Question

How many grams of zinc oxide should be added to 200 g of 10% zinc oxide ointment to prepare an ointment containing 20% zinc oxide? (Powder Zno should be interpreted as 100% strength) le 10% of 200= 20 2n 8

Answer 1

The percent composition of zinc in the compound is 80.35%, and oxygen is 19.65%, with their sum confirming the calculation's accuracy at 100%.

Step-by-step explanation:

To calculate the percent composition of the zinc oxide compound, we use the mass of zinc and the total mass of the compound. Given that after decomposition we have 16.07 g of zinc from a 20.00 g sample of zinc oxide, the remaining mass would be oxygen.

Percent composition of zinc is calculated as follows:

1. Calculate the mass of oxygen by subtracting the mass of zinc from the total mass: 20.00 g – 16.07 g = 3.93 g of oxygen.
2. Calculate the percentage of zinc by dividing the mass of zinc by the total mass and multiplying by 100: (16.07 g / 20.00 g) × 100 = 80.35%.
3. Calculate the percentage of oxygen by dividing its mass by the total mass and multiplying by 100: (3.93 g / 20.00 g) × 100 = 19.65%.

The percent composition by mass for the compound is thus 80.35% zinc and 19.65% oxygen. It's important to note that the sum of these percentages equals 100%, confirming the calculation is correct.