Find the pH of a 0.25 M solution of lactic acid, HC3H5O3 (Ka = 8.3 x 10 -4 ).

pH → 1.83

Explanation:

Let's write the lactic acid as HLac, because it is a monoprotic weak acid.

HLac + H₂O  ⇄  H₃O⁺  +  Lac⁻      Ka

Initially we have 0.25 moles, so x amount has reacted. At the end, when the equilibrium is finished, we may have (0.25 - x) moles of acid, x moles of protons have been released and x moles of lactate were formed.

In order to find x, we use the acid constant, Ka. The expression for Ka is:

Ka = [H₃O⁺] .  [Lac⁻] / [HLac]

8.3×10⁻⁴  = x² / (0.25-x)

8.3×10⁻⁴ (0.25 - x) = x²

8.3×10⁻⁴ . 0.25 - 8.3×10⁻⁴x - x² → this is a quadractic function

a = -1,  b = 8.3×10⁻⁴, c = 2.07×10⁻⁴

We solve: (-b - √(b² - 4ac) / (2a)

(-8.3×10⁻⁴ - (√ ((8.3×10⁻⁴)² - 4 (-1) (2.07×10⁻⁴) ) / (2 . -1) = 0.0148

[H₃O⁺] = 0.0148 M

- log [H₃O⁺] = pH → - log 0.0148 = 1.83

when—without warning—something provokes your anger, you may struggle not to succumb to it. since what typically makes you mad is feeling powerless in the face of what seems unfair, your anger is mostly an attempt at a “quick fix” to right the balance. it’s as though you’re raising a fist in protest, proclaiming that you’re not going to capitulate to such injustice.

there are, however, a multitude of problems related to this immediate, push-back reaction of anger. and probably the key one is that almost never does it resolve the issue that gave rise to it. such reactive anger is probably best understood as self-defeating. as david burns, the author of the seminal self- book feeling good, observes: if realistically, acting on your anger is to make any sense, it needs to meet two criteria—which, in almost every case, is frankly impossible. that is, your anger must:

be directed toward a person who has intentionally (and needlessly) behaved in a hurtful way toward you; and

be beneficial or advantageous to you (i.e., assist you in achieving a desired goal).

i think you’ll agree that only rarely can you claim that your anger is both warranted and , whether to yourself or the relationship.

so let me offer you a two-step alternative to abandoning your better judgment and giving in to the temptation of anger—one that should neutralize your anger in seconds. or, when you’re really angry, in minutes.

but keep in mind that you must really want to execute these steps, be sufficiently motivated to perform them. which means overcoming more unconscious resistance than you might ever have imagined. because there are many immediate “advantages” of anger that can interfere with your resolve, i’ll suggest a few of them that might interfere with your employing this powerful method to rid yourself of counter-productive anger.

explanation:

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.