5. what concentration of acid must be added to change the ph of 1 mm phosphate buffer from 7.4 to 7.3 (pkas of the phosphate buffers are 2.12, 7.21 and 12.67)?

Explanation:

According to the Henderson-Hasselbalch equation, the relation between pH and is as follows.

               pH =

where,     pH = 7.4 and = 7.21

As here, we can use the nearest to the desired pH.

So,      7.4 = 7.21 +

             0.19 =

            = 1.55

1 mM phosphate buffer means + = 1 mM

Therefore, the two equations will be as follows.

            = 1.55 ............. (1)

  + = 1 mM ........... (2)        

Now, putting the value of from equation (1) into equation (2) as follows.

             1.55 = 1 mM

                        2.55 = 1 mM

                              = 0.392 mM

Putting the value of in equation (1) we get the following.

                     0.392 mM + = 1 mM

                          = (1 - 0.392) mM

                              = 0.608 mM

Thus, we can conclude that concentration of the acid must be 0.608 mM.

the potential energy of the reactants is 200j.

from the energy diagram, the energy of the product formed is 350j; this means that, this reaction is an endothermic reaction, because it absorbs energy from its environment.

answer: e.   sour taste

explanation: acids are those substances which dissociates in water to give ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. acids are sour in taste. example: hcl

bases are those substances which dissociates in water to give ions or accepts ions. as they dissociate to give ions, they act as electrolytes and thus are electrically conductive. bases are bitter in taste. bases are slippery in nature.