Water

Question 1

How does waters structure relate to its polarity and dynamics

Answer 1

tetrahedral parent geometry, bent molecular geometry. Lone pairs make it polar.
Diamagnetic since no unpaired electrons, hence repels magnetic field
when exposed to negatively charged balloon, positive dipole of water attracted to it

Question 2

6 props of water?

Answer 2

cohesion
high heat capacity
high latent heat
high boiling point
relative density of water and ice
solvent ability

Question 3

describe cohesion

Answer 3

ability of water to stick to itself

Question 4

applications of adhesion

Answer 4

water transport in plants
surface tension (stronger bonds at surface) so insects can walk on water

Question 5

describe heat capacity

Answer 5

amount of energy required to change temp of a substance

-high in water due to strnog H bonds

Question 6

applications of heat capacity

Answer 6

bodies of water can retain temperature relatively well in spite of changes to air temp
water bodies help regulate temp. when hot it absorbs heat and when cold it releases heat
aqueous env of cells - heat regulation

Question 7

describe relative density of water and ice

Answer 7

ice held in crystal lattice structure. increased AKE with increased temp which breaks some H bonds upon melting - lower density than ice

Question 8

applications of density of water?

Answer 8

ice floats on water, insulates water underneath and enables life.
if it didn’t, ice would melt less quickly, ocean would freeze, life wouldnt exist

Question 9

describe latent heat

Answer 9

during a state change, water absorbs energy but remains at constant temp until the state change is complete
latent heat of fusion vs vaporisation
-high for water due to strong H bonds
-higher for vaporisation than fusion as all, vs some, H bonds must break.

Question 10

applications of latent heat?

Answer 10

on dry days, theres not much water in air
on humid days theres lots of water in the air. Therefore the total energy to evaporate all that water increases adsweating isnt effective

Question 11

all metabolic reactions in orgaisms…

Answer 11

happen in solution in cells

Question 12

describe dissolutio of polar compounds

Answer 12

form dipole dipole/h bonds

Question 13

describe dissolution of ionic compounds

Answer 13

ion-dipole interactions occur. if strong enough to overcome H bonds of water, ions pulled out of lattice and form hydration shells (surrounded by h2o based on dipoles)

Question 14

describe dissolution of non polar compounds

Answer 14

only form disp forces. not strong eough to overcome h bonds of water so dont mix

Question 15

describe dissoltion of amphipathic compounds

Answer 15

polar parts face water, non polar parts don’t.
they can form
-single layered clusters (tails interact w water as little as possible)
-micelles (single layered cirlce)
-liposome (double layered, with water in the middle)
-plb

Question 16

describe how water ionises

Answer 16

first into H+ andOH-, the H+ combines with water to form H3O+

Question 17

describe extent of ionisation of water

Answer 17

very small, dissociation constant is 1.8x10^-16

Kw = 10^-14

Question 18

what else about water do you need to know?

Answer 18

amino acid’s acid base properties and buffer solutions