BIO 311 Chapter Notes - Chapter 3.9: Butane, Covalent Bond, Titration Curve
Water is an excellent solvent because
of its ability to engage in:
1. Hydrophobic interactions with
hydrocarbons
2.Covalent bonds with ionic compounds
3. Electrostatic interactions with polar
compounds
Water is an excellent solvent because
of its ability to
The heat of vaporization of H2O is 2,260
J/g while that of CH3(CH2)2CH3 (butane) is
381 J/g. The primary reason for this large
difference is the ability of H2O molecules
to:
1) readily dissociate into H+ and OH2)
form hydrogen bonds with H2O
3) form ionic bonds with H2O
4) readily dissociate into H3O+ and OH5)
form covalent bonds with H2O
The heat of vaporization of H2O is 2,260
J/g while that of CH3(CH2)2CH3 (butane) is
381 J/g. The primary reason for this large
difference is the ability of H2O molecules
to:
1) readily dissociate into H+ and OH2)
form hydrogen bonds with H2O
3) form ionic bonds with H2O
4) readily dissociate into H3O+ and OH5)
form covalent bonds with H2O
Acids, Bases, and pH
• The ioheial popeties of a ipotat biomolecules depends on their
acid-base properties
• A aid is a poto hdoge io doo, ad a ase is a poto aepto
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• Ho eadil aids o ases lose o gai potos depeds o the heials
themselves
• Stog aids opletel dissoiate i ater, while practically no dissociation is
observed for weak acids
HA ➜ H+ + AAcid
Conjugate base
Ka = [H+][A-]/[HA]
• The Ka alue, o the aid dissoiatio ostat, is a easue of the aout of
hydrogen ion released when a given amount of acid is dissolved in water, i.e. the
strength of the acid
• Suae akets efe to ola oetatios
• The lage the Ka alue, the stoge the aid
p. 47
Hydration of H3O+ in H2O
• The peedig aid-base reaction is a proton-transfer reaction in which water
acts as a base as well as the solvent
• A oe oet a of itig the aid dissoiatio euatio is as follos:
• The otatio a efes to solutes i aueous solutio, heeas l afte ate,
refers to water in the liquid state
• Fee hdoge ios do ot eist i solutio; ee the hdoiu io HO+ is a
underestimate of the degree of hydration of hydrogen ion in aqueous solution
• All solutes ae etesiel hdated i aueous solutio
What is pH?
• Wate does ot solel at as a solet i aid dissoiatio eatios, ad a at
as a acid or base itself
• The etet of self dissoiatio of ate to hdoge io ad hdoide aio, is
small, but the fact that it does take place determines important properties of
many solutes
H2O ➜ H+ + OH-
Hydration of H3O+ in H2O
Fig. 2-11, p. 48
• Both the H+ o HO+ ad OH- are associated with several water molecules, as are
all ions in aqueous solution, and the water molecule in the equation is itself part
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Document Summary
Water is an excellent solvent because of its ability to engage in: hydrophobic interactions with hydrocarbons. 2. covalent bonds with ionic compounds: electrostatic interactions with polar compounds. Water is an excellent solvent because of its ability to. The heat of vaporization of h2o is 2,260. Answers: ph = 3, ph = 10. Henderson-hasselbalch equation: the e(cid:395)uatio(cid:374) is useful i(cid:374) predicting the properties of buffer solutions used to control the ph of reaction mixtures. Also use the henderson-hasselbalch equation to calculate the values of the ph at these points: 0. 1 mol of naoh is added, 0. 7 mol of naoh is added ph = pka + log [a-]/[ha] When 0. 1 mol of base are added, 0. 1 mol of acetic acid reacts with it to form 0. 1 mol of acetate ion, leaving 0. 9 mol of acetic acid. The composition is 90% acetic acid and 10% acetate ion ph = 4. 76 + log 0. 1/0. 9 ph = 4. 76 + (-0. 95) ph = 3. 81.
