- WELCOME TO THE VIDEO TUTORIAL
FOR MASS OVER VOLUME SOLUTION CONCENTRATIONS.
SO, MASS OVER VOLUME IS WRITTEN AS M/V OR WEIGHT/VOLUME.
AND SO, THIS IS AN IMPORTANT CONCENTRATION UNIT,
SO REMEMBER THAT IT'S GOING TO BE THE MASS OF THE SOLUTE
OVER THE VOLUME OF THE SOLUTION.
AND SO MASS OVER VOLUME,
THERE ARE NOT A LOT OF RULES HERE.
WE CAN HAVE ANY MASS UNIT AND ANY VOLUME UNIT.
AND THE POWER HERE IS THAT LETS US KNOW THE RELATIONSHIP
BETWEEN THE SOLUTE AND THE OVERALL SOLUTION.
SO, LET'S SEE IF YOU GUYS ARE GETTING THIS.
WHICH SOLUTION IS THE MOST CONCENTRATED? OKAY?
SO, WE HAVE THE SAME SOLUTE AND SOLVENT.
SO, IF WE LOOK HERE,
IF WE HAVE TWO GRAMS
OF SOLUTE AND TWENTY-FIVE MILS OF SOLUTION.
WE WOULD PUNCH THAT INTO OUR CALCULATOR
AND WE WOULD SEE THAT WE WOULD HAVE 0.08 G/ML.
SO, WE WOULD--
THIS WOULD BE A MASS OVER VOLUME CONCENTRATION
BECAUSE WE HAVE A MASS UNIT DIVIDED BY A VOLUME UNIT.
LET'S COMPARE THIS TO SOLUTION B.
NOW WE HAVE 25 GRAMS OF SOLUTE
DISSOLVED IN A HUNDRED AND TWENTY MILLILITERS OF SOLUTION.
SO, WE PUNCH THOSE VALUES INTO OUR CALCULATOR,
AND WE SEE THAT THIS SOLUTION HAS A 0.21 G/ML.
SO, WE CAN ALREADY SEE THAT SOLUTION B
HAS A HIGHER CONCENTRATION THAN SOLUTION A. NOW,
LET'S LOOK AT SOLUTION C. WE HAVE 0.5 G DIVIDED BY 25 ML.
OKAY. SO, NOW WE WOULD HAVE 0.02 G/ML.
SO, THE IMPORTANT THING HERE
AS WE COMPARE THE VARIOUS SOLUTIONS,
WE HAVE TO MAKE SURE THAT WE HAVE THE SAME MASS
AND THE SAME VOLUME UNITS TO BE ABLE
TO COMPARE THE CONCENTRATIONS.
NOW, WHEN WE LOOK AT D, WE HAVE 5 G/75 ML.
SO, THAT WOULD BE 0.067
G/ML OR 0.7 G/ML,
IF WE'RE PAYING ATTENTION TO SIG FIGS. OKAY.
SO, SO FAR, NOW WE COULD SEE--
OH, THAT WAS 0.07, OKAY.
SO, SO FAR, SOLUTION B IS THE HIGHEST CONCENTRATION.
AND THEN THIS LAST ONE, 30G IN A 150 ML,
SO WE TAKE 30 DIVIDED BY 150, AND WE GET 0.20 G/ML.
AND FOR SIG FIGS, WE WOULD DROP IT TO THERE, OKAY.
SO, NOW, WE COMPARE THESE RESULTS
AND WE SEE THAT SOLUTION B HAS EVER SO SLIGHTLY
THE HIGHER CONCENTRATION, 0.21 G/ML.
SO, THIS FIRST PRACTICE PROBLEM IS JUST
A VERY STRAIGHTFORWARD WAY THAT WE CALCULATE A CONCENTRATION,
ANY MASS UNIT AND ANY VOLUME UNIT.
IF WE WANT TO COMPARE SOLUTIONS, WE HAVE TO MAKE SURE
THAT OUR MASS AND VOLUME UNITS AGREE.
NOW, LET'S LOOK AT HOW WE CAN USE A MASS
OVER VOLUME CONCENTRATION IN A CALCULATION.
SO, THIS FIRST PRACTICE WAS CALCULATING MASS OVER VOLUME.
THE SECOND PRACTICE PROBLEM IS GOING TO BE
USING MASS OVER VOLUME.
ALL RIGHT.
SO, LET'S LOOK AT THIS QUESTION AND SORT IT ALL OUT.
A SAMPLE OF BLOOD SERUM IS TESTED AND FOUND
TO CONTAIN TESTOSTERONE AT A CONCENTRATION OF-- SO,
THIS PIECE RIGHT HERE, THIS INFORMATION HERE,
THIS IS OUR MASS OVER VOLUME.
SO, IT'S 575 NG OF TESTOSTERONE,
RIGHT, PER 1 ML OF THE BLOOD SERUM.
SO, THE FIRST--
TO MAKE FRIENDS WITH THE CONCENTRATION UNITS,
WE HAVE TO LEARN HOW TO READ THE INFORMATION AND THE QUESTION
AND RECOGNIZE THAT THE NANOGRAMS IS REFERRING TO THE TESTOSTERONE
BECAUSE THAT'S THE SOLUTE,
AND THEN THE MILLILITERS IS REFERRING TO THE BLOOD SERUM
WHICH IS THE SOLUTION. OKAY.
SO, THEN IF WE KEEP GOING WITH THE QUESTION,
HOW MANY GRAMS OF TESTOSTERONE,
SO THAT'S WHAT WE'RE TRYING TO FIGURE OUT,
ARE PRESENT IN 50 ML OF THE SERUM.
ALL RIGHT.
SO, THIS IS WHERE WE START.
SO, ONCE WE HAVE BEEN ABLE TO READ THIS STATEMENT
AND CREATE THIS CONCENTRATION,
IT'S IMPORTANT TO THINK OF IT AS A CONVERSION FACTOR.
SO, THERE ARE 575 NG OF TESTOSTERONE
= 1 ML OF BLOOD SERUM.
NOW, WE CAN GET BUSY AND DO OUR CALCULATION.
ALL RIGHT.
SO, WE HAVE THE BLOOD SERUM AND THERE'S 50 ML.
SO, IT'S VERY IMPORTANT
NOW THAT WE HAVE THE AMOUNT OF BLOOD SERUM,
WE HAVE THE VOLUME UNIT AND WE WANT TO MAKE SURE
THAT WE HAVE THE DESCRIPTOR FOR WHAT THE HECK IT IS,
THIS 50 ML IS.
IT'S THE BLOOD SERUM, IT'S THE SOLUTION.
NOW, WE WANT TO GET TO GRAMS OF TESTOSTERONE.
SO, THIS CONCENTRATION IS THE BRIDGE,
IT CONNECTS THE SERUM,
THE VOLUME OF THE SERUM TO THE MASS OF THE SOLUTE,
THE TESTOSTERONE.
SO, WE HAVE MILLILITERS OF SERUM ON THE TOP,
WE'RE GOING TO HAVE MILLILITERS OF SERUM ON THE BOTTOM,
SO THAT THEY CANCEL OUT.
AND WE KNOW THAT EVERY MILLILITER
OF SERUM HAS 575 NG OF TESTOSTERONE.
SO, WE'VE USED OUR MASS OVER VOLUME CONCENTRATION
TO CONVERT OUT OF SERUM AND INTO TESTOSTERONE,
SO WE CAN CANCEL OUT
THE MILLILITERS OF SERUM, THEY'RE GONE.
SO, NOW WE HAVE NANOGRAMS OF TESTOSTERONE.
ARE WE DONE?
LET'S LOOK BACK AND SEE WHAT THE QUESTION'S ASKING.
IT'S ASKING THE GRAMS OF TESTOSTERONE,
SO WE'RE IN NANOGRAMS,
SO WE'RE GOING TO NEED TO DO A UNIT CONVERSION.
THERE ARE 10 TO THE 9TH NANOGRAM IN A GRAM,
SO HERE'S OUR UNIT CONVERSION.
SO, NOW, WE'VE CANCELLED OUT
THE NANOGRAMS OF TESTOSTERONE AND WE'RE LEFT WITH GRAMS.
SO, WE ARE IN GRAMS OF TESTOSTERONE.
SO, OUR CALCULATION SETUP IS COMPLETE.
NOW, WE GO AHEAD AND PLUG THE VALUES INTO THE CALCULATOR
AND WE GET OUR RESULTS,
AND THE CALCULATOR TELLS US 2.875 X 10
TO THE MINUS 5 G OF TESTOSTERONE.
AND ONCE WE HAVE FINISHED THE CALCULATION,
WE STEP BACK AND WE EVALUATE THE SIG FIGS.
SO, HERE, TRAILING ZEROS WITH A DECIMAL,
THIS WILL BE THREE SIG FIGS.
THREE SIG FIGS HERE, THREE NON-ZEROS.
THE UNIT CONVERSION IS DEFINED SO THAT MEANS IT'S EXACT
OR INFINITE SIG FIGS.
SO, THREE SIG FIGS IS OUR WORST RESULT, OUR WORST DATA.
SO, THAT TELLS US, RIGHT?
SO ONE, TWO MEANS THE QUESTION MARK IS RIGHT HERE.
SO, WE'RE GOING TO ROUND UP SO
IT WOULD BE 2.88 X 10 TO THE MINUS 5 G,
I SHOULD PUT THAT THERE, G OF TESTOSTERONE.
ALL RIGHTY.
SO, THERE ARE--
THERE ARE TWO PRACTICE PROBLEMS
THAT WE'VE WORKED TOGETHER SHOWING HOW TO CALCULATE MASS
OVER VOLUME CONCENTRATIONS
AND THEN HOW TO USE AND INTERPRET MASS,
VOLUME CONCENTRATIONS IN SOLVING CALCULATIONS.
SO, PLEASE TAKE TIME RIGHT NOW TO WORK A COUPLE MORE PROBLEMS
ON YOUR OWN FROM YOUR HOMEWORK,
SO YOU CAN REINFORCE YOUR UNDERSTANDING.