Final question..
An alloy used in aircraft construction consists of aluminium, copper and magnesium. An 11.34g sample of alloy was treated with alkali to dissolve the aluminium, leaving a residue of mass 2.73g. This residue was treated with dilute hydrochloric acid solution to dissolve the magnesium. The remaining residue had a mass of 0.90g.
Calculate the percentage composition of alloy.
%X = [(mass X)/mass sample] x 100
mass sample = 11.34g
mass of each of the follwoing is X.
mass Al = 11.34 - 2.73 g = ??
mass Cu = 0.90 g
mass Mg = 2.73 - 0.90 = ??
Post your work if you get stuck.
Thank you!!
To calculate the percentage composition of the alloy, we need to determine the mass of each component (aluminium, copper, and magnesium) in the alloy.
Let's start with aluminium (Al).
Given:
Sample mass = 11.34g
Residue mass after dissolving aluminium = 2.73g
To find the mass of aluminium, we subtract the mass of the residue from the sample mass:
Mass of Al = Sample mass - Residue mass after dissolving aluminium
Mass of Al = 11.34g - 2.73g
Mass of Al = 8.61g
Next, let's calculate the mass of magnesium (Mg).
Given:
Residue mass after dissolving magnesium = 0.90g
To find the mass of magnesium, we subtract the mass of the residue from the residue mass after dissolving aluminium:
Mass of Mg = Residue mass after dissolving aluminium - Residue mass after dissolving magnesium
Mass of Mg = 2.73g - 0.90g
Mass of Mg = 1.83g
Finally, we know the mass of copper (Cu) directly:
Mass of Cu = 0.90g
Now, we can calculate the percentage composition of each element in the alloy using the formula:
% Composition = (Mass of the component / Mass of the sample) × 100
For aluminium (Al):
% Al = (Mass of Al / Mass of the sample) × 100
% Al = (8.61g / 11.34g) × 100
% Al = 75.9%
For copper (Cu):
% Cu = (Mass of Cu / Mass of the sample) × 100
% Cu = (0.90g / 11.34g) × 100
% Cu = 7.9%
For magnesium (Mg):
% Mg = (Mass of Mg / Mass of the sample) × 100
% Mg = (1.83g / 11.34g) × 100
% Mg = 16.1%
Therefore, the percentage composition of the alloy is approximately:
Aluminium: 75.9%
Copper: 7.9%
Magnesium: 16.1%