
condensing present
-higher temperature shifts KE distribution higher
-vapour pressure can only be measured in closed container
18 -Ans: B
-More energy needed to get B into gas phase
-A is true because A needs less energy, therefore more liquid
molecules of A than gas molecules
-C – increasing temperature changes distribution – both will get into
gas phase
-Ans2: D
19 -diethyl ether – dipole-dipole, and dispersion (between the ethyl
-ethanol – H-bonding
-water – H-bonding
-water is the better H-bonder because the –OH only H-bonds, the other
part of ethanol does not H-bon
-EX1: the first has ionic bonding, the second dipole-dipole SO MgCl2
has higher BP
-EX2. the first has H-bonding, the second dipole-dipole SO the first
has higher BP
-EX3. both tetrahedral therefore distinction rests with dispersion
forces (or rather, the number of electrons)
-Ans: B – since CCl4 is larger, more electrons, therefore higher MP
20 -the first has dipole-dipole and dispersion forces
-the second h-bonding
-the third metallic bonding
21 -in the water picture, water is creeping up the sides
-in the mercury picture, different from water because mercury wants to
minimize interactions with the glass
22 -Ans: A
-Test tube A fills up more slowly
23 - the left picture is an example of a crystalline solid; the right is an example
of an amorphous solid
24 - molecular solid – how low depends on the intermolecular forces
25 -higher MP – must break covalent bonds
-these four are all allotropes of carbon
-graphite is a good lubricant because sheets of it slide against each
26 -sodium in the first column; magnesium in the second column – so Mg
has more electrons, moreglue to hold these molecules together
-shape is changed but bonding unchanged
29 -phase diagram specific to substance
-solid phase – where particles are closest together
-triple point – all three states existing simultaneously
30 -Ans1: D
-Ans2: B
31 -the FP slope is negative because increased pressure favours the liquid
-liquid water denser than solid water
32 -example of supercritical fluids as solvents is to decaffeinate coffee/tea
-CO2 is easy to separate from the coffee beans, because they can just
be evaporated
-The middle picture of the diagram – gas and liquid interphase
-In the third picture – no distinction between the two states
33 -Ans1: D
-For instance, liquid water is denser than solid water
-Ans2: D