G-Chem Quation

[dentalwanabee]

stuck at this question, please help.

Q: If all of the Chloride in a 5.0g sample of an unknown metal chloride is percipitated as AgCl with 70.9 milliliteres of 0.201M AgNO3, what is the % of chloride in the sample?

a. 50.55%
b. 20.22%
c. 1.43%
d. 10.10%
e. none of the above

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[armorshell]

stuck at this question, please help.

Q: If all of the Chloride in a 5.0g sample of an unknown metal chloride is percipitated as AgCl with 70.9 milliliteres of 0.201M AgNO3, what is the % of chloride in the sample?

a. 50.55%
b. 20.22%
c. 1.43%
d. 10.10%
e. none of the above

Solve it using a dimensional analysis; you're given the mass of the sample (g), the concentration and volume of the precipitant (mol/L and L) and you know the molecular weight of chlorine (g/mol).

From this you can get:
L * mol/L * g/mol = the grams of Cl in the sample. Then you divide by the total mass of the sample * 100% to get the answer, which should be d.

 

[714guy]

stuck at this question, please help.

Q: If all of the Chloride in a 5.0g sample of an unknown metal chloride is percipitated as AgCl with 70.9 milliliteres of 0.201M AgNO3, what is the % of chloride in the sample?

a. 50.55%
b. 20.22%
c. 1.43%
d. 10.10%
e. none of the above

I got D (10.10%). I haven't done this in a while but I'll try to explain the best i can.

First I wrote out the balanced RXN: unknown+Cl(s) + AgNO3 --> AgCl + NO3.

Next is the stiochiometery equation: (.201 mol/L)(1 L/ 1000Ml)(70.9Ml)(1 mol AgNO3/1 mol AgCl) (1 mol Cl/1 mol AgCl) (35.45 g of Cl/ 1mol of Cl) = 0.505 g of Cl

% of Cl in sample: 0.505g/5.00g * 100 = 10.10%

Explanation: So you start with 79mL of .201M of AgNO3, then you'll need to find how much AgCl(s) you can produce from the reaction. It says that all the Cl was used up so you know that all of it will be in the AgCl. After finding the moles of AgCl you made, you know that 1 mole AgCl contains 1 mole of Cl, then you'll find the weight of Cl. then the rest is just part/whole etc.

 

[supraman]

just stinks having no calc to use