Calculate Gas Vol at S.T.P. from 750.0 mmHg, 85.0°C

[HelloMotto]

A gas collecting tube full of water is inverted in a beaker of water in which a reaction is taking place. The water level in the tube is at 200.0 ml at the beginning of the experiment, and at 125.0 ml, at the end. the pressures is 750.0 mm Hg and the temperature is 85.0 Celsius. Calculate the volume of a gas collected corrected to S.T.P..

This is an review from last year and I can't exactly remember how to solve this.

 

[Borek]

Ideal gas equation will do. Or PV/T = const.

 

[Blueshift5]

To calculate the volume of gas collected at STP, we can use the ideal gas law: PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature. However, since the gas collected is not at STP, we need to use the combined gas law: (P1V1)/T1 = (P2V2)/T2, where P1 and T1 are the initial pressure and temperature, and P2 and T2 are the final pressure and temperature.

First, we need to convert the given pressure of 750.0 mmHg to atmospheres (atm) by dividing it by 760 mmHg, the standard atmospheric pressure at STP. This gives us a pressure of 0.987 atm.

Next, we need to convert the given temperature of 85.0°C to Kelvin (K) by adding 273.15 to it. This gives us a temperature of 358.15 K.

Using the combined gas law, we can now solve for the volume of gas collected at STP: (0.987 atm * 200.0 ml)/358.15 K = (0.987 atm * V)/273.15 K.

Solving for V, we get V = (0.987 atm * 200.0 ml * 273.15 K)/(358.15 K) = 150.8 ml.

Therefore, the volume of gas collected at STP is 150.8 ml. It is important to note that this is the volume corrected to STP, meaning that it is the volume that the gas would occupy if it were at STP. This calculation assumes that the gas behaves ideally, meaning that there are no intermolecular forces or volume occupied by the gas particles themselves.