This video picks up from MCAT Math Part 8 – Logs and Negative Logs showing you how to solve questions where the log value is provided. Instead you’re asked to solve for the anti-log value in questions relating to ion concentration and Ka values.

Anti-logs, just like logarithms, are difficult to calculation without a calculator UNLESS you know the tricks and shortcuts to apply. Watch the video below to learn how to tackle these MCAT style questions.

## Anti-logs Without A Calculator

(click to watch on YouTube or click for Video Transcript)

## MCAT Style Question Covered In This Video:

**Chemistry Buffers/Ka Question: **Find the ka of an acid whose buffer has a pH of 4.19 in a solution containing equal moles of acid and conjugate base.

**<– Watch Previous Video:** Logarithms and Negative Logs

–> **Watch Next Video:** Decimals & Exponents

**Click HERE**for my FREE MCAT Math Quiz

**This is Video #9 in my MCAT Math Without A Calculator tutorial series. Click HERE for the entire series**

How did you decide that the answer was # x 10^-5 rather than # x 10^-4? Because the range for the pKa was between 4 and 5, so what made you conclude that the pKa was closer to 5 than to 4?

I think you may have misspoke… 6.46 is closer to 5 than to 8 🙂 These videos are very helpful!!

At 3:48, how did you just concluded that 4.19 will give you a number (#) x 10^-5?

I know that is what the answer ends up being, but how did you just jump to that?

See the math cheat sheet

Hi Leah, I am confused as to what the .1 .3, and .5 values refer to? is that the value of the pKA?

See the MCAT math cheat sheet

what is the value of 10 raised to -0.2????

For the MCAT simply estimate that it’s between 10^0 and 10^-1. That’s between 1 and 0.1