Red Pen Prep

From the reel · Acid series · Part 5

Bicarbonate vs CO₂ in your blood20 : 1
A frame from the reel on bicarbonate and CO₂

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Your blood keeps about 20 bicarbonates for every dissolved CO₂.

pH 7.4 is 1.3 units above the pKa of 6.1, and 101.3 ≈ 20. One line, pH − pKa = log(base/acid), runs every buffer question.

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3,122 questions in the Pass, all corrected like the three below. The questions here are optional.

Now use it. Three questions from the course.

Same reasoning, new numbers. Pick an answer: the red pen names the trap and marks the line that decides it.

Question 1 of 3from the course, Chem/Phys

A buffer is made from a weak acid with pKa 6.8 and its conjugate base. At pH 7.8, what is the ratio [base]/[acid]?

Pick one. The red pen does the rest.

Question 2 of 3from the course, Bio/Biochem

Acetic acid has a pKa of 4.76. In a buffer held at pH 5.76, about what fraction of the acetate is in the deprotonated (conjugate base) form?

Pick one. The red pen does the rest.

Question 3 of 3from the course, Chem/Phys

Acetic acid is titrated with sodium hydroxide. Which indicator, with its color-change range, best signals the equivalence point?

Pick one. The red pen does the rest.

You just did what the Pass does 3,122 times.

Same red pen, every question in the course: Bio/Biochem, Chem/Phys, Psych/Soc and CARS.

  • Every wrong choice named for the trap it sets
  • The deciding line marked on every question
  • Every miss back on day 1, 3 and 7
  • All four sections, 11 full-length exams, a day-by-day plan

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