MCAT Math Vid 8 Logarithms and Negative Logs in pH and pKa Without A Calculator
Leah here from leah4scimcat and in this tutorial, i'll show you how to tackle logarithms style tackled questions without a calculator as it may show up on your mcat.Logs are tricky and unlike other questions that you can fallback on the long mathematical process like multiplication, division, addition, subtraction, with logs, you either know it or you don't! so i wanna make sure that if you're ask to calculate anything like a ph or a pka on your mcat, you know what to do and you know how to do it quickly and confidently.
And the good news is that on the mcat, when you're ask to solve a log type of question, the answer choices will be so far apart that if you quickly get a value that is close enough, you're good enough to have the answer and you're able to move on and devote more time to your next question.You may find yourself faced with the question that reads find the ph of a 2.3 x 10 molar solution of naoh.The chemistry portion of this question will be tackled in my chem tutorials at leah4scichemistry.
But for now let's focus on math.To find the ph of the solution we first have to see the ion concentration given.Since we're given an naoh or oh minus concentration, we'll go for the minus oh concentration to the poh, from there we'll get to the ph because ph plus poh is fourteen.But the difficult part is going from the oh minus concentration to the poh.We'll use the following formula poh is equal to negative log of the oh minus concentration which in this question is negative log two point three.
Times ten to the minus 4 log 2.3x104.Great! i have the setup but i don't have the calculator, how do i proceed so how do we find the negative log of this value let's focus on the trick first and then we'll come back to solve this question.Here's what you have to know about logs on the mcat.When given log of a number, you're really given log base ten and this tells you, ten to the what power is equals to this number.Don't worry, we're not going to the long tedious solving of logs, instead we'll understand.
What's going on and then i'll show you a quick shortcut.This is easy for simple questions, for example, given log a hundred, ask yourself, ten raised to what power is equal to a hundred 100 since ten times ten or ten squared is a hundred, the answer is 2.What about the log of a thousand 1000 ten to the what power is equal to one thousand.Well ten times ten times ten or ten to third equals to a thousand and so the answer is 3.Now what about the negative logswhile negative.
Logs appear to be more difficult its actually the same thing with a negative before the power.So for example negative log of zero point one is equal to one because one times ten to the minus one is equal to zero point one.Another way to think of this is turn this into scientific notation.Zero point one is really one times ten to the minus one so we already have ten raised to a power of a negative number and here's the trick when your number is written out in scientific notation, you.
Have ten to the negative number.Just circle that number and that is your answer.Let's try this shortcut again say you're told negative log of one times ten to the minus four.We have one times ten to a negative power, circle that power and the answer is four.What about negative log of one times ten to minus eleven again, ten to the negative number, circle that number and the answer is eleven.Let's apply this to something you already know.A neutral solution at room temperature will have a ph at seven.This solution will also have an equivalent h plus and oh minus concentration.
Each equaling one times ten to the minus seven.So let's prove this mathematically.The ph is equal to negative log, the h plus concentration which is equal to negative log one times ten to the minus seven.We have our value set up at one times ten to a negative power, grab that power and the answer is seven.But what if we don't have one times ten to a power and instead have two point three times ten to a power such as the example given.This is where we are going to apply additional tricks and simplification keeping in mind.
That we only need an answer that is close enough.Let's start with something simple say we're trying to solve the negative log of four point five times ten to the minus three.First we wanna get a ballpark but we need this expression to be setup as one times ten to a negative power so i wanna find the inbetween values by taking four point five rounding it down to one and up to ten because this way my number will start with the one.If i round it down to one, i get one times ten to the minus three and if i round it up.
To ten i get ten times ten to the minus three.But ten times ten to a power is not a proper scientific notation so we want to divide the ten by ten giving me one and then multiply the exponent by ten or raise it by one power giving me times ten to the minus two.Ten times ten to the minus three is the same thing of saying one times ten to the minus two.Now i can solve for the negative logs, one times ten to the minus three gives me three,.
One times ten to the minus two gives me two.And so this was an h plus concentration, my ph would be somewhere between two and three.This is where you wanna be careful.Four point five seems like the halfway between looks like four and five but it's not going to be the halfway between my phs.This is where you have to make a decision, check your mcat choices, if you see only one value with the ph two and three pick that answer and save your time.But if you have multiple values you need to.
Zero in a little more we can take this trick a step further.What you want to understand moving forward is that a logarithmic scale is going to go ten to a hundred thousand so we'd start small and then it sky rockets so the numbers are going to follow a similar pattern.In addition to name the values between one and ten, it helps to recognize if not to memorize what the negative log values will be if your coefficient is a three, a five, a seven or an eight because then you can always extract.
Like the numbers in between.I'll show you the calculator values and then i'll show you the numbers that you want to study.The negative log of one times ten to the minus three is three we already know that.But as we increase from one times ten to the minus three all the way to ten times ten to the minus three, we're moving closer and closer to two.So as your coefficient goes up, your ph, your pka or the number that we derive is going to go down.Three times ten to the minus three in the.
Calculator is equal to two point fifty three.What i want you to recognize is three times any power is going to give me a number point five.Five times ten to the minus three on the calculator is two point three, so recognize that if we have a five we get a number point 3.Eight times ten to the minus three is equal to two point one so any number starting with an eight will give a number point one.And obviously if we add in ten times ten to.
The minus three which is the same thing as saying one times ten to the minus two, our answer is going to be two.So here's the pattern to recognize, three starts with the five that's like your halfway point and then we go down three down to one we're at the lower number.In other words, for the quicker version, if you're given five times ten to the minus three, we recognize the number is near three but because it's a five another one we have to go down and the answer will be two point something.In this case two point three.
So let's go back to our initial example, we're trying to solve two point three times ten to the minus four.First we want to find the range and the range will be, this is my lowest number because i round two point three down to one.One times ten to the minus four is four.Rounding it up to ten, two point three becomes ten times ten to the minus four or one times ten to the minus three giving me three.So we know the poh is going to be between three and four.Remember the trick when we.
Use three times ten to the minus three and it was two point five three in this case, two point three is very close to three so the answer should be very close to point five.But we have to take the smaller number, it won't be four point five, it will be something like three point five because we know our poh range has to be between three and four.Three point five in the mcat will be close enough and then we do fourteen minus three point five which is our poh and that gives us an answer of ten point five for our ph.
Punching this example into the calculator gave me an answer of ten point three six which on the mcat is close enough.Be sure to join me in the next tutorial where i show you a similar shortcut how to solve antilogs or when you're given a ph poh or pka and have to find the concentration or the ka value.Are you stuck on a specific mcat topic i offer private online tutoring where i focus on your needs to strengthen your individual weaknesses.Tutoring details can be found using the link below or by visiting my website leah4scimcattutor.
Are you overwhelmed by the sheer volume of information required for the mcat are you worried that lack of a proper study plan and low mcat score will prevent you from getting into medical school my new ebook the mcat exam strategy is 6week guide to crushing the mcat will help you formulate a concrete study plan by helping you figure out where you stand now, identify your goals and figure out what it takes to reach them and it's yours free when you sign up for my email newsletter at mcatexamstrategy.Com.By signing up for.
MCAT Math Vid 9 Antilogs in pH and pKa Without A Calculator
Leah here from leah4scimcat and in this tutorial, i'll show you how to solve mcat style antilogs questions without a calculator.This tutorial picks up from my last tutorial where i show you how to solve logarithm based questions and you can find this tutorial alongwith my entire series on solving mcat math without a calculator by visiting my website leah4scimcatmath.In the last tutorial i showed you a trick on how to find a ph, poh or pka value when given a concentration or ka.The trick showed you that when you have a number times ten to a.
Negative power, that power becomes your pka, your ph or your poh.But what if now you are faced with a question where the actual ph, poh or pka value is given and you're ask to find the concentration or the ka for example you maybe given a question that says 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.I'll cover the science portion of this question in my chemistry tutorials at leah4scimcatchemistry but for this tutorial let focus just on the math.Since we're dealing with a buffer we'll use.
The hendersonhasselbalch equation which says that ph is equal to pka plus the log of conjugate base over acid.You'll also see this written as a minus over ha.Even though we have equal moles of acid and conjugate base or fiftyfifty, whatever number we have for conjugate base is the number for acid and that means we have a ratio of some number over itself or one.The log of one is zero and that means this entire portion of the equation drops out telling me that the ph is equal to the pka.Knowing.
That the ph is equal to 4.19 equals the pka we know the pka is also equals to 4.19.But how do we use this to find the ka value of this acid 4.19 is not a clean and easy number to calculate so let's break it down the first thing you want to do is check how close your answer choices are to each other to see how much you can simplify and how quickly you can come up with the answer.Here's the equation we'll use.If pka is equal to negative.
Log of ka pka log ka, since log stands for log base ten, to solve for ka we have to have ten to the power of negative log to cancel out and that means we need ten to the power of negative pka.So the ka value is equal to ten to the minus pka which is equal to ten to the minus four point one nine ka 10pka 104.19.A nice and clean number like four would give us a ka value of one times ten to the minus.
Four.But we also have to account for that 4.19 so we don't know we're looking for the number close to one times ten to the minus four.If this is not enough to isolate your answer, you then want to find the range where your ka will fall out.We'll take the number 4.19 and round it down to 4 and up to 5.A pka of 4 has a ka of one times ten to the minus four, a pka of 5 has a ka of one times ten to the minus five.That.
Means the number we're looking for is somewhere in this range.But if this is still not enough, then you wanna go back to the trick where i showed you how to recognize the different numbers that give you different ranges.In review, if we have a number point one we get an eight time ten to the minus x.And i put x instead of the number because if we have 4.19 our exponent will be a number times ten to the minus five.So if we had 4.1 it will.
Be eight times ten to the minus five.A number point three will be five times ten to the minus that power.In this case, if we have 4.19, let's round that to 4.2, remember on the mcat you are allowed to round because it will be close enough.If point one gives me an eight and point five gives me a five then our answer has to be somewhere between eight and five so all you have to recognize is that the number is somewhere between five and eight.So it'll be five times ten to the minus five to eight times ten to the minus.
Five.Even if we haven't narrowed in on a specific number, for the mcat this is close enough.In fact, punching ten to the negative four point one nine in the calculator i get an answer of 6.46 times ten to the minus five which on the mcat is close enough.If you wanna narrow this down a little more, 4.19 is closer to 4.1 than it is to 4.3 and that means we'll be closer to the 8 than to the 5 as is evident by 6.46.This concludes my tutorial series on mcat math.
Without a calculator.You can find this entire series on my website at leah4scimcatmath.You can find additional mcat tutorials including physics, chemistry, biology and organic chemistry on my website leah4scimcat are you stuck on a specific mcat topic i offer private online tutoring where i focus on your needs to strengthen your individual weaknesses.Tutoring details can be found using the link below or by visiting my website leah4scimcattutor.Are you overwhelmed by the sheer volume of information required for the mcat are you worried that lack of a proper study plan and.
Low mcat score will prevent you from getting into medical school my new ebook the mcat exam strategy is 6week guide to crushing the mcat will help you formulate a concrete study plan by helping you figure out where you stand now, identify your goals and figure out what it takes to reach them and it's yours free when you sign up for my email newsletter at mcatexamstrategy.By signing up for my email newsletter, you'll also be the first to know when i have new tutorials, mcat study guide cheat sheets tips.
Calculating The PH Of Acids Acids Bases Tutorial
Calculating the ph of acids acids bases tutorial,How do you calculate the ph of acids and bases calculating the ph of acids this tutorial shows you how to calculate the ph of an acid and base it explains. Titration practical and calculation naoh and hcl,This tutorial with the help of flash animations shows and explains how you can determine the concentration of a sodium hydroxide solution using a standard. Alkaline diet the simple alkaline diet to lose weight naturally stay healthy,Alkaline diet the simple alkaline diet to lose weight naturally stay healthy so what exactly is the alkaline diet program if its not any of those what is it.
Calculating ph poh h h3o oh of acids and bases practice,This tutorial on acids and bases shows you how to calculate the ph poh h oh of acid and base solutions acids and bases can be measured by their. Mcat math vid 9 antilogs in ph and pka without a calculator,Leah4scimcat presents mcat math without a calculator tutorial 9 solving mcat antilog calculations without a calculator is your mcat just around. Mcat math vid 8 logarithms and negative logs in ph and pka without a calculator,Leah4scimcat presents mcat math without a calculator tutorial 8 solving mcat logarithm calculations without a calculator is your mcat just.
Calculating ph poh h oh acids bases clear simple,Acids bases this tutorial shows you how to calculate the poh of a solution when given the oh concentration from the poh you can then solve for the ph of.
Ph poh of strong acids and bases chemistry khan academy,Deriving the relationship between pkw ph and poh calculating the ph or poh of strong acids and bases created by sal khan watch the next lesson. Buffers introduction calculation of ph of buffers acid base equilibrium,Buffers introduction calculation of ph of buffers acid base equilibrium link to my chemistry pagevinstan a brief introduction into buffers.
PH Testing The Body With PH Test Strips More Accurate Than Litmus Paper
Ph testing the body with ph test strips more accurate than litmus paper,Novadetoxacatalogphteststrips its easy to test the ph of your body and fluids ph with self testing strips for ph levels check urine and. How to calculate needed batteries size or batteries bank size in ampere hours unit,Web site link about nasirtech web site nasirtechau channel nasirtechdotcomdotau faccebook page. How to calculate oxidation numbers introduction,Well learn how to determine the oxidation numbers or oxidation states for a the elements in a chemical compound the oxidation numbers tell us how electrons.
Example calculation ph of a weak acid,More free chemistry help tutorialsnathanoldridgechemistrytutorials here i go through a calculation of the ph of a solution made with a weak. Ph and poh crash course chemistry 30,You can directly support crash course atsubbablecrashcourse subscribe for as little as 0 to keep up with everything were doing also if you. Ph of sulfuric acid,Calculate the ph for a 010m sulfuric acid solution ka1 large and ka2 0012 solved using the graphing calculator.
Ph calculation of an acidic salt,Webpagekentchemistrylinksacidsbasesphacidicsaltshtm this short tutorial shows you how to calculate the ph of an acidic salt when given the. Acids bases and ph,Paul andersen explains ph as the power of hydrogen he explains how increases in the hydronium ion or hydrogen ion concentration can lower the ph and. Stomach acid problems drvipun reddy,First health channel in telugu we have the tutorials on health problems and expert s advise on below concepts please watch it care fully alkaline foods.
Acid Base Equilibria Pt 6 Concentration From PH Calculation
Acid base equilibria pt 6 concentration from ph calculation,Chemistry revision on the move acidbase equilibria revision for your mobile qechrome leicester. The alkaline diet healthy alkaline foods ph balance food chart,For more information please click link herehairizrecommendsacidalkalinediet the diet of our ancestors is completely different from what. Calculating ph for acidbase titrations 1,Chemistry calculating ph at various points on a titration curve titration of a strong acid with a strong basevertical intercept left of equivalence point.
Ph of a weak acid 01 m acetic acid example,Includes the assumption teachers tell you to make how do you find the ph of a weak acid solution this tutorial goes through the whole calculation just fill in. Find the ka of an acid given ph 01 m hypochlorous acid example,This tutorial shows how you can calculate the ka of an acid if youre given the ph of the solution and its concentration of course its pretty straightforward if you. Solving acidbase titration problems,A stepbystep tutorial on solving acidbase titration math problems uses the double mole map method focusing on 4 steps 1 write a balanced equation for the.
How to use borax to raise the ph in your pool how much borax to add,Websiteswimmingpoollearning youtube tutorial index a list of all of my tutorials. Gerd anandakumar p1,First health channel in telugu we have the tutorials on health problems and expert s advise on below concepts please watch it care fully alkaline foods. Food pipe problems dr kiran peddi,First health channel in telugu we have the tutorials on health problems and expert s advise on below concepts please watch it care fully alkaline foods.