Okay, previously I have explained the expression of concentration for percentage. Okay, percentage weight per weight, weight per volume and volume per volume. Now the example of equation under the percentage weight per weight. Okay, so we look at the example. Calculate the molarity of the following.
acids. Okay, given percentage 70% weight per weight per chloride acid and density 1.67 gram per ml. Okay, so the question is calculate the molarity.
Okay, given the percentage, so how we want to find the molarity of this? solution okay so actually you have to convert okay this one is a chemical or perchloric acid in a bottle chemical bottle okay usually given in percentage okay so you have to convert to molarity another expression of concentration okay for example the unit is mol per liter, we use mol per liter. So this is also concentration, molarity also concentration.
So we convert the unit concentration week per week to unit concentration of molarity. So how to get the answer? How about the solution? so i show you the technique okay given percentage weight per weight okay here i show you uh the using of unit cancellation of unit to get the desired unit of molarity okay we want to get the unit of molarity so from gram per gram i show you the unit first gram per gram times What element here to get the unit of mole per liter here?
When you look here gram per gram to get mole per liter, so you have to get another species here with the unit. Okay, so this is mole. So what is related with mole?
here okay even does not give an equation you have to find it okay that is a molar mass k which is gram per mole so when mole is uh in the upper pipe okay you just uh put here mole per gram so we can cancel unit gram now mole per gram convert to mole per liter okay So we want to cancel unit gram-fuel with the loop given information is density. Okay, so you put the unit density gram per ml. So we can cancel unit gram and gram-fuel.
Okay, now you get mole per ml. How to change mole per ml to mole per liter? more you will get so now change ml to little so what have uh what species you have to put here okay so you want to cancel a unit ml to get little okay so here is a ml and little conversion unit milliliter and meter so you can cancel unit ml and then you will get our desired unit mole per liter all right this is the technique how to get the molarity from a concentration of a chemical usually acid or base concentrated okay and then you can put the value here okay you look at we look at the solution Okay, so from percentage weight per weight using density, cancel unit gram using conversion unit ml and liter.
So we can cancel unit ml, get the liter, then times with the molar mass. Okay, so you can cancel unit gram. So 70% means that 70 per 100. gram put the unit density 1.67 over 1 ml time commercial unit 1000 ml over 1 liter times molar mass okay so now we have to put mole on the upper part okay actually the molar mass is 100.5 gram per mole okay so when we put mole on top it will be 1 mole okay over 100.5 5 gram okay put the mole on upper pipe okay so you will get the molarity 11.63 mol per liter okay same with this example okay for next explain how to prepare the following solution in lab 500 ml of 2 molar sulfur acid from commercial reagent 90% purity specific given specific gravity 1.84 so remember the notes about preparation of solution this is question preparation of solution so you have to calculate and also give sentence on how to prepare the solution okay but you have to remember this question from the raw material solid or liquid commercial reagent okay so if here Means that how to prepare the following solution?
We want to prepare 5 in polymeric plus 500 ml, okay, 2 molar sulfuric acid, okay, from 90% of weight per weight purity, okay, from water chemical here. So, means that from... concentrated solution of acid you want to prepare slightly diluted solution okay so it is a from liquid commercial reagent okay then if from liquid okay you have to find the molarity first molarity of concentrated acid okay means that you convert from percentage to molarity okay and then second calculation how much the volume need to transfer from concentrated okay to put in volumetric plus 500 ml okay and then you prepare a dilute solution okay dilute with this water and then shake okay that one is the sentence so for uh preparation of solution from liquid commercial reagent find the molarity of concentrated acid and then the volume need to transfer from concentrated to form diluted acid solution okay by using this formula okay dilution right so we look at the solution is same like before the technique okay using a cancellation unit and the conversion unit density and molar mass to get molarity all right and then you get the molarity of concentrated acid from concentration percentage Okay next.
okay you have already get the molarity molarity concentrated here molarity diluted you know to molar and volume diluted so find volume for concentrated using this formula all right so you get 59.2 ml okay remember this is a solution preparation uh the question of preparation of solution so need to have a sentence okay measure and transfer 59.2 ml from uh concentrated acid to 500 ml volumetric flux is stated in solution and then dilute with this water until calibration mark and shake upside now it's like you uh do your you prepare standard solution in lab okay right next is question under weight per volume percentage so briefly explain how to prepare the following solution okay same also you want to prepare the solution Using 1 liter volumetric flask, okay, so given 10.5 percentage weight per volume equals, okay, proper norm. So, from the formula percentage weight per volume, okay, okay, and then you can find the mass of solution. So, 105 gram, okay. needed to have a sentence so weight 105 gram of reagent and then dissolve with small amount of water transfer to 1 liter volumetric flask dilute with water until calibration mark and shake upside down to prepare standard solution we must use volumetric flask to get the accurate volume okay next is another expression of concentration okay we have five per thousand five per million and five per billion okay usually you are using this expression of concentration to for dilute concentration okay for example you want to study the pollution area or water quality so the content of compound in that sample okay so if part per thousand means that exponent three okay thousand exponent three part per million exponent six okay or number of part of a substance present in one million part okay and then part per billion exponent nine okay so example one ppm is uh one million okay exponent six means that we have one gram of substance in one million gram of silver okay so this is the okay uh show the express expression unit of concentration part per thousand part per million part per billion in terms of percentage width per weight volume per volume and weight per volume okay so if you look here a part per thousand, part per million and part per billion.
Okay, we continue. So, when we look at the expression part per thousand, part per million and part per billion, okay, in terms of weight per weight, volume per volume or weight per volume. So, if part per thousand in terms of weight per weight, So the unit that we can use is Here, gram per gram exponent 3. Okay, so 4 parts per thousand, the factor is exponent 3, 4000. So, if the terms if width per width, so means that the unit for PPT in terms width per width is gram per gram, we follow the terms, okay, and times width factor, right?
If... part per thousand under volume per volume okay so we use unit is a ml per ml time factor time exponent 3 if part per thousand for terms weight per volume okay so the unit is gram per ml time factor exponent 3 okay so when we look for the column on the first line here using the unit from the terms okay same with bm okay then we look if 5 a million in terms of weight per volume so the unit is gram per m l time factor exponent six okay if bpb under weight per weight okay gram per gram time that's volume nine right but usually for ppm under terms weight per volume another unit that we always use is milligram per liter okay so under this column so the unit is equal okay for part per thousand underweight per weight unit is gram per gram exponent three or you can use unit milligram per gram okay equal also with the gram per kilogram okay so question for example calculate weight per volume in ppm of sodium in solution containing 2.5 milligram of sodium ion in 500 ml solution so remember if ppm in terms of weight per volume what is the unit okay so if the unit is gram per ml time factor exponent six or another unit is milligram per liter okay so if you use milligram per liter 2.5 milligram solute divided by volume of solution change to liter okay you get 5 ppm or if we use gram per mL exponent 6 okay just put the mass of analyte of solute okay in gram okay divided by volume of solution in mL times exponent 6 if you use the basic unit you have to times with factor so you will get 5 ppm okay for analysis cadmium in water give value 1.2 5 per billion in terms with per volume so what is the mass content in one liter water so remember if this question you have to know what per billion in what terms And then determine the unit. So the unit is gram per ml times exponent 9. If we use the basic unit under weight per volume, gram per ml, don't forget to times with factor.
So given volume of solution, change to ml and then we will get the mass. okay next question determine the part per million of ferrous iron in a solution known to be 1.2 times exponent negative 6 molar of solution of molecule iron phosphate with hydrate okay so in this question determine ppm okay of iron from molecule okay so the molecule is molar given molarity okay mole per liter so the patient want to uh you to find ppm of iron okay so first you have to know the okay the unit we have to know the unit this ppm under what terms either weight per weight weight per volume or volume per volume okay in this question that's not given okay the previous question is directly given in terms with per volume for example so how you want to know the unit in what terms you have to know the terms and then you can identify the unit okay so we go back to the information given is molarity of molecule okay so this involves mol and liter okay so it's like per volume volume is unit liter okay so weight per weight is we remove it so either weight per volume or volume per volume and then we look the number of mole okay so actually mole from you get mole and then before you get mole you have to know mass so this is under weight per volume okay ppm so what is the unit mole okay for example when you we use unit milligram per liter okay so now for information from molarity okay you have to convert uh the unit ppm okay where is the unit milligram per liter okay so when we look the below pipe liter is same okay so uh there's no problem now we change to uh from more to milligram okay how okay so to uh to times we to to get milligram before that we have to get gram so the species here now is molecular weight gram per mole then we can cancel unit mole now gram per liter change to milligram per liter okay so here you can use conversion unit okay gram times milligram over gram okay so you will get milligram per liter okay the same technique like before we calculate the molarity so okay so the molarity times molar mass molecule so the answer is 6.019 times exponent negative 4 gram per liter Now we change gram per liter to milligram per liter. So times milligram and gram the conversion unit. Here 1 gram equals to 1000 milligram and then cancel unit gram we will get. milligram per liter 0.6019 milligram per liter or ppm okay but this one 0.0 0.6019 ppm for molecule if for iron ferrous iron Okay, since the equation one mole of molecules equal to three mol of iron okay so 0.6019 ppm times 3 mol of iron so the last answer is 1.806 ppm okay here if you use the unit milligram per liter because ppm in terms weight per volume if you use gram per ml exponent 6 okay another equal unit you will get the same answer also so you convert the mole per liter to gram per ml exponent 6 right here describe the preparation okay from concentration acid to prepare one liter 0.1 molar HCL okay this equation same with previous example under percentage weight per weight okay but remember here from concentrated acid okay given percentage weight per weight to prepare slightly diluted concentration of acid okay so you have to calculate first and then the sentence part okay this is from liquid concentration of acid okay so you have to find molarity and also volume how much volume transfer okay so unit okay gram per gram and so on you have to try by yourself okay because this question is described operation you have to put the sentence okay next conversion of ppm to molarity previous previous question from molarity to ppm right so now ppm to molarity okay the first thing from terms or either ppm ppt or ppb you have to know the terms under what terms weight per weight or weight per volume or volume per volume and then determine the unit okay so 56 ppm the solution containing 56 ppm calculate the molarity of solution okay so now from ppm convert to molarity so there was this one underweight per volume you need is milligram per liter change to molarity okay from milligram per liter two molarity okay so the bottom is the same so just times with conversion unit between milligram and gram so you can cancel unit gram okay and then times with here okay it is because of mol so mol per gram this is molecular weight okay even though Tak diberi dalam soalan, you can find by yourself.
So, dapat mol per liter. Later on, you fill the value.