Suppose an ore sample contains 11.01 % impurity in addition to a mixture of Cu2S and CuS. Heating 102.5 g of the mixture produces 74.90 g of solid which is 88.18 % copper. What is the mass percent CuS in the ore?
I would approach the problem this way.
102.5 g Cu2S + CuS + 11.01% impurity; therefore, mass of impurity is 102.5 x 0.1101 = 11.28 which means
mass Cu2S + mass CuS = 102.5-11.28 = 91.21g.
The problem isn't clear what happens to the impurity when heated; I suppose we are to assume it is inert.
Let x = mass Cu2S
and y = mass CuS
---------------------
x + y = 91.21
x(2*atomic mass Cu/molar mass Cu2S) + y(atomic mass Cu/molar mass CuS) = 74.90*0.8818
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Two equations in two unknowns. Solve for x and y
Then %CuS = (mass CuS/mass sample)*100 = ?
Post your work if you get stuck.
Note: x + y = 91.21 is just mass Cu2S + mass CuS = mass sample-mass impurity.
x(2*atomic mass Cu/molar mass Cu2S)= mass Cu contributed by Cu2S in the sample.
y(atomic mass Cu/molar mass CuS) = mass Cu contributed by CuS in the sample.
The sum of Cu contributed by Cu2S and Cu = mass Cu in the heated sample = 74.90*0.8818.
i tried to solve for x and y, but when i put them in that form, and then solved for only x, and then plugged it in to the equation, it just cancels everything out.
am i suppose to make one equation
x(Cu2/Cu2S)+y(Cu/CuS)= 91.21
and the other equation
x(Cu2/Cu2S)+y(Cu/CuS)= 74.90(.8818)
i havent tried these 2 equations yet
or how about i make the first equation
x + y =91.21
i have tried this, and apparently this is not the method, is there another way?
my answers are a little different because the numbers changed,
i got 12.7% for CuS and 75.83% for Cu2S. it almost added to my needed percent of 88.56%.
i even tried to recalculate, incause i left out some numbers, but it didn't work, maybe i will try again, any suggestions
To find the mass percent of CuS in the ore, we need to use the given information and apply some calculations.
Let's break down the information provided:
1. The ore sample contains 11.01% impurity, which means that the remaining portion is the mixture of Cu2S and CuS.
2. When the mixture is heated, it produces 74.90 g of solid, which is 88.18% copper. This means that the rest of the solid is the impurity.
Now, we can approach the problem step by step:
Step 1: Calculate the amount of impurity in the solid obtained.
To do this, multiply the mass of the solid by the percentage of impurity:
Mass of impurity = 74.90 g * (100% - 88.18%)
Step 2: Calculate the mass of copper in the solid obtained.
Since the solid is 88.18% copper, we can calculate the mass by multiplying the mass of the solid by the percentage of copper:
Mass of copper = 74.90 g * 88.18%
Step 3: Calculate the mass of CuS in the solid obtained.
Since the remaining portion of the solid is CuS, we subtract the mass of copper from the total mass of the solid:
Mass of CuS = Mass of solid obtained - Mass of copper
Step 4: Calculate the mass percent of CuS in the ore.
To find this, divide the mass of CuS by the total mass of the ore sample and multiply by 100:
Mass percent of CuS = (Mass of CuS / Mass of ore sample) * 100
Now, plug in the values and perform the calculations to get the final answer.