00:01
Hi, so for this problem we're going to have a solution that contains a mixture of 30 milliliters of 0 .3 molar nitric acid, which is a strong acid, that means that it dissociates completely in water, with 60 milliliters of a 0 .8 molar solution of a strong base, that is barium oh2.
00:26
Again, this means that this, as being a strong base, is going to dissociate completely in water.
00:33
So the first thing that we need to do is find the concentration of h +, and the concentration of oh-, that we are adding, in order to know which one is going to react, because at the end of the day nitric acid is going to react with the oh-, right? the hydronium ion generated by the acid reacts with the oh - of the base.
01:00
So in order to do that, let's calculate the amount of mole of h +, that we're going to have, that is simply 30 milliliters, which in liters is 30 times 10 to the minus 3 liters, multiplied by 0 .3 molar, and the amount of mole of oh-, in this case, since one equivalent, or one mole of barium hydroxide, is going to be equal to two moles of oh-, because when we did the solution of this compound in water, this is going to generate barium 2 +, plus 2oh-, right? so the amount of mole of oh-, it's going to be two times the amount of mole of barium hydroxide that we added, that is 16 times 10 to the minus 3 liters, times the concentration of that hydroxide.
02:06
With this, we can find the amount of mole of each of them, so it is going to be 9 times 10 to the minus 3 mole of h +, or h3o +, however you want to write it down, and on the other side, 0 .096 mole of oh-.
02:40
So which one is in larger quantity? of course the oh-, so n of oh - final, it is going to be the initial value, minus the amount that reacts, and the that reacts is the same as the amount of h +, that we added, minus 9 times 10 to the minus 3 mole of h+.
03:10
This gives us a final amount of 8 .7 times 10 to the minus 2 mole of oh-...