what is the percent composition of CuBr2?
The correct answer and explanation is:
Correct Answer:
The percent composition of CuBr₂ is:
- Copper (Cu): 28.45%
- Bromine (Br): 71.55%
Explanation:
To calculate the percent composition of a compound, determine the molar mass of each element in the compound and then divide the mass of each element by the total molar mass of the compound. Finally, multiply by 100 to get the percentage.
The chemical formula CuBr₂ contains:
- 1 atom of copper (Cu)
- 2 atoms of bromine (Br)
Start by finding the atomic masses from the periodic table:
- Copper (Cu) = 63.55 g/mol
- Bromine (Br) = 79.90 g/mol
Calculate the total molar mass of CuBr₂:
- Total molar mass = (1 × 63.55) + (2 × 79.90)
- Total molar mass = 63.55 + 159.80
- Total molar mass = 223.35 g/mol
Now calculate the mass percentage of each element:
Copper (Cu):
- (63.55 / 223.35) × 100 = 28.45%
Bromine (Br):
- (159.80 / 223.35) × 100 = 71.55%
The percent composition gives insight into the ratio of elements in a compound by mass. This information is essential in chemistry for tasks like chemical analysis, preparing reagents, and understanding molecular structure. For example, in this compound, although there are two bromine atoms for every copper atom, the mass percentage shows bromine makes up the majority of the compound’s weight. This is due to bromine having a higher atomic mass than copper. Understanding percent composition is useful when converting between mass and moles in stoichiometric calculations or when assessing purity in a laboratory setting.