6.2g of NaOH is added to 800ml of water
What is the molarity of the solution?
What is the pH?
mols NaOH = grams/molar mass = ?
Then M = mols/L
(OH^-) = M NaOH
pOH = -log(OH^-)
Then pH + pOH = pKw = 14
To calculate the molarity of the solution, we need to use the formula:
Molarity (M) = Moles of solute / Volume of solution in liters
First, we need to convert the mass of NaOH to moles. The molar mass of NaOH is 22.99 g/mol for Na, 16.00 g/mol for O, and 1.01 g/mol for H, giving us a total molar mass of 39.99 g/mol.
Step 1: Convert grams to moles:
Moles of NaOH = 6.2 g / 39.99 g/mol = 0.155 moles
Next, we need to calculate the volume of the solution in liters. The given volume is 800 mL, so we need to convert it to liters by dividing by 1000.
Step 2: Convert milliliters to liters:
Volume of solution = 800 mL / 1000 mL/L = 0.8 L
Step 3: Calculate the molarity:
Molarity = 0.155 moles / 0.8 L = 0.19375 M
Therefore, the molarity of the NaOH solution is approximately 0.19375 M.
Now, let's move on to calculating the pH of the solution. Since NaOH is a strong base, it dissociates completely in water to form hydroxide ions (OH-) which can affect the pH.
To calculate the pH of a strong base solution, we need to use the formula:
pOH = -log[OH-]
Since NaOH dissociates completely, the concentration of hydroxide ions is equal to the molarity of the NaOH solution.
Step 1: Calculate pOH:
pOH = -log(0.19375) ≈ 0.7127
Step 2: Convert pOH to pH:
pH + pOH = 14
pH = 14 - pOH = 14 - 0.7127 ≈ 13.29
Therefore, the pH of the NaOH solution is approximately 13.29.