00:01
Solve the given problem solution contains 1 .12 .5 molar with respect to hf and density is given so we have to calculate more fraction weight percentage of hf malality and malarity so let's start with the weight percentage of hf.
00:27
H .f.
00:30
So first of all, 12 .5 molo of hf means that one kilogram of solvent contains, or actually 1 ,000 grams of water contains 12 .5 moles of hf.
01:02
And also we need to know that we need molecular weight of hf which is 20 .0 grams per mole.
01:14
20 .0 .1 grams per mole.
01:21
So how would we calculate weight percentage of hf? first of all, let's start with a generic formula.
01:28
It equals to mass of hf divided by mass of water plus mass of water plus mass of of hf multiply by 100%, not 1 ,000.
01:46
Okay, so if we've generated the first formula.
01:49
Now let's use the malality.
01:52
If we have 1 ,000 grams of water, then we have 12 .5 mall times 20 .01 gram per mole.
02:11
Of hf.
02:13
So let's calculate this mass.
02:21
It equals to 250 .125 grams.
02:29
So for now we'll just leave all the decimals and round later.
02:33
So now we can calculate the weight percentage of hf.
02:39
So weight percentage of hf equals to this mass of hf divided by 1000 plus mass of each of and it's all multiplied by 100%.
02:57
So let's calculate this number.
03:03
It equals to 20 .0%.
03:14
Okay, we've done question, we've solved question a.
03:17
Now let's move on to question v.
03:21
Oh, sorry, my bet.
03:24
First we've done question b instead of question a.
03:28
Now let's do question a.
03:29
So actually this is answer...