Treatment of a 0.2500-g sample of impure potassium chloride with an excess of AgNO3 resulted in the for- mation of 0.2912 g of AgCl. Calculate the percentage of KCl in the sample.
0.0020315*74.5513 = 0.1513
% = 0.1513/0.2500 * 100 =60.52
Well, it looks like we have a "potassium-entially" interesting chemistry problem! Let's calculate the percentage of KCl in the sample, shall we?
To determine the percentage of KCl, we need to calculate the mass of KCl formed and divide it by the initial mass of the sample.
First, let's find the mass of KCl formed. The molar mass of KCl is 74.5513 g/mol (using 39.10 g/mol for K and 35.453 g/mol for Cl).
Using the mass of AgCl formed (0.2912 g), we can calculate the moles of AgCl formed:
moles of AgCl = mass of AgCl / molar mass of AgCl
= 0.2912 g / 143.321 g/mol (molar mass of AgCl)
≈ 0.00203 mol
Since AgNO3 is in excess, we can assume that all the Cl in AgCl comes from KCl. Therefore, the moles of Cl atoms in AgCl are equal to the moles of Cl atoms in KCl, and we can calculate the moles of KCl formed:
moles of KCl = moles of Cl atoms = 0.00203 mol
Finally, we can calculate the mass of KCl formed:
mass of KCl = moles of KCl × molar mass of KCl
= 0.00203 mol × 74.5513 g/mol (molar mass of KCl)
≈ 0.1509 g
To find the percentage of KCl in the sample, we divide the mass of KCl formed by the initial mass of the sample, and multiply by 100%:
percentage of KCl = (mass of KCl / initial mass of sample) × 100%
= (0.1509 g / 0.2500 g) × 100%
≈ 60.36%
So, the percentage of KCl in the sample is approximately 60.36%. "Kudos" to you for working through this problem!
To find the percentage of KCl in the sample, we need to determine the amount of KCl and the total mass of the sample.
1. Calculate the mass of AgCl formed:
Mass of AgCl = 0.2912 g - mass of AgNO3
2. Determine the moles of AgCl formed:
Moles of AgCl = mass of AgCl / molar mass of AgCl
3. Since AgNO3 is in excess, all the Cl in AgCl comes from the KCl in the sample.
Moles of KCl = Moles of Cl in AgCl
4. Determine the moles of KCl sample:
Moles of KCl sample = Moles of KCl
5. Calculate the mass of KCl in the sample:
Mass of KCl in the sample = Moles of KCl sample * molar mass of KCl
6. Calculate the percentage of KCl in the sample:
Percentage of KCl = (Mass of KCl in the sample / Total mass of the sample) * 100
Now we can apply these steps to the given values:
Given:
Mass of KCl + impurities = 0.2500 g
Mass of AgCl = 0.2912 g
Molar mass of AgCl = 143.32 g/mol
Molar mass of KCl = 74.55 g/mol
1. Calculate the mass of AgCl formed:
Mass of AgCl = 0.2912 g
2. Determine the moles of AgCl formed:
Moles of AgCl = 0.2912 g / 143.32 g/mol = 0.002030 mol
3. Since AgNO3 is in excess, all the Cl in AgCl comes from the KCl in the sample.
Moles of KCl = Moles of Cl in AgCl = 0.002030 mol
4. Determine the moles of KCl sample:
Moles of KCl sample = 0.002030 mol
5. Calculate the mass of KCl in the sample:
Mass of KCl in the sample = 0.002030 mol * 74.55 g/mol = 0.1512 g
6. Calculate the percentage of KCl in the sample:
Percentage of KCl = (0.1512 g / 0.2500 g) * 100 = 60.48%
Therefore, the percentage of KCl in the sample is approximately 60.48%.
To calculate the percentage of KCl in the sample, we need to determine the mass of KCl and the total mass of the sample.
Given:
Mass of impure sample = 0.2500 g
Mass of AgCl obtained = 0.2912 g
First, we need to find the mass of Cl in AgCl:
Since AgCl contains 1 Cl atom, the molar mass of Cl is equal to the molar mass of AgCl (143.32 g/mol).
Mass of Cl in AgCl = Mass of AgCl = 0.2912 g
Next, we can find the number of moles of Cl in AgCl:
Number of moles of Cl = Mass / molar mass
Number of moles of Cl = 0.2912 g / 143.32 g/mol
Now, we need to find the molar mass of KCl, which is the sum of the molar masses of K and Cl:
Molar mass of KCl = (molar mass of K) + (molar mass of Cl)
Molar mass of KCl = 39.10 g/mol + 35.45 g/mol
To find the mass of KCl, we calculate the number of moles of Cl and multiply it by the molar mass of KCl:
Mass of KCl = (Number of moles of Cl) x (Molar mass of KCl)
Finally, we can calculate the percentage of KCl in the sample:
Percentage of KCl = (Mass of KCl / Mass of sample) x 100
By plugging in the values into the formulas and performing the calculations, we can obtain the percentage of KCl in the sample.
KCl + AgNO3 ==> AgCl + KNO3
mols AgCl formed = g/molar mass = 0.2912/143.34 = 0.0020315
The ratio of KCl to AgCl is 1:1; therefore, mols KCl to start must be 0.0020315. Grams KCl = mols KCl x molar mass KCl = ?
% KCl = (grams KCl/mass sample)*100 = ?
Post your work if you get stuck. Check those molar mass and calculations. I tried to do that from memory.