Calculate the molarity of 500. mL of solution containing 21.1 g of potassium iodide
grrg
21.1 g KI is how many moles.
moles = grams/molar mass = ??
Then M = moles/L. Substitute for mols and L and solve for M.
To calculate the molarity of a solution, you need to determine the number of moles of solute and the volume of the solution. Let's follow these steps to find the molarity of the potassium iodide solution:
1. Convert the mass of potassium iodide (KI) to moles:
- The molar mass of KI is 166 g/mol (39 g/mol for potassium (K) and 127 g/mol for iodine (I)).
- Use the formula: moles = mass / molar mass
moles of KI = 21.1 g / 166 g/mol
2. Convert the volume of the solution to liters:
- The volume is given as 500 mL. Since molarity is in terms of liters, we need to convert mL to L.
- 1 L = 1000 mL, so 500 mL is equal to 0.5 L.
3. Calculate the molarity (M) of the potassium iodide solution:
- Molarity is defined as the number of moles of solute divided by the volume of the solution in liters.
- Molarity (M) = moles of KI / volume of solution (in L)
Molarity = moles of KI / 0.5 L
Now, let's calculate the molarity:
moles of KI = 21.1 g / 166 g/mol ≈ 0.127 moles
Molarity = 0.127 moles / 0.5 L ≈ 0.254 M
Therefore, the molarity of the potassium iodide solution is approximately 0.254 M.
To calculate the molarity of a solution, you need to know the moles of solute and the volume of the solution.
Step 1: Calculate the moles of potassium iodide (KI).
Moles = mass / molar mass
The molar mass of KI is the sum of the atomic masses of potassium (K) and iodine (I). From the periodic table, the atomic mass of K is approximately 39.1 g/mol, and the atomic mass of I is approximately 126.9 g/mol.
Molar mass of KI = 39.1 + 126.9 = 166 g/mol
Moles of KI = 21.1 g / 166 g/mol ≈ 0.127 moles
Step 2: Convert the volume of the solution to liters.
Volume = 500 mL = 500/1000 = 0.5 L
Step 3: Calculate the molarity.
Molarity (M) = moles / volume
Molarity = 0.127 moles / 0.5 L = 0.254 M
Therefore, the molarity of the solution is 0.254 M.