Question

"The following reaction is used to generate hydrogen gas in the laboratory. If 243 mL of gas is collected at 25°C and has a total pressure of 745 mm Hg, what mass of hydrogen is produced? A possibly useful table of water vapor pressures is provided below.

Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g) T (°C) P (mm Hg)
20 17.55
25 23.78
30 31.86"

Answer 1

To find the mass of hydrogen produced, calculate the partial pressure of hydrogen by subtracting the vapor pressure of water at the reaction temperature from the total pressure, then use the ideal gas law to find the moles of hydrogen, and finally multiply by the molar mass of hydrogen.

Step-by-step explanation:

The calculation of the mass of hydrogen produced in the reaction involves using the ideal gas law formula and taking into account the vapor pressure of water at the given temperature. First, we need to calculate the partial pressure of hydrogen by subtracting the water vapor pressure from the total pressure. Then, we can use the ideal gas law (PV=nRT) to find the number of moles of hydrogen, and finally, convert moles to mass using the molar mass of hydrogen.

Step 1: Calculate the partial pressure of hydrogen (PH2) by subtracting the vapor pressure of water at 25°C (given as 23.78 mm Hg) from the total pressure.
PH2 = Total pressure - Vapor pressure of water
PH2 = 745 mm Hg - 23.78 mm Hg

Step 2: Convert pressure from mm Hg to atm and volume from mL to L. Use the ideal gas law to calculate the number of moles (n) of hydrogen (Remember to convert temperature to Kelvin by adding 273.15 to the Celsius value).

Step 3: Calculate the mass of hydrogen by multiplying the number of moles by the molar mass of hydrogen (approximately 2.02 g/mol).

Answer 2

To calculate the mass of hydrogen produced in the reaction, we can use the ideal gas law equation. Using the given pressure, volume, and temperature, we can calculate the number of moles of hydrogen gas produced. Then, we can multiply the number of moles by the molar mass of hydrogen to find the mass.

Step-by-step explanation:

To calculate the mass of hydrogen produced in the reaction, we need to use the ideal gas law equation: PV = nRT. We have the pressure (745 mm Hg) and volume (243 mL) of the gas, as well as the temperature (25°C), so we can rearrange the equation to solve for the number of moles of hydrogen gas (n). Once we have the number of moles, we can calculate the mass using the molar mass of hydrogen. The molar mass of hydrogen is 2 g/mol, so we can multiply the number of moles by the molar mass to find the mass of hydrogen produced.

Let's first convert the pressure to atm:

P = 745 mmHg * (1 atm / 760 mmHg) = 0.9776 atm

Next, let's convert the volume to liters:

V = 243 mL * (1 L / 1000 mL) = 0.243 L

Now we can plug the values into the ideal gas law equation:

n = PV / RT = (0.9776 atm * 0.243 L) / (0.0821 atm·L/mol·K * (25°C + 273.15 K))

n = 0.00956 mol

Finally, we can calculate the mass of hydrogen:

Mass = n * molar mass = 0.00956 mol * 2 g/mol = 0.0191 g