Impure sample of table salt that weighed 0.8421g, when dissolved in water and treated with excess AgNO3, formed 2.044g of AgCl. What is the percentage of NaCl in the impure sample?
Do I need the molecular weight to start this equation? Where do I start?
Same place you started for BaSO4 problem I worked for you.
%NaC= (mass NaCl/mass sample)*100
mass sample = 0.8241 g.
mass AgCl = 2.044 g
moles AgCl = g/molar mass = ??
moles Cl is the same as moles AgCl. moles NaCl is same as mols AgCl.
moles NaCl x molar mass NaCl = mass NaCl.
Substitute into the top equation and solve for %NaCl.
To calculate the percentage of NaCl in the impure sample, you don't need the molecular weight (but it may be useful later on).
Here's how you can solve the problem step by step:
Step 1: Determine the molar mass of AgCl
- The molar mass of Ag is 107.87 g/mol
- The molar mass of Cl is 35.45 g/mol
So, the molar mass of AgCl is 107.87 g/mol + 35.45 g/mol = 143.32 g/mol
Step 2: Calculate the number of moles of AgCl formed
- The mass of AgCl formed is 2.044 g
- Divide the mass by the molar mass to get the number of moles: 2.044 g / 143.32 g/mol = 0.0143 mol
Step 3: Determine the number of moles of NaCl in the impure sample
Since AgCl is formed from the reaction of AgNO3 with NaCl, we can use stoichiometry to determine the number of moles of NaCl.
Looking at the balanced equation:
AgNO3 + NaCl -> AgCl + NaNO3
The ratio between AgCl and NaCl is 1:1. This means that for every 1 mole of AgCl formed, 1 mole of NaCl is consumed.
Therefore, the number of moles of NaCl in the impure sample is also 0.0143 mol.
Step 4: Calculate the percentage of NaCl in the impure sample
- The mass of the impure sample is given as 0.8421 g
- Divide the number of moles of NaCl by the mass of the impure sample and multiply by 100 to get the percentage:
(0.0143 mol / 0.8421 g) * 100 = 1.7%
Therefore, the percentage of NaCl in the impure sample is approximately 1.7%.
To solve this question, you need to use the concept of stoichiometry and the law of conservation of mass. You do not need the molecular weight of NaCl to begin this equation, as you can directly calculate the percentage of NaCl in the impure sample using the given information.
The first step is to determine the amount of NaCl reacting with AgNO3 to form AgCl. To do this, you need to establish the stoichiometric ratio between NaCl and AgCl, which can be determined through the balanced chemical equation:
2NaCl + AgNO3 -> 2AgCl + NaNO3
From the balanced equation, you can see that the mole ratio between NaCl and AgCl is 2:2 or 1:1. This means that for every 1 mole of NaCl, 1 mole of AgCl is produced.
Next, you need to calculate the number of moles of AgCl formed. To do this, divide the mass of AgCl formed (2.044g) by the molar mass of AgCl. The molar mass of AgCl is the sum of the atomic masses of silver (Ag) and chlorine (Cl), which are 107.87 g/mol and 35.45 g/mol, respectively.
Moles of AgCl = Mass of AgCl / Molar mass of AgCl
Moles of AgCl = 2.044g / (107.87g/mol + 35.45g/mol)
Moles of AgCl = 0.01876 mol
Since the stoichiometric ratio between NaCl and AgCl is 1:1, the number of moles of NaCl reacting with AgNO3 is also 0.01876 mol.
The next step is to calculate the percentage of NaCl in the impure sample. To do this, divide the moles of NaCl by the total moles of the impure sample and multiply by 100.
Percentage of NaCl = (Moles of NaCl / Total moles of impure sample) x 100
Percentage of NaCl = (0.01876 mol / Total moles of impure sample) x 100
Now, we need to determine the total moles of the impure sample. To do this, divide the weight of the impure sample by the molar mass of NaCl.
Total moles of impure sample = Weight of impure sample / Molar mass of NaCl
Total moles of impure sample = 0.8421g / 58.44g/mol (molar mass of NaCl)
Now, substitute this value into the equation to find the percentage of NaCl:
Percentage of NaCl = (0.01876 mol / (0.8421g / 58.44g/mol)) x 100
Calculate and simplify to find the final answer.