An experimental alloy contained by copper and tantalum. 3.7950 g of the alloy was dissolved and analyzed gravimetrically. The copper was precipitated and weighed as CuO, a mass of 0.1805 g was obtained. Calculate the %w/w Cu in the alloy. [Answer in 2 decimal places]
Convert 0.1805 g CuO to mass Cu and substitute into the percent formula of
%Cu = (mass Cu/mass sample)*100 = ?
is mass sample 0.1805?
No. Mass sample is 3.7950g.
mass CuO is 0.1805 from the problem.
To calculate the %w/w (percentage by weight) of copper in the alloy, we first need to determine the amount of copper in the sample.
1. Begin by calculating the amount of copper in the alloy:
- Mass of CuO obtained = 0.1805 g
- Since 1 mole of CuO contains 1 mole of Cu, we can use the molar mass of CuO to find the number of moles of Cu:
Molar mass of CuO = (atomic mass of Cu) + (atomic mass of O) = 63.55 g/mol + 15.999 g/mol = 79.55 g/mol
Moles of Cu = Mass of CuO / Molar mass of CuO = 0.1805 g / 79.55 g/mol
2. Next, determine the amount of Cu in the alloy:
- We know that 0.1805 g of CuO is equivalent to the amount of Cu in the alloy.
- Therefore, the mass of Cu in the alloy is also 0.1805 g.
3. Calculate the %w/w Cu in the alloy:
- %w/w Cu = (mass of Cu / mass of alloy) * 100
- Mass of alloy = 3.7950 g (given)
- %w/w Cu = (0.1805 g / 3.7950 g) * 100
Now, let's calculate the %w/w Cu:
%w/w Cu = (0.1805 g / 3.7950 g) * 100
%w/w Cu ≈ 4.76%
Therefore, the %w/w Cu in the alloy is approximately 4.76%.