A 0.8552g sample of copper alloy is treated with 8 molar nitric acid and filtered and the precipitate is ignited giving a residue of 0.0632g of SnO2. The zinc is determined in one half of the filterate by precipitating it as ZnNH4PO4 and then igniting with 0.2231g of Zn2P2O7 is formed. In the other half of the filterate copper is determined as CuSCN giving a precipitate of 0.5874g. Calculate the percentage tin, zinc and copper in the sample.
% metal in sample = (mass metal/mass sample)*100 = ?
mm stands for molar mass.am is atomic mass.
mass Sn = mass SnO2 ppt x (am Sn/mm SnO2) = ?
mass Zn2P2O7 in 1/2 sample is 0.2231 and x 2 = mass Zn2P2O7 in all of the sample.
mass Zn = mass Zn2P2O7 x (2*am Zn/mm Zn2P2O7)*100 = ?
mass CuSCN in 1/2 sample is 0.5874 and x 2 = mass CuSCN in whole sample.
Mass Cu = mass CuSCN x (am Cu/mm CuSCN)*100 = ?
Post your work if you get stuck.
% SN = [mass SnO2/mm] * mm Sn
-------------------------------------* 100 =
Sample
5.82% Zn
You must have made a typo. 5.82% Sn is correct.
I'm lost when I find% Zinc and copper, how is the stoichiometry of the reaction?
To calculate the percentage of tin, zinc, and copper in the given sample, we need to determine the weights of each element present and then calculate their respective percentages.
Let's break down the problem step by step:
1. Calculation of Tin (Sn):
- The precipitate obtained after treating the copper alloy with nitric acid and filtering is SnO2.
- The weight of the SnO2 residue obtained is 0.0632g.
- Hence, the weight of tin (Sn) present in the sample is 0.0632g.
2. Calculation of Zinc (Zn):
- The zinc in one half of the filtrate is precipitated as ZnNH4PO4.
- We are given that 0.2231g of Zn2P2O7 is formed after ignition.
- From the balanced chemical equation, we know that 1 mole of Zn2P2O7 is formed from 2 moles of zinc (Zn).
- The molar mass of Zn2P2O7 is 339.88 g/mol.
- We can calculate the moles of Zn2P2O7 using its weight:
moles of Zn2P2O7 = weight of Zn2P2O7 / molar mass of Zn2P2O7 = 0.2231g / 339.88g/mol.
- Therefore, the moles of zinc (Zn) present in the sample are equal to half of the moles of Zn2P2O7 obtained.
- The molar mass of zinc (Zn) is 65.38 g/mol.
- We can calculate the weight of zinc (Zn) using its moles:
weight of Zn = moles of Zn * molar mass of Zn = (0.2231g / 339.88g/mol) * 65.38g/mol.
3. Calculation of Copper (Cu):
- The copper in the other half of the filtrate is determined as CuSCN.
- The weight of the precipitate obtained is 0.5874g.
- Hence, the weight of copper (Cu) present in the sample is 0.5874g.
4. Calculation of Percentages:
- To calculate the percentages, we need to divide the weight of each element by the initial weight of the sample (0.8552g) and multiply by 100.
- Percentage of tin (Sn) = (weight of tin (Sn) / initial weight of sample) * 100.
- Percentage of zinc (Zn) = (weight of zinc (Zn) / initial weight of sample) * 100.
- Percentage of copper (Cu) = (weight of copper (Cu) / initial weight of sample) * 100.
Now you can substitute the calculated values for each element and perform the calculations to find the percentages of tin, zinc, and copper in the given sample.