00:01
All right.
00:03
Hello everyone.
00:04
Okay.
00:05
So today we have this reaction of arsenic trisulfide reacting with nitric acid and water.
00:17
All right.
00:17
To form, i guess this is arsenic acid.
00:26
Then we have nitrogen oxide.
00:30
And then finally we have so far.
00:31
So for solid, pure so forth.
00:37
All right.
00:38
Anyways, okay.
00:39
Later, you can add silver nitrate to arsenic acid, right, to form a precipitate, all right? of the formula, i guess, silver arsenate or something.
01:00
So i'm not sure if it's silver arsenate or silver arsenite or silver arsenite.
01:03
Something because the subscripts are actually unknown all right however this solid that we actually form right by adding silver nitrate to arsenic acid all right is 16 .199 % all right arsenic and 969 .9 .64 percent silver all right that would come in handy all right okay now um since there's only three elements present here right one two and three right silver arsenic and oxygen we can definitely say that the amount of oxygen present here would simply be 100 percent minus this two percentage yes so let's try to figure it out and then you know maybe that would help us in the answer later.
02:05
All right.
02:05
So, okay, so we'll start off with 100%, right, minus.
02:12
Okay, so we're going to subtract first the amount of arsenic present, which is 16 .199.
02:19
All right, and then we're going to remove the amount of silver present, which is 69 .964.
02:30
69 .964 giving us now 13 .87 % oxygen.
02:38
So we have about 13 .837 % oxygen.
02:43
All right.
02:44
That should be pretty much, you know, this composition by mass.
02:48
All right.
02:48
So given this problem, the first question is, all right, to determine the oxidation numbers, right, of arsenic, right, in this reaction.
03:00
All right.
03:02
Sulfur.
03:04
Right.
03:04
Sulfur.
03:07
All right.
03:08
In this reaction.
03:09
All right.
03:10
Nitrogen in this reaction.
03:13
All right.
03:13
So you need to figure out the oxidation numbers.
03:15
Okay, cool.
03:16
All right.
03:17
And then the second one is to figure out the proper formula for the silver arsenic, arsenate or silver arsenite.
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In short, figure out what's x and y here.
03:31
So i've already looked up the molecular weights of.
03:34
Silver arsenic and oxygen they are 187 .862 grams per mole 74 .9216 grams per mole and 15 .999 999 grams per mole respectively so definitely those will be important later on.
03:52
Alright so first the thing we're going to figure out would be the oxidation numbers of arsenic so for n nitrogen in the reaction earlier.
04:03
All right.
04:05
So we'll start off all right with arsenic and sulfur all right so from the reaction we see that all right um arsenic and sulfur are in this um reaction right here all right so that's arsenic two and sulfur three all right all right so um both arsenic and um sulfur are non -metals so they should form a covalent one so the proper name for this one would be diarcinic trisulfide all right now because sulfur belongs in group 6a right so automatically we should know that sulfur right would have an oxidation number of negative 2 all right okay so now the thing is okay the thing is what would be the oxidation number four arsenic.
05:08
So now since this one is a neutral compound, it has no extra charge, then the total charges present here should be equal to zero.
05:21
Okay, so since we don't know what the charge of arsenic is, we'll say arsenic has a charge of x.
05:28
It's assumed to be, of course, positive because sulfur has the negative charge.
05:32
Soul 4 has a negative 2 charge so therefore since we have two arsenic atoms in the diarcinic trisulfide compound or molecule all right so there should be a total of positive 2x charge for that right and then we have 3 sulfur atoms in that molecule so that would be it would have a total charge of 3 times negative 2 and this should be equal to 0 because it is a neutral compound so if we continue solving this one we have 2x 3 times negative 2 is negative 6 alright so we're going to continue solving this one i'm going to add 6 to both sides right we have 2x equal to 6 divide everything by 2 and so we have x is equal to positive 3 so therefore the charge of arsenic and diarciniclyosophyte is positive 3.
06:43
All right, okay, cool.
06:45
Now we have that.
06:46
So the last thing for our first question, we will we determine the oxidation number of nitrogen, right, in the nitric acid.
06:56
All right, so nitric acid, all right, has a formula of hn -o -3, h -n -3.
07:08
So from here, right, you can definitely say that, okay, hydrogen has a positive 1 charge, right? because it's a group 1a.
07:23
Oxygen, right, has a charge of negative 2.
07:28
All right, so since we don't know what the charge of nitrogen is, we'll say it's x.
07:35
All right, so now we're going to put in, we're going to like add all the total charge here, and it should, of course, be equal to zero.
07:42
So we start with hydrogen, which only one of it...