what is the [OH-] in a solution that contains 0.225g of NaOH in 0.250 L of solution
To find the concentration of hydroxide ions ([OH-]) in a solution, you need to calculate the moles of NaOH dissolved in the solution.
Step 1: Calculate the molar mass of NaOH.
The molar mass of NaOH is the sum of the atomic masses of sodium (Na), oxygen (O), and hydrogen (H). The atomic masses are:
Na = 22.99 g/mol
O = 16.00 g/mol
H = 1.01 g/mol
Molar mass of NaOH = (1 × Na) + (1 × O) + (1 × H) = (1 × 22.99) + (1 × 16.00) + (1 × 1.01) = 39.00 g/mol
Step 2: Calculate the number of moles of NaOH.
The number of moles can be calculated using the formula:
moles = mass / molar mass
moles of NaOH = 0.225 g / 39.00 g/mol
Step 3: Calculate the molarity of NaOH solution.
Molarity (M) is defined as the number of moles of solute per liter of solution.
Molarity = moles / volume
Molarity of NaOH = moles of NaOH / volume of solution = (0.225 g / 39.00 g/mol) / 0.250 L
Step 4: Calculate the concentration of hydroxide ions ([OH-]).
In a 1:1 ratio, each mole of NaOH dissociates into one mole of hydroxide ions (OH-).
[OH-] = Molarity of NaOH
Therefore, the concentration of hydroxide ions in the solution is equal to the molarity of NaOH, which can be calculated using the formula above.
To find the hydroxide ion concentration ([OH-]) in a solution, we need to know the amount of hydroxide ions present in the solution, as well as the volume of the solution. In this case, we are given that 0.225 grams of NaOH is dissolved in 0.250 liters of solution.
To calculate the hydroxide ion concentration, we need to follow these steps:
Step 1: Convert the mass of NaOH to moles. To do this, we will use the molar mass of NaOH, which is 40.00 g/mol.
Moles of NaOH = Mass of NaOH / Molar mass of NaOH
= 0.225 g / 40.00 g/mol
Step 2: Calculate the molarity of NaOH. Molarity (M) is defined as moles of solute divided by liters of solution.
Molarity of NaOH = Moles of NaOH / Volume of solution
= (0.225 g / 40.00 g/mol) / 0.250 L
Step 3: The hydroxide ion concentration is equal to the molarity of NaOH, as NaOH is a strong base and dissociates completely in water to release hydroxide ions.
[OH-] = Molarity of NaOH
Now, let's calculate the hydroxide ion concentration:
Moles of NaOH = 0.225 g / 40.00 g/mol
= 0.005625 mol
Molarity of NaOH = (0.005625 mol) / 0.250 L
= 0.0225 M
[OH-] = 0.0225 M
Therefore, the hydroxide ion concentration in the given solution is 0.0225 M.
mols NaOH = grams/molar mass
M NaOH = mols/L soln
(OH^-) = M NaOH.