How do i find the PH and pOH of 12.5ml of 15.8M HNO3 added to 400ml of 0.57M KOH
HNO3 + KOH ==> KNO3 + H2O
millimols HNO3 = M x mL = approx 200 but this is just an estimate.
mmols KOH - 0.57 x 400 = approx 228.
So HNO3 is the limiting reagent; all of the HNO3 will be used and 28 mmols KOH will be left over. So the pH will be determined by the excess KOH.
M KOH = mmols/mL = approx 28/412.5 = ?, then pH + pOH = pKw = 14 and solve for pH.
Remember to recompute all of the numbers since I've estimated them.
To find the pH and pOH of the solution resulting from the reaction of 12.5 mL of 15.8 M HNO3 with 400 mL of 0.57 M KOH, you will need to follow several steps. Let's break it down:
Step 1: Determine the number of moles of HNO3 and KOH
To find the number of moles, you can use the equation:
Moles = Concentration x Volume (in liters)
For HNO3:
Moles of HNO3 = 15.8 M x 0.0125 L
For KOH:
Moles of KOH = 0.57 M x 0.400 L
Step 2: Determine the limiting reactant (the reactant that gets completely used up)
To determine which reactant is limiting, compare the mole ratio of HNO3 to KOH. The balanced equation for the reaction between HNO3 and KOH is:
HNO3 + KOH -> KNO3 + H2O
The mole ratio is 1 mol HNO3 to 1 mol KOH. Therefore, the reactant with the smaller number of moles is the limiting reactant.
Step 3: Calculate the excess moles of the excess reactant (if any)
If one of the reactants is in excess, calculate the excess moles by subtracting the moles used by the limiting reactant from the moles originally present.
Step 4: Calculate the new concentrations of the ions in the solution
After determining the limiting reactant and any excess moles, you can calculate the new concentrations of the ions in the solution. Since the reaction between HNO3 and KOH results in the formation of KNO3 and H2O, the concentration of K+ and NO3- will increase while the concentration of H+ and OH- will decrease.
Step 5: Calculate the pH and pOH
To calculate the pH and pOH, you need to know the concentrations of H+ and OH-. Since this is a neutralization reaction, the moles of H+ and OH- will be equal, and the pH and pOH will be equal. You can use the equation:
pH = -log[H+]
pOH = -log[OH-]
Step 6: Find the final pH and pOH
Finally, calculate the pH and pOH using the concentrations of H+ and OH- obtained from step 4.
Remember to use the correct units and significant figures throughout the calculations.