Small quantities of hydrogen gas can be prepared in the laboratory by the addition of aqueous hydrochloric acid to metallic zinc.

Zn(s)+2HCl(aq) -> ZnCl2(aq)+ H2(g)

Typically, the hydrogen gas is bubbled through water for collection and becomes saturated with water vapor. Suppose 240 mL of hydrogen gas is collected at 30*C and has a total pressure of 1.032 atm by this process. What is the partial pressure of hydrogen gas in the sample? How many grams of zinc must have reacted to produce this quantity of hydrogen? (The vapor pressure of water is 32 torr at 30*C)

Total pressure = partial pressure H2O vapor + partial pressure H2 gas. You know two of the three, calculate the third one.

Use PV = nRT to calculate n = moles of H2 gas, then use stoichiometry to determine grams of Zn. Here is an example of a stoichiometry problem I've posted. Just follow the steps after you find moles from the PV = nRT equation.
http://www.jiskha.com/science/chemistry/stoichiometry.html

hydrogen = 0.990 atm, 9.55 x 10-3 mol H2, 0.625 g Zn

20 atm

Oh, chemistry! It's like magic, but with more explosions. Let's break it down, shall we?

First, we need to find the partial pressure of hydrogen gas in the sample. The total pressure is given as 1.032 atm, but we have to take into account the vapor pressure of water as well. So, we subtract the vapor pressure of water from the total pressure to get the partial pressure of hydrogen gas.

1.032 atm - 0.042 atm (since 32 torr = 0.042 atm) = 0.990 atm

So, the partial pressure of hydrogen gas in the sample is approximately 0.990 atm. Phew, that's a load off!

Now, let's move on to finding the number of grams of zinc that reacted to produce this quantity of hydrogen. For this, we need to use stoichiometry.

From the balanced chemical equation, we can see that the molar ratio between zinc and hydrogen gas is 1:1. That means for every mole of hydrogen gas produced, we need one mole of zinc. To find the number of moles of hydrogen gas, we can use the ideal gas law equation:

PV = nRT

Where:
P = partial pressure of hydrogen gas (0.990 atm)
V = volume of hydrogen gas (240 mL, but we have to convert it to liters by dividing by 1000: 240 mL / 1000 = 0.240 L)
n = number of moles of hydrogen gas (what we're trying to find)
R = ideal gas constant (0.0821 L·atm/(K·mol))
T = temperature in Kelvin (30°C + 273.15 = 303.15 K)

Plugging in the values:

(0.990 atm)(0.240 L) = n(0.0821 L·atm/(K·mol))(303.15 K)

Simplifying:

0.2376 atm·L = 24.9998 K·mol·n

Dividing both sides by 24.9998 K·mol:

0.00951 n = 0.2376

Solving for n:

n ≈ 25 moles

Since the molar ratio between zinc and hydrogen gas is 1:1 as I mentioned earlier, it means that 25 moles of zinc must have reacted to produce this quantity of hydrogen gas. But wait, we're not done yet!

To find the mass of zinc, we need to use the molar mass of zinc. The molar mass of zinc (Zn) is approximately 65.38 g/mol. So, we multiply the number of moles (25 moles) by the molar mass to get the mass of zinc:

25 moles × 65.38 g/mol ≈ 1634.5 grams of zinc

So, approximately 1634.5 grams of zinc must have reacted to produce this quantity of hydrogen gas.

Hope that answers your question and tickles your funny bone! Remember, chemistry is all about balancing equations and reactions, just like life. Keep smiling! 🤡

To determine the partial pressure of hydrogen gas in the sample, we need to consider the total pressure and the vapor pressure of water. The partial pressure of a gas is the pressure it would exert if it occupied the container alone.

First, let's convert the given total pressure to the same units as the vapor pressure of water.

1 atm = 760 torr

1.032 atm * (760 torr/1 atm) = 784.32 torr

Now, let's subtract the vapor pressure of water from the total pressure to find the partial pressure of hydrogen gas:

Partial pressure of hydrogen gas = Total pressure - Vapor pressure of water
= 784.32 torr - 32 torr (given vapor pressure of water at 30°C)
= 752.32 torr

Therefore, the partial pressure of hydrogen gas in the sample is 752.32 torr.

Next, let's calculate the amount of zinc that reacted to produce this quantity of hydrogen gas. We can use the ideal gas law equation to solve for the number of moles of hydrogen gas:

PV = nRT

Where:
P = partial pressure of hydrogen gas (752.32 torr)
V = volume of hydrogen gas (240 mL or 0.240 L)
n = number of moles of hydrogen gas
R = ideal gas constant (0.0821 L∙atm/mol∙K)
T = temperature in Kelvin (30°C + 273.15 = 303.15 K)

Rearranging the equation to solve for n:

n = PV / RT

Substituting the values:

n = (752.32 torr * 0.240 L) / (0.0821 L∙atm/mol∙K * 303.15 K)
n ≈ 0.0244 moles of hydrogen gas

From the balanced chemical equation, we can see that 1 mole of zinc reacts with 1 mole of hydrogen gas. Therefore, the number of moles of zinc that reacted is also 0.0244 moles.

Finally, we can calculate the mass of zinc that reacted using its molar mass. The molar mass of zinc (Zn) is approximately 65.38 g/mol.

Mass of zinc = number of moles of zinc * molar mass of zinc
= 0.0244 moles * 65.38 g/mol
≈ 1.60 grams of zinc

Therefore, approximately 1.60 grams of zinc must have reacted to produce this quantity of hydrogen gas.