Final answer:
To find the pressure of the hydrogen gas formed in a reaction of magnesium with hydrochloric acid, subtract the vapor pressure of water at 24.0 °C from the total pressure of 795.0 mmHg.
Step-by-step explanation:
The question involves a chemical reaction between magnesium and hydrochloric acid where hydrogen gas is produced. To determine the pressure of hydrogen gas formed, one must subtract the vapor pressure of water from the total gas pressure collected. The total pressure given is 795.0 mmHg and the reaction occurs at 24.0 °C. The vapor pressure of water at this temperature can be found in a textbook or a resource table. It is important to remember that the total pressure of a gas collected over water is the sum of the partial pressure of the gas itself plus the vapor pressure of water at that specific temperature.
When a gas is collected over water, the total pressure is equal to the partial pressure of the gas plus the vapor pressure of water. In this reaction, the hydrogen gas is being collected over water. The total pressure of the gas collected is given as 795.0 mmHg. We need to find the pressure of the hydrogen gas formed. To do that, we need to subtract the vapor pressure of water from the total pressure. The vapor pressure of water at 24.0 °C is 22.4 mmHg. So, the pressure of the hydrogen gas formed is 795.0 mmHg - 22.4 mmHg = 772.6 mmHg.