To determine the percent composition of Zn in the compound, we need to first find the mass of Zn in the sample. We can use the given information to calculate the total mass of the compound, and then use the mass of Zn to determine its percent composition.
The total mass of the compound is 40.0 g, which is the sum of the masses of each element:
40.0 g = 32.14 g Zn + 7.86 g O
The mass of Zn in the sample is 32.14 g, which represents its percent composition in the compound. To express this as a percentage, we can divide the mass of Zn by the total mass of the compound and multiply by 100%:
percent composition of Zn = (32.14 g / 40.0 g) x 100% = 0.8035 x 100% = 80.35%
Thus, the percent composition of Zn in the compound is approximately 80.35%.