Answer:
%Cu = 66.4%
%S = 33.6%
Step-by-step explanation:
Step 1: Given data
Step 2: Calculate the mass of S
The mass of CuS is equal to the sum of the masses of Cu and S.
mCuS = mCu + mS
mS = mCuS - mCu
mS = 9.56 g - 6.35 g = 3.21 g
Step 3: Calculate the percent by mass of each element
We will use the following expression.
%Element = mElement / mCompound × 100%
%Cu = mCu / mCuS × 100% = 6.35 g / 9.56 g × 100% = 66.4%
%S = mS / mCuS × 100% = 3.21 g / 9.56 g × 100% = 33.6%