How many grams of KOH must be dissolved in one litre of solution to give it a pH value of 12?
pH + pOH = 14
Solve for pOH.
pOH = -log(OH^-)
Solve for OH^-
How many moles KOH do you need?
moles KOH = M x L = ??
Then moles = grams/molar mass
Solve for grams.
.
PH PoH =14
PoH=14-12=2
PoH=-log[OH]
OH=log~[-2]
OH=O.O1
NOW,
MOLARITY=gm/litre|AT.wt
O.O1=gm/1|57
gm=0.57
hence mass of kOH IS O.57gm.
To determine the number of grams of KOH (potassium hydroxide) needed to dissolve in one liter of solution to achieve a pH value of 12, we need to consider the properties of the solution and perform some calculations.
The pH scale is a logarithmic scale that measures the acidity or basicity (alkalinity) of a solution, with a pH value of 7 considered neutral. Values below 7 indicate acidity, while values above 7 indicate alkalinity.
KOH is a strong base that dissociates completely in water, releasing OH- ions. Thus, to calculate the amount of KOH needed to achieve a specific pH value, we can use the equation:
pOH = 14 - pH
Since pOH = -log[OH-], and KOH fully dissociates into K+ and OH- ions, the concentration of OH- ions is equal to the concentration of KOH in the solution.
To find the concentration of OH- ions, we need to convert the pH value to pOH and then calculate the OH- concentration. Finally, we can convert the concentration of OH- ions to grams of KOH using its molar mass.
Let's go through the calculations step by step:
Step 1: Calculate pOH
pOH = 14 - pH
pOH = 14 - 12
pOH = 2
Step 2: Calculate the concentration of OH- ions
In a neutral solution, the concentration of H+ ions (and OH- ions) is equal to 1 x 10^-7 M.
Using this information, we know that the concentration of OH- ions is also 1 x 10^-7 M.
Step 3: Convert concentration to grams of KOH
The molar mass of KOH is:
K (potassium) = 39.10 g/mol
O (oxygen) = 16.00 g/mol
H (hydrogen) = 1.01 g/mol
KOH = 39.10 + 16.00 + 1.01 = 56.11 g/mol
To convert the OH- ion concentration to grams of KOH, we multiply the concentration by the molar mass:
1 x 10^-7 mol/L * 56.11 g/mol = 5.611 x 10^-6 g/L
Therefore, to achieve a pH value of 12, approximately 5.611 x 10^-6 grams of KOH must be dissolved in one liter of solution.