the percent by mass of copper in cubr2 is use %element = \\frac{total mass of element in compound}{molar…

Explanation:

Step1: Find molar mass of Cu

The molar mass of copper (Cu) is $M_{Cu}=63.55\ g/mol$.

Step2: Find molar mass of Br

The molar mass of bromine (Br) is $M_{Br}=79.90\ g/mol$.

Step3: Calculate molar mass of CuBr₂

The molar mass of $CuBr_{2}$ is $M = M_{Cu}+ 2\times M_{Br}=63.55 + 2\times79.90=63.55 + 159.8=223.35\ g/mol$.

Step4: Calculate mass - percent of Cu

Using the formula $%\text{Element}=\frac{\text{total mass of element in compound}}{\text{molar mass of compound}}\times100$, for Cu in $CuBr_{2}$, we have $%\text{Cu}=\frac{63.55}{223.35}\times 100\approx 28.45%$.

Answer:

28.45%