A sample of the compound prepared in this experiment, weighing .1021g, is dissolved in HNO3 and diluted to a volume of 100mL. A 10mL aliquot of that solution is mixed with 10mL 6 M NH3. The [Cu(NH3)4 2+] in the resulting solution is 5.16x10^-3 M.
How many moles of Cu were in the original sample, which had been effectively diluted to a volume of 200mL?
How many grams of Cu were in the sample?
How many grams of Cl were in the sample?How many moles?
What is the formula of the Copper Chloride compound?
Personally I think the problem is stated in a screwy fashion. I don't get the "effective" dilution. Where did the Cl come from?
To calculate the moles of Cu in the original sample, we first need to find the moles of Cu(NH3)4^2+ in the resulting solution.
1. Calculate the moles of Cu(NH3)4^2+ in the resulting solution:
Molarity (M) = moles/volume (L)
moles = Molarity x volume
moles of Cu(NH3)4^2+ = (5.16x10^-3 M) x (10 mL / 1000 mL/L)
moles of Cu(NH3)4^2+ = 5.16x10^-5 moles
2. Given that a 10 mL aliquot is taken from a final volume of 200 mL, we can calculate the moles of Cu in the original sample:
moles of Cu = (moles of Cu(NH3)4^2+ x final volume) / aliquot volume
moles of Cu = (5.16x10^-5 moles x 200 mL) / 10 mL
moles of Cu = 1.03x10^-3 moles
Therefore, there are 1.03x10^-3 moles of Cu in the original sample.
To calculate the grams of Cu in the sample:
1. Use the moles of Cu calculated above:
moles = mass / molar mass
mass of Cu = moles x molar mass
The molar mass of Cu is 63.546 g/mol.
mass of Cu = 1.03x10^-3 moles x 63.546 g/mol
mass of Cu = 0.0656 grams
Therefore, there are 0.0656 grams of Cu in the sample.
To calculate the grams of Cl in the sample:
1. Calculate the moles of Cl in the sample by using the moles of Cu:
Since the compound is copper chloride (CuCl2), we know that there are two chloride ions for every one mole of copper.
moles of Cl = 2 x moles of Cu
moles of Cl = 2 x 1.03x10^-3 moles
moles of Cl = 2.06x10^-3 moles
2. Calculate the grams of Cl using the moles of Cl:
mass of Cl = moles of Cl x molar mass of Cl
The molar mass of Cl is 35.453 g/mol.
mass of Cl = 2.06x10^-3 moles x 35.453 g/mol
mass of Cl = 0.0731 grams
Therefore, there are 0.0731 grams of Cl in the sample.
The formula of the Copper Chloride compound is CuCl2.