a mixture contains only sodium chloride and potassium chloride. a .1586-g sample of the mixture was dissolved in water. it took 22.90 mL of 0.1000 M AgNO3 to completely precipitate all the chloride present. what is the composition(by Mass percent) of the mixture?
Two equations and two unknowns. Solve simultaneously.
eqn 1.
g NaCl + g KCl = 0.1586g
eqn 2.
mol AgCl from NaCl + mol AgCl from KCl = mol AgCl total
Now put those into math form.
Let X = g NaCl
and Y = g KCl
MM stands for molar mass.
---------------------
eqn 1.
X + Y = 0.1586 g
eqn 2.
(X/MM NaCl) + (Y/MM KCl) = 0.02290*0.1000
Find X and Y, then
%NaCl = (X/0.1586)*100 = ?
Post your work if you get stuck.
^KCl = (Y/0.1586)*100 = ?
To find the composition of the mixture, we need to determine the mass of sodium chloride (NaCl) and potassium chloride (KCl) present in the sample.
Let's start by calculating the number of moles of silver nitrate (AgNO3) used to precipitate the chloride ions present in the sample.
Given:
Mass of the mixture = 0.1586 g
Volume of AgNO3 solution used = 22.90 mL = 0.02290 L
Concentration of AgNO3 solution = 0.1000 M
Step 1: Calculate the number of moles of AgNO3 used.
Moles of AgNO3 = concentration * volume
Moles of AgNO3 = 0.1000 mol/L * 0.02290 L
Step 2: Calculate the number of moles of chloride ions (Cl-) present in the sample.
Since AgNO3 reacts with Cl- to form a white precipitate AgCl, the moles of AgNO3 used will be equal to the moles of Cl- present in the sample.
Moles of Cl- = Moles of AgNO3
Step 3: Calculate the mass of Cl- present in the sample.
Molar mass of Cl- (from the periodic table) = 35.45 g/mol
Mass of Cl- = Moles of Cl- * Molar mass of Cl-
Now, let's calculate the mass percent composition of NaCl and KCl in the mixture.
Given:
Total mass of the mixture = 0.1586 g
Step 4: Assume the mass of NaCl as x g. Then, the mass of KCl will be (0.1586 - x) g.
Step 5: Calculate the number of moles of NaCl and KCl using their respective masses.
Moles of NaCl = Mass of NaCl / Molar mass of NaCl
Moles of KCl = Mass of KCl / Molar mass of KCl
Step 6: Calculate the mass percent composition.
Mass percent of NaCl = (Mass of NaCl / Total mass of the mixture) * 100
Mass percent of KCl = (Mass of KCl / Total mass of the mixture) * 100
By following these steps and substituting the values, you can find the composition (mass percent) of the mixture.
To find the composition by mass percent of the mixture, we need to determine the mass of sodium chloride and potassium chloride in the sample.
First, let's calculate the moles of AgNO3 that reacted with the chloride ions in the mixture using the volume and concentration of AgNO3.
The equation for the reaction between AgNO3 and chloride ions is:
AgNO3 + Cl- → AgCl + NO3-
From the balanced equation, we know that one mole of AgNO3 reacts with one mole of Cl-. Therefore, the moles of AgNO3 that reacted with the chloride ions is equal to the moles of chloride ions in the mixture.
moles of AgNO3 = volume of AgNO3 (L) × concentration of AgNO3 (mol/L)
moles of AgNO3 = 0.02290 L × 0.1000 mol/L
Next, we need to convert the moles of AgNO3 that reacted to moles of chloride ions.
Since each chloride ion in sodium chloride (NaCl) and potassium chloride (KCl) reacts with one AgNO3 molecule, the moles of chloride ions is equal to the moles of AgNO3.
moles of chloride ions = moles of AgNO3
To find the mass of NaCl and KCl, we need to use the molar masses of sodium chloride (58.44 g/mol) and potassium chloride (74.55 g/mol).
mass of NaCl = moles of NaCl × molar mass of NaCl
mass of KCl = moles of KCl × molar mass of KCl
Finally, we can calculate the mass percentage of each component in the mixture.
mass percent of NaCl = (mass of NaCl / mass of mixture) × 100
mass percent of KCl = (mass of KCl / mass of mixture) × 100
To summarize:
1. Calculate the moles of AgNO3: moles of AgNO3 = 0.02290 L × 0.1000 mol/L
2. Determine the moles of chloride ions: moles of chloride ions = moles of AgNO3
3. Calculate the mass of NaCl: mass of NaCl = moles of NaCl × molar mass of NaCl
4. Calculate the mass of KCl: mass of KCl = moles of KCl × molar mass of KCl
5. Calculate the mass of the mixture: mass of mixture = mass of NaCl + mass of KCl
6. Calculate the mass percent of NaCl: mass percent of NaCl = (mass of NaCl / mass of mixture) × 100
7. Calculate the mass percent of KCl: mass percent of KCl = (mass of KCl / mass of mixture) × 100
By following these steps, you can determine the composition of the mixture by mass percent. Remember to use the appropriate molar masses for NaCl and KCl in your calculations.