Chemistry, 23.11.2019 05:31, tj88345

Asample of oxygen gas is collected over water at 25°c and a total pressure of 644 torr. the volume of the gas collected is 500.0 ml. what mass of oxygen is collected? the vapor pressure of water at 25°c is 23.8 torr.

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answered: AtlFan6392

The mass of oxygen gas sample collected over water is 0.544 g.

The given parameters;

temperature of the oxygen gas, t = 25 °C total pressure of the gas, P = 644 torrvolume of the gas, V = 500 mLvapor pressure = 23.8 torrmolar mass of oxygen gas = 32 g/mol

The number of moles of the gas collected is calculated by using ideal gas equation as follows;

PV = nRT

where;

R is the ideal gas constant = 62.36 L.torr/mol.KP is the pressure of the gas = 644 torr - 23.8 torr = 620.2 torrT is the temperature of the gas = 25 + 273 = 298 KV is the volume of the gas = 500 mL = 0.5 L

The number of moles of the gas is calculated as follows;

$n = \frac{PV}{RT} \\\\n = \frac{620.2 \times 0.5}{62.36 \times 298} \\\\n = 0.017 \ mol$

The mass of oxygen gas collected is calculated as follows;

m = 0.017 (32 g/mol)

m = 0.544 g

Thus, the mass of oxygen gas sample collected over water is 0.544 g.

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answered: kalieghcook

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

answered: Guest

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answered: Guest

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Asample of oxygen gas is collected over water at 25°c and a total pressure of 644 torr. the volume o...