determine the ph of 5 grams KNO3 that is dissolved in 100ml water.KNO3 is produced by mixing .2M KOH and 0.2M HNO3...please help me...pls..
To determine the pH of a solution of KNO3, you need to know the concentration of the solution. In this case, you are given that KNO3 is produced by mixing 0.2M KOH and 0.2M HNO3.
To find the concentration of KNO3, you need to determine the reactant that is limiting. Since both KOH and HNO3 have the same concentration, you can calculate the moles of each reactant and compare them. The balanced chemical equation for the reaction between KOH and HNO3 is as follows:
KOH + HNO3 → KNO3 + H2O
The molar ratios for the reaction are 1:1, meaning one mole of KOH reacts with one mole of HNO3 to produce one mole of KNO3.
First, convert the given data of the volume (100 mL) to liters by dividing by 1000:
Volume of solution = 100 mL ÷ 1000 = 0.1 L
Next, calculate the number of moles for KOH and HNO3.
Moles of KOH = 0.2 M × 0.1 L = 0.02 moles
Moles of HNO3 = 0.2 M × 0.1 L = 0.02 moles
Since the moles of KOH and HNO3 are equal, neither is in excess, and both will be completely consumed in the reaction. Therefore, the concentration of KNO3 will also be 0.2M.
Now, to determine the pH of the KNO3 solution, you need to know the dissociation of KNO3. KNO3 fully dissociates into K+ and NO3- ions. Since KNO3 is a neutral salt, it does not directly contribute to the pH of the solution.
To find the pH, you need to determine the effect of the water on the pH. Water partially dissociates into H+ and OH- ions.
H2O ⇌ H+ + OH-
Since KNO3 is a neutral salt and does not contribute to the H+ or OH- concentration, the concentration of H+ in the solution will depend only on the water. Since the solution is not acidic or basic, we can consider it neutral.
Therefore, in a neutral solution, the concentration of H+ equals the concentration of OH-. Since pure water is neutral, its concentration of H+ and OH- ions are equal, resulting in a concentration of 10^-7 M for both.
Thus, the pH of the KNO3 solution is 7.
To determine the pH of a solution, we need to understand the dissociation properties of the components involved.
KNO3 is a salt that dissociates completely in water, meaning it breaks up into its respective ions: K+ and NO3-. The K+ ion does not affect the pH of the solution, so we can disregard it for pH calculations.
HNO3 is a strong acid that also fully dissociates in water, yielding H+ and NO3- ions.
First, let's calculate the concentration of H+ ions in the solution after mixing 0.2M KOH and 0.2M HNO3. Since KOH and HNO3 react in a 1:1 ratio, they will neutralize each other completely.
The concentration of H+ ions contributed by 0.2M HNO3 is 0.2M.
Since H+ and OH- ions react in a 1:1 ratio to form water, the concentration of OH- ions contributed by 0.2M KOH is also 0.2M.
Now, we have both H+ and OH- ions in the solution. Since they react to form water, they will neutralize each other. The amount of OH- ions is equal to the amount of H+ ions, resulting in a neutral pH of 7.
However, you mentioned that 5 grams of KNO3 is dissolved in 100 ml of water. To determine the pH, we need to consider the additional KNO3 in the solution.
The molar mass of KNO3 is approximately 101 g/mol.
To find the molarity of KNO3 in the solution, divide 5 grams by the molar mass of KNO3:
(5 g) / (101 g/mol) ≈ 0.0495 mol
Now, calculate the concentration (molarity) of KNO3:
0.0495 mol / (0.1 L) = 0.495 M
Since KNO3 fully dissociates in water, the concentration of NO3- ions is also 0.495 M.
Since NO3- ions do not affect the pH, we can focus on the H+ ion concentration.
Since HNO3 is a strong acid and dissociates completely, the concentration (molarity) of H+ ions is still 0.2 M.
Now, calculate the pH of the solution. The pH is defined as the negative logarithm (base 10) of the H+ ion concentration:
pH = -log(0.2) ≈ 0.69897
So, when 5 grams of KNO3 are dissolved in 100 ml of water, the pH of the resulting solution is approximately 0.69897 or around 0.7.