Zinc metal is added to hydrochloric acid to generate hydrogen gas and is collected over a liquid whose vapor pressure is the same as pure water at 20.0°C (18 torr). The volume of the mixture is 1.7 L, and its total pressure is 0.810 atm.
Determine the number of moles of hydrogen gas present in the sample.
To solve this problem, we need to use the ideal gas law equation, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
We are given the total pressure (0.810 atm), the volume (1.7 L), and the temperature. However, we need to find the number of moles.
First, we need to convert the temperature from Celsius to Kelvin. The equation to convert from Celsius to Kelvin is K = °C + 273.15. So, 20.0°C + 273.15 = 293.15 K.
Now, let's rearrange the ideal gas law equation to solve for n:
n = PV / RT
n = (0.810 atm) * (1.7 L) / [(0.0821 L·atm/(mol·K)) * (293.15 K)]
n = (1.377 atm*L) / (24.083 L·atm/(mol·K))
n ≈ 0.057 mol
Therefore, there are approximately 0.057 moles of hydrogen gas present in the sample.