Final answer:
To calculate the mass of hydrogen collected when zinc reacts with hydrochloric acid, adjust the pressure for water vapor, convert measurements to standard units, use the ideal gas law to find the number of moles, and apply the molar mass of hydrogen to determine the mass.
Step-by-step explanation:
The student is asking about calculating the mass of hydrogen gas collected when zinc reacts with hydrochloric acid. To find the mass of hydrogen collected, we can use the ideal gas law equation, PV = nRT, where P is the pressure of hydrogen gas, V is the volume, n is the number of moles, R is the universal gas constant, and T is the temperature in Kelvin.
First, we must adjust the pressure of the hydrogen gas to account for the vapor pressure of water. The pressure of the hydrogen gas alone is 753 mmHg minus the vapor pressure of water at 25°C, which is 23.78 mmHg, giving us 729.22 mmHg. Convert this to atmospheres (1 atm = 760 mmHg). Next, convert the temperature to Kelvin (K = °C + 273.15) and the volume to liters. Use the ideal gas law to solve for the number of moles of hydrogen gas (n).
Finally, calculate the mass of hydrogen using the molar mass of hydrogen (approximately 2.016 g/mol). For every mole of hydrogen gas, there are 2.016 grams of mass.