A 0.887g sample of a mixture of nacl and kcl is dissolved in water , and the solution is then treated with an excess of agn03 to yield 1.913g of agcl. Calculate the percent by mass of nacl in the mixture
1.913/143g/mol = 0.01337
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0.887/58.44g/mol = 0.01517
Percent by mass of NaCl = (0.01517/0.01337) x 100 = 113.3%
To calculate the percent by mass of NaCl in the mixture, we need to first find the masses of NaCl and KCl present in the sample.
Let's assume the mass of NaCl in the sample is x grams, and the mass of KCl is (0.887 - x) grams.
When the sample is treated with excess AgNO3, AgCl is formed. The molar mass of AgCl is 143 g/mol.
From the given information, 1.913 grams of AgCl is obtained. We can convert this mass into moles using the formula:
moles of AgCl = mass of AgCl / molar mass of AgCl
moles of AgCl = 1.913 g / 143 g/mol
moles of AgCl ≈ 0.01337 mol
Since AgCl is formed from AgNO3 and chloride ions from NaCl and KCl, we can write a balanced chemical equation:
AgNO3 + NaCl → AgCl + NaNO3
From the equation, we know that 1 mole of AgCl is formed from 1 mole of NaCl. Therefore, the number of moles of NaCl in the sample is also approximately 0.01337 mol.
Now we can calculate the percent by mass of NaCl in the mixture:
mass percent of NaCl = (mass of NaCl / total mass of mixture) * 100
mass percent of NaCl = (0.01337 mol x molar mass of NaCl / 0.887 g) * 100
The molar mass of NaCl is 58.44 g/mol.
mass percent of NaCl = (0.01337 mol x 58.44 g/mol / 0.887 g) * 100
mass percent of NaCl ≈ 8.80 %
Therefore, the percent by mass of NaCl in the mixture is approximately 8.80%.
To calculate the percent by mass of NaCl in the mixture, follow these steps:
1. Determine the molar mass of AgCl (silver chloride) using the atomic masses of silver (Ag) and chlorine (Cl).
Ag: 107.87 g/mol
Cl: 35.45 g/mol
Molar mass of AgCl = Ag (107.87 g/mol) + Cl (35.45 g/mol) = 143.32 g/mol
2. Convert the mass of AgCl obtained (1.913 g) to moles by dividing it by the molar mass obtained in step 1.
Moles of AgCl = 1.913 g / 143.32 g/mol ≈ 0.01337 mol
3. Since AgCl is formed from the reaction of NaCl and AgNO3, the moles of AgCl formed will be equal to the moles of Cl- ions from NaCl.
4. Determine the molar mass of Cl (chlorine) using the atomic mass.
Cl: 35.45 g/mol
5. Calculate the moles of Cl- ions by multiplying the moles of AgCl obtained in step 2 by the ratio between moles of Cl- ions and moles of AgCl.
Moles of Cl- ions = 0.01337 mol × (1 mol Cl- ion / 1 mol AgCl) = 0.01337 mol
6. Since NaCl consists of 1 Na+ ion and 1 Cl- ion, the moles of Na+ ions will be equal to the moles of Cl- ions.
7. Calculate the moles of Na+ ions by multiplying the moles of Cl- ions obtained in step 5 by the ratio between moles of Na+ ions and moles of Cl- ions.
Moles of Na+ ions = 0.01337 mol × (1 mol Na+ ion / 1 mol Cl- ion) = 0.01337 mol
8. Calculate the mass of NaCl by multiplying the moles of Na+ ions obtained in step 7 by the molar mass of NaCl.
Mass of NaCl = 0.01337 mol × (22.99 g/mol + 35.45 g/mol) ≈ 0.892 g
9. Finally, calculate the percent by mass of NaCl in the mixture by dividing the mass of NaCl obtained in step 8 by the initial mass of the mixture and multiplying it by 100.
Percent by mass of NaCl = (0.892 g / 0.887 g) × 100 ≈ 100.56%
Therefore, the percent by mass of NaCl in the mixture is approximately 100.56%.