More Questions Flashcards
what is standard free energy equation
delta G’ = -RTlnK
a chemical reaction for which the associated enthalpy change is positive:
A) cannot occur spontaneously
B) may occur spontaneously if coupled to reaction in which enthalpy change is negative and of greater magnitude
C) raise surrounding temp
D) inevitably occur spontaneously
B
a chemical reaction for which the associated free energy change delta G is large and negative A) cannot occur spontaneously B) is likely to be irreversible C) will inevitably occur spontaneously D) will occur rapidly
B -
when is delta G small and reversible
when all difference in ratio to products
small conc change in reactants/products can reverse delta G
when is delta G large and irreversible
when large differences between reactants/products
what statement about ATP is correct
A) ATP can diffuse through membranes
B) ATP is considered a low energy phosphate compound
C) ATP is present at high conc in cell
D) Hydrolysis of ATP is strongly exergonic
D
Which of the following statements best describes how a reaction is likely to behave if it has a large, negative value for G?
a) The reaction will be at equilibrium.
b) The reaction is likely to happen to a small extent, with only a small amount of product formed.
c) The reaction will happen to a moderate extent, with about as much product being formed as reactant being left.
d) The reaction is likely to happen to a large extent, with large amounts of product formed
D G is large and negative equilibrium lies towards right favours foward reaction product formation spontaneous reaction
At Keq the value of the change in free energy for a chemical reaction is:
a) zero
b) greater or less than zero but remains at a stable value
c) does not change with respect to energy transfer from coupled reactions
d) The point at which the concentration of reactants and products are equal.
A g K is equilibrium constant determined from [C][D]/[A][B] products/reactants no net free energy transfer
what is delta G when a reaction is at equilibrium
delta G = 0
forward rate = backwards rate
What is the value of DGo’ (kJ/mol) at equilibrium for the reaction
A + B C + D with the following conditions:
A = 0.1mol.l-1 B=0.25mol.l-1 C=0.3mol.l-1 D=0.6mol.l-1 R= 8.3 JK-1.mol-1 T= 298 K
WATCH UNITS
must divide -RT by 1000
-RT = -(8.3 x 298)/1000 = -2.5kJ.K-1.mol-1
Keq = ((0.3x0.6)/(0.1x0.25)) = 1.8/0.025 = 72mol.l-1
ln(72)= 4.3
DGo’ = -2.5 x 4.3 = -10.6kJ.mol-1
if delta G is negative is reaction spontaneous
yes
larger the value more change of being irreversible
more products are formed
Which of the following options provides the correct value of DGo’ (kJ/mol) at equilibrium for the reaction A + B C + D with the following conditions:
A = 0.75mol.l-1 B=0.15mol.l-1 C=0.08mol.l-1 D=1.2mol.l-1 R= 8.3 JK-1.mol-1 T= 298 K
a) +0.43kJ.mol-1
b) -0.43kJ.mol-1
c) +0.88kJ.mol-1
d) -0.88kJ.mol-1
A
What is a polar molecule?
a) a molecule with no charge
b) a molecule with opposite charges at opposite ends
c) a molecule with identical charges at opposite ends
d) molecule with an unequal number of protons and electrons
A
What how does water arrange around ions?
a) the more negative atoms attach to positive ions
b) the more positive atoms attach to negative ions
c) water forms a hydration shell
d) all of these answers are true
D
Which is TRUE regarding the structure of hydrogen bonds?
a) Hydrogen bonds can only arise from the covalent interaction between oxygen and hydrogen atoms.
b) It is only the hydrogen atoms of a water molecule which interact with polar molecules
c) Hydrogen bonds involve a linear arrangement of one hydrogen atom between two electronegative atoms
d) Hydrogen bonds are angled at 104.3o
C
how are hydrogen bonds formed
hydrogen atoms are shared between 2 electronegative atoms
bonds are linear
Which of the following statements about amino acids is correct?
a) Amino acids are classified according to the structures and properties of their side chains.
b) Amino acids are uncharged at neutral pH.
c) Amino acids in proteins are mainly in the D-configuration.
d) Twenty four amino acids are commonly used in protein synthesis.
A
All amino acids contain an alpha carbon bonded to the following structures:
a) an amino group (-NH2), a carboxyl group (-COOH), a hydrogen (-H), a side chain (-R)
b) an amide group (-CONH2), a carboxyl group (-COOH), a hydrogen (-H), a side chain (-R)
c) an amino group (-NH2), a carboxyl group (-COOH), a hydroxyl group (-OH), a side chain (-R)
d) an amide group (-CONH2), a hydrogen (-H), a side chain (-R)
A
what are proteins and polypeptides in humans made up of
20 different L-amino acids
define hydrophobic
no net charge
what are Aliphatic (linear hydrocarbon chain) or aromatic (unsaturated chemical compounds characterized by
one or more planar rings of atoms joined by covalent bonds side groups
describe methionine
amino acid the starts translation
contains sulphur
describe polar amino acids
soluble in water
class capable of creating redox sensitive disulphide bridges
one N,O, S in R side chain d
