MES is a buffering agent commonly used in biology and biochemistry. It has a pKa of 6.15. Its acid form has a molar mass of 195.2 g/mol and its sodium salt (basic form) has a molar mass of 217.22 g/mol. What is the pH of a 0.10 M solution of MES that is an equimolar solution of MES and its conjugate base?

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.