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45 Cards in this Set
- Front
- Back
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Different compounds with the same molecular formula
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Isomers
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two major classes of isomers are
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1.)Constitutional/structural isomers- have different IUPAC names, can have different functional groups and different physical properties.
(meisenberg calls these positional isomers) 2.) Stereoisomers- have the same IUPAC name (with the addition of cis/trans, E/Z). They always have the same functional groups. |
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Minor differences in 3-D structure can result in vastley different
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Chemical and physical properties.
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What are the differences between cellulose and starch if they have the same molecular formula?
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(Starch (both Oxygen are equitorial) and Cellulose (one is axial the other is equitorial).
As a result, Cellulose forms flat structure while starch forms a helical structure. |
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Geometric isomers arise as a result of a rigid bond. What are the three examples of this?
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Double bonds, triple bonds, and ring structures.
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Geometric isomers are synonymous with
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Stereoisomers (cis/trans, E/Z)
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Constitutional isomers are synonymous with
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Postitional and Structural isomers
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What is a chiral molecule?
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A molecule which has a non-superimposable mirror image.
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Chiral molecules must have a chiral center (usually chiral carbon) which means?
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that all the substituents attached must be different than one another.
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What are two ways that ensure a molecule is ACHIRAL?
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1.) If any of the substituents repeat or if there is a PLANE OF SYMMETRY.
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Enantiomers are
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stereoisomers whose molecules are nonsuperimposable
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How do you draw out all the enantiomers of a chiral molecule?
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you interchange any two groups at the chiral center and you have a new enantiomer.
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What are the properties of enantiomers?
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They have equal physical and chemical properties.
-identical melting and boiling points -solubilities -react in the same way -polarize light in the same direction and in the same amount. |
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Diasteromers are
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stereoisomers which are NOT mirror images of eachother.
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Why is chirality important biologically?
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The binding of receptors is usually chiral specific.
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Do enantiomers have similar physical and chemical properties? do diastereomers?
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Yes ; No
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Stereogenic centers
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are common in biologically active molecules with rings.
Stereogenic centers are chiral carbons in a ring structure. |
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Water is amphiprotic, what does this mean?
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It can act both as a base or as an acid. It neutralizes acids and bases.
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Water autoionizes, what does this mean?
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molecules of water react with eachother to form ions.
H20 --> H30+ and OH- |
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what is teh concentration of hydroxide and hydronium ions in water
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1.0 x 10-7 M or pH 7
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pH =
pOH = pH + pOH = |
-log [H+]
-log [H3O+] 14 |
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What is the result of High H+ ions in the body?
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Low pH which casese cell and tissue damage, alters proteins, interferes wtith normal physiological function.
Rarely are excess [OH] a problem. |
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The blood's normal pH is ____.
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7.4
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What buffer is in place to mantain blood's pH?
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bicarbonate [HCO3]-[CO2]
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If the pH falls below 7.3 this condition is called?
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Acidosis
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What are the normal pH, HCO3- and CO2 concentrations and values?
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7.4; 24 mM; 1.2 mM
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What is the bronsted lowry definition of a base? Acid?
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A proton donor is an acid.
A proton acceptor is a base (NH3 accepts H+). |
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The blood's normal pH is ____.
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7.4
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What buffer is in place to mantain blood's pH?
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bicarbonate [HCO3]-[CO2]
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If the pH falls below 7.3 this condition is called?
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Acidosis
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What are the normal pH, HCO3- and CO2 concentrations and values?
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7.4; 24 mM; 1.2 mM
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What is the bronsted lowry definition of a base? Acid?
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A proton donor is an acid.
A proton acceptor is a base (NH3 accepts H+). |
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Strong acids and strong acids
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dissociate completetly in water. No equilibrium is setup.
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Weak acids and weak bases
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do not completely dissociate in water and setup an equilibrium. VERY COMMON IN BIOCHEMISTRY.
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How is acidity normally expressed? What do larger and smaller numbers mean?
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pKA.
The smaller the pKA the stronger the acid. |
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Complete the sentence.
The stronger the acid the weaker the ________. The weaker the acid the stronger the _______________. |
conjugate base (and vice versa)
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How do you calculate Ka (strength of acid)
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Ka = [A-][H30+] / [HA]
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The strength of a base can be determined by calculating the Kb. What is the equation?
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Kb = [OH-][BH+] / [B]
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In the case of weak acids, their Ka values are ALWAYS
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less than 1.
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How do we know which weak acid is stronger?
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all will be less than 1. The larger of the numbers.
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How do we describe the relationship between pH, pKa, and buffer concentration?
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Henderson Hasselback equation
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What is the Henderson Hasselback equation?
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pH= pKa + log [A-]/[HA]
HA= weak acid A- = conjugate base |
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what are buffers?
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Aqueous systems that resist changes in pH when small amounts of acid or base are added to the system.
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What are the components of a buffer?
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a weak acid (carbonic acid) and its conjugate base (bicarbonate).
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How effective are buffers?
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they can mantain pH within 1 pH unit of the pKA
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