2. Zinc metal reacts with HCL similarly to magnesium: Zn(s) + 2HCL(aq) = ZnCl2(aq) + H2(g). the H2 gas produced was collected over water at 25 degrees Celsius and had a volume of 7.80L at 0.980 atm. How many grams of Zn were consumed in the reaction? (Vapor pressure of water at 25C = 23.8mmHg)

Use PV = nRT

P = 0.980 - (23.8/760)
V = 7.8L
n = solve for this
R = 0.08206
T = 298
1 mol H2 = 1 mol Zn
g Zn = mols x molar mass.

19.8g

To solve this problem, we need to use the ideal gas law and the concept of partial pressures.

First, let's convert the given pressure of the H2 gas from atm to mmHg to maintain consistency in the units:

P(H2) = 0.980 atm * 760 mmHg/atm = 745.28 mmHg

Next, let's consider the effect of the water vapor pressure on the total pressure. The total pressure is the sum of the partial pressures of H2 gas and water vapor:

P(total) = P(H2) + P(vapor pressure of water)

P(vapor pressure of water) = 23.8 mmHg (given in the problem)

By rearranging the equation, we can calculate the partial pressure of the H2 gas:

P(H2) = P(total) - P(vapor pressure of water)
= 745.28 mmHg - 23.8 mmHg
= 721.48 mmHg

Now, let's use the ideal gas law to find the number of moles of H2 gas produced:

PV = nRT

n(H2) = (P(H2) * V) / (R * T)

where:
P(H2) is the partial pressure of H2 gas (in atm or mmHg)
V is the volume of the gas (in liters)
R is the ideal gas constant (0.0821 L·atm/(mol·K))
T is the temperature (in Kelvin)

Note: The temperature needs to be converted from Celsius to Kelvin by adding 273.15.

n(H2) = (721.48 mmHg * 7.80L) / (0.0821 L·atm/(mol·K) * (25 + 273.15) K)

By calculating the above expression, we can find the number of moles of H2 gas produced.

Now let's use the balanced chemical equation to find the number of moles of Zn consumed. According to the equation, one mole of Zn reacts with one mole of H2 gas:

n(Zn) = n(H2)

Finally, we can calculate the mass of Zn consumed using its molar mass:

mass(Zn) = n(Zn) * molar mass(Zn)

The molar mass of Zn can be found by looking up its atomic mass from the periodic table.