A 3.5g sample of potassium chloride(KCl)is dissolved in 10mL of water.The resulting solution is the added to 60mL of a 0.5M CaCl2 soltion. Assuming that the volume are additive,calculate the molar concentration and %w/v of each ion present in final soltion.
mols KCl = grams/molar mass = approx 0.5 but that's just a close guess.
mols CaCl2 added = M x L = approx 0.03 or 0.03 mols Ca^2+ and 0.06 mols Cl^-.
Total K = 0.5 and total volume = 0.07L, then M K^+ = mols/L = ?
total Cl = 0.5 + 0.06 = 0.56 and total volume is 60+10 = 70 mL = 0.07L then M Cl = mols/L.
Note that you must go through each calculations to get a good number and not an approximation.
Thank you very much for your replies, DrBob :)
To calculate the molar concentration and %w/v of each ion present in the final solution, we need to first determine the number of moles of each compound, and then use the volume and mass information to calculate the concentrations.
Let's start by calculating the number of moles of potassium chloride (KCl) in the 3.5g sample:
Step 1: Calculate the molar mass of KCl.
The molar mass of KCl is the sum of the atomic masses of potassium (K) and chlorine (Cl).
Molar mass of K = 39.10 g/mol
Molar mass of Cl = 35.45 g/mol
Molar mass of KCl = Molar mass of K + Molar mass of Cl = 39.10 + 35.45 = 74.55 g/mol
Step 2: Calculate the number of moles of KCl.
The number of moles (n) is calculated using the formula:
n = Mass / Molar mass
n = 3.5 g / 74.55 g/mol
Now, let's calculate the moles of CaCl2 in the 60 mL of a 0.5 M CaCl2 solution:
Step 1: Convert the volume from mL to L.
Volume of CaCl2 solution = 60 mL = 60/1000 = 0.06 L
Step 2: Calculate the number of moles of CaCl2.
The number of moles (n) is calculated using the formula:
n = c * V
where c is the concentration in M (mol/L), and V is the volume in L.
n = 0.5 M * 0.06 L
Now that we have calculated the number of moles of KCl and CaCl2, we can proceed to calculate the molar concentration and %w/v of each ion in the final solution.
Step 1: Calculate the total volume of the final solution.
The final volume is the sum of the volumes of water and CaCl2 solution added.
Total volume = 10 mL of water + 60 mL of CaCl2 solution = 70 mL
Step 2: Calculate the molar concentration of each ion.
Molar concentration (M) is calculated using the formula:
C = n / V
where n is the number of moles and V is the volume in L.
For potassium ions (K+):
Concentration of K+ (M) = Moles of K+ / Total volume (in L)
For calcium ions (Ca2+):
Concentration of Ca2+ (M) = Moles of Ca2+ / Total volume (in L)
Step 3: Calculate the %w/v of each ion.
%w/v is calculated as the mass of the solute (in grams) divided by the volume of the solution (in mL), multiplied by 100.
For potassium ions (K+):
%w/v of K+ = (Mass of K+ / Total volume) * 100
For calcium ions (Ca2+):
%w/v of Ca2+ = (Mass of Ca2+ / Total volume) * 100
By following these steps, you can calculate the molar concentration and %w/v of each ion present in the final solution.