a sample of indium chloride is known to be contaminated with sodium chloride. The contaminated sample weighs 2.87 g. When the contaminated sample is treated with excess AgNO3(aq), 5.79 grams of AgCl(s) are obtained. What is the percentage by mass of InCl3 in the sample?
To find the percentage by mass of InCl3 in the sample, we need to determine the masses of sodium chloride (NaCl) and indium chloride (InCl3) separately.
Let's start by calculating the mass of AgCl obtained from the reaction between AgNO3 and the chloride salts (NaCl and InCl3) in the sample.
1. Determine the molar mass of AgCl:
- Ag: 107.87 g/mol (silver atomic mass)
- Cl: 35.45 g/mol (chlorine atomic mass)
Molar mass of AgCl = Ag (1 mol) + Cl (1 mol)
= 107.87 g/mol + 35.45 g/mol
= 143.32 g/mol
2. Use the molar mass of AgCl to convert the mass of AgCl obtained to moles:
Moles of AgCl = Mass of AgCl / Molar mass of AgCl
= 5.79 g / 143.32 g/mol
≈ 0.040 g
Now, let's use the moles of AgCl formed to determine the moles of Cl present in the sample.
3. Since 1 mol of AgCl contains 1 mol of Cl, the moles of Cl in AgCl are the same as the moles of AgCl:
Moles of Cl = Moles of AgCl
≈ 0.040 mol
4. Calculate the mass of Cl in the sample:
Mass of Cl = Moles of Cl × Molar mass of Cl
= 0.040 mol × 35.45 g/mol
≈ 1.42 g
By subtracting the mass of Cl from the total mass of the contaminated sample, we can find the mass of InCl3 in the sample.
5. Mass of InCl3 = Total mass of contaminated sample - Mass of Cl
= 2.87 g - 1.42 g
= 1.45 g
Finally, we can calculate the percentage by mass of InCl3 in the sample.
6. Percentage by mass of InCl3 = (Mass of InCl3 / Total mass of sample) × 100%
= (1.45 g / 2.87 g) × 100%
≈ 50.5%
Therefore, the percentage by mass of InCl3 in the sample is approximately 50.5%.