Question

The value of Δ G ° ' for the conversion of 3-phosphoglycerate to 2-phosphoglycerate (2PG) is + 4.40 kJ/mol . If the concentration of 3-phosphoglycerate at equilibrium is 2.45 mM , what is the concentration of 2-phosphoglycerate? Assume a temperature of 25.0 ° C .

Answer 1

Answer:The concentration of 2-phosphoglycerate is 0.415 mM

Explanation:

$3-phosphoglycerate\rightleftharpoons 2-phosphoglycerate$

Relation between standard Gibbs free energy and equilibrium constant follows:

$\Delta G^o=-RT\ln K$

where,

$\Delta G^o$ = Standard Gibbs free energy = +4.40  kJ/mol = 4400 J/mol  (Conversion factor: 1kJ = 1000J)

R = Gas constant = $8.314J/K mol$

T = temperature = $25^0C=(25+273)K=298 K$

Putting values in above equation, we get:

$4400J/mol=-(8.314J/Kmol)\times 298K\times \ln K$

$\ln K=-1.776$

$K=0.169$

$K=\frac{ 2-phosphoglycerate}{3-phosphoglycerate}$

$0.169=\frac{ 2-phosphoglycerate}{2.45mM}$

$2-phosphoglycerate}=0.415mM$

Thus the concentration of 2-phosphoglycerate is 0.415 mM