How many grams of KNO3 are needed to make 450 mL of a solution that is to contain 5.50 mg/mL of potassium ion?
Calculate the molarity of the solution.
______g
______M
i honestly don't know where to start, but i know that M=mol/L will be involved somewhere...
Please help...
To solve this problem, we will need to calculate the amount of KNO3 in grams and then determine the molarity of the solution.
Step 1: Calculate the amount of potassium ion needed in mg.
Given that the desired concentration of potassium ion is 5.50 mg/mL and the volume of the solution is 450 mL, we can calculate the total amount of potassium ion needed:
Amount of potassium ion = concentration × volume
Amount of potassium ion = 5.50 mg/mL × 450 mL = 2475 mg
Step 2: Convert the amount of potassium ion from mg to grams.
Since the molar mass of potassium ion (K+) is 39.10 g/mol, we can convert the amount of potassium ion from mg to grams:
Amount of potassium ion in grams = 2475 mg × (1 g / 1000 mg) = 2.475 g
Step 3: Calculate the amount of KNO3 needed.
Since KNO3 dissociates into one potassium ion and one nitrate ion (NO3-) in solution, the amount of KNO3 needed will be the same as the amount of potassium ion calculated in Step 2:
Amount of KNO3 needed = 2.475 g
Therefore, the number of grams of KNO3 needed to make the solution is 2.475 g.
Step 4: Calculate the molarity of the solution.
The molarity of a solution is calculated using the formula:
Molarity (M) = moles of solute / volume of solution in L
Since we have the amount of KNO3 in grams, we need to convert it to moles using its molar mass (101.10 g/mol):
Moles of KNO3 = 2.475 g / 101.10 g/mol = 0.02446 mol
Now we can calculate the molarity using the volume of the solution in liters:
Molarity = 0.02446 mol / 0.450 L = 0.0544 M
Therefore, the molarity of the solution is 0.0544 M.
To calculate the number of grams of potassium nitrate (KNO3) needed to make the solution, you need to use the following formula:
grams = volume (in liters) × concentration (in mol/L) × molar mass (in g/mol)
First, let's calculate the number of moles of potassium ion (K+) needed in the solution:
moles = volume (in liters) × concentration (in mol/L)
Given:
Volume of the solution = 450 mL = 450/1000 L = 0.450 L
Concentration of potassium ion = 5.50 mg/mL = 5.50 × 10^(-3) g/mL = 5.50 × 10^(-3) g/0.450 L = 12.22 mol/L (approximately)
Now, we need to calculate the molar mass of KNO3, which includes the molar masses of potassium (K), nitrogen (N), and oxygen (O):
Molar mass of K = 39.10 g/mol
Molar mass of N = 14.01 g/mol
Molar mass of O = 16.00 g/mol
Molar mass of KNO3 = (1 × molar mass of K) + (1 × molar mass of N) + (3 × molar mass of O)
Molar mass of KNO3 = (1 × 39.10 g/mol) + (1 × 14.01 g/mol) + (3 × 16.00 g/mol)
Molar mass of KNO3 = 101.10 g/mol
Now, we can calculate the grams of KNO3 using the formula:
grams = volume (in liters) × concentration (in mol/L) × molar mass (in g/mol)
grams = 0.450 L × 12.22 mol/L × 101.10 g/mol
grams = 55.14 g (approximately)
Therefore, you will need approximately 55.14 grams of KNO3 to make 450 mL of the solution.
Next, let's calculate the molarity of the solution:
Molarity is defined as the number of moles of solute (KNO3) divided by the volume of the solution in liters:
Molarity (M) = moles of solute / volume of solution (in liters)
Given:
moles of KNO3 = grams of KNO3 / molar mass of KNO3
moles of KNO3 = 55.14 g / 101.10 g/mol (approximately)
Now, plug in the value for moles of KNO3 and the volume of solution to calculate the molarity:
Molarity (M) = (55.14 g / 101.10 g/mol) / 0.450 L
Molarity (M) = 1.21 M (approximately)
Therefore, the molarity of the solution is approximately 1.21 M.
You want 5.50 mg/mL and you want 450 mL. So mg needed = 5.50 mg/mL x 450 = ??mg
Convert that to grams. Then convert that many g K^+ to KNO3.
g KNO3 = g K^+ needed x (molar mass KNO3/atomic mass K^+) = ??
For M, convert grams KNO3 to moles. moles = grams/molar mass, then M = moles/L.