Answer:
0.544g
Explanation:
To calculate the mass of oxygen collected, we can calculate the number of moles of oxygen collected and multiply this by the molar mass of the oxygen molecule.
To calculate the number of moles of oxygen collected, we can use the ideal gas equation I.e PV = nRT
Rearranging the equation, n =PV/RT
We now identify each of the terms below before substituting and calculating.
n = number of moles, which we are calculating.
R = molar gas constant = 62.64 L.Torr. K^-1. mol^-1
V = volume = 500ml : 1000ml ÷ 1L, hence , 500ml = 500/1000 = 0.5L
T = temperature = 25 degrees Celsius = 273 + 25 = 298K
P = pressure. But since the gas was collected over water, we subtract the vapour pressure of water from the total pressure = 644 - 23.8 =620.2 torr
We substitute these values into the equation to yield the following:
n = (620.2× 0.5) ÷ ( 62.64 × 298)
n = apprx 0.017 moles
To calculate the mass of oxygen collected, we need the molar mass of oxygen. The molecular formula of oxygen is O2, atomic mass of oxygen= 32g/mol
Thus the mass of oxygen collected = 0.017 mole × 32g/mol = 0.544g
