Answer:
pH =1 2.84
Explanation:
First we have to start with the <u>reaction</u> between HCl and KOH:
Now <u>for example, we can use a volume of 10 mL of HCl</u>. So, we can calculate the moles using the <u>molarity equation</u>:
![M=\frac{mol}{L}](https://tex.z-dn.net/?f=M%3D%5Cfrac%7Bmol%7D%7BL%7D)
We know that
and we have the concentration of the HCl
, when we plug the values into the equation we got:
![0.282M=\frac{mol}{0.01L}](https://tex.z-dn.net/?f=0.282M%3D%5Cfrac%7Bmol%7D%7B0.01L%7D)
![mol=0.282*0.01](https://tex.z-dn.net/?f=mol%3D0.282%2A0.01%20)
![mol=0.00282](https://tex.z-dn.net/?f=mol%3D0.00282)
We can do the same for the KOH values (
and
).
![0.141M=\frac{mol}{0.05L}](https://tex.z-dn.net/?f=0.141M%3D%5Cfrac%7Bmol%7D%7B0.05L%7D)
![mol=0.141*0.05](https://tex.z-dn.net/?f=mol%3D0.141%2A0.05%20)
![mol=0.00705](https://tex.z-dn.net/?f=mol%3D0.00705)
So, we have so far <u>0.00282 mol of HCl</u> and <u>0.00705 mol of KOH</u>. If we check the reaction we have a <u>molar ratio 1:1</u>, therefore if we have 0.00282 mol of HCl we will need 0.00282 mol of KOH, so we will have an <u>excess of KOH</u>. This excess can be calculated if we <u>substract</u> the amount of moles:
![0.00705-0.00282=0.00423mol~of~KOH](https://tex.z-dn.net/?f=0.00705-0.00282%3D0.00423mol~of~KOH)
Now, if we want to calculate the pH value we will need a <u>concentration</u>, in this case KOH is in excess, so we have to calculate the <u>concentration of KOH</u>. For this, we already have the moles of KOH that remains left, now we need the <u>total volume</u>:
![60mL=0.06L](https://tex.z-dn.net/?f=60mL%3D0.06L)
Now we can calculate the concentration:
![M=\frac{0.00423mol}{0.06L}](https://tex.z-dn.net/?f=M%3D%5Cfrac%7B0.00423mol%7D%7B0.06L%7D)
![M=0.0705](https://tex.z-dn.net/?f=M%3D0.0705)
Now, we can <u>calculate the pOH</u> (to calculate the pH), so:
Now we can <u>calculate the pH value</u>: