The change in the standard Gibbs free energy (ΔGº) for the dissociation of nitrous acid (HNO2) at 298 K is 19.09 kJ. If the pH of the solution after equilibrium is reached is 1.30 and the NO2 – concentration at equilibrium is 0.00060 M. What is the equilibrium concentration of HNO2? Hint: Use pH to determine the equilibrium concentration of H+ .

Consider a culture medium on which only gram-positive organisms such as staphylococcus aureus colonies can grow due to an elevated nacl level. a yellow halo surrounds the growth, indicating the bacterium fermented a sugar in the medium, decreasing the ph as a result and changing the color of a ph indicator chemical. this type of medium would be referred to as a differential and enrichment culture.