A 0.188g sample of unknown metal, X (s), produced 71.4 ml of hydrogen gas when reacted with HCL according to the equation: X(s)+2HCL(aq)--->XCl2(aq)+H2(g)

The gas was collected over water at 23 degrees Celsius. The levels of water inside and outside the gas collecting tube are identical. The vepor pressure of water at 23 degrees Celsius is 21.1 mmHg and the atmospheric pressure is 752 mmHg. Calculate the molar mass of the unknown metal, X. (R=0.0821Latm/molK)

Use PV = nRT to solve for n

P = (752-21.1)/760
V = 0.0714 L
T = 296 K
The equation in the problems tells you that mols H2 equal mols X.
atomic mass X = grams/moles.
My best guess is Zn but you need to do the work. I don't know how close the value is supposed to be but I don't get exactly the atomic mass Zn. Check my work carefully.

Glycerol is a syrup liquid often used in cosmetics and soaps. A 2.50L sample of pure glycerol has a mass of 3.15 x 10 to the 3rd power grams. What is the density in grams per cubic cm

To calculate the molar mass of the unknown metal, X, we need to determine the number of moles of hydrogen gas produced during the reaction.

Step 1: Calculate the pressure of the hydrogen gas collected over water.
The total pressure of the gas collected is equal to the atmospheric pressure. Since the water levels inside and outside the gas collecting tube are identical, the pressure of water vapor at 23 degrees Celsius (21.1 mmHg) needs to be subtracted from the atmospheric pressure (752 mmHg).
P(total) = P(atmospheric) - P(water vapor)
P(total) = 752 mmHg - 21.1 mmHg
P(total) = 730.9 mmHg

Step 2: Convert the pressure of hydrogen gas to atmospheres.
Since the ideal gas law uses units of atm, we need to convert the pressure of the hydrogen gas from mmHg to atm.
P(total) = 730.9 mmHg * (1 atm / 760 mmHg)
P(total) = 0.9614 atm

Step 3: Convert the volume of the hydrogen gas to liters.
The volume of the hydrogen gas collected, 71.4 mL, needs to be converted to liters.
V = 71.4 mL * (1 L / 1000 mL)
V = 0.0714 L

Step 4: Convert the temperature to Kelvin.
The temperature given is 23 degrees Celsius, which needs to be converted to Kelvin using the equation: T(K) = T(°C) + 273.15.
T(K) = 23°C + 273.15
T(K) = 296.15 K

Step 5: Calculate the number of moles of hydrogen gas using the ideal gas law.
The ideal gas law states: 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.
n = PV / RT

Substituting the known values:
n = (0.9614 atm) * (0.0714 L) / ((0.0821 L*atm/mol*K) * (296.15 K))
n ≈ 0.0228 mol

Step 6: Determine the number of moles of metal, X.
According to the balanced chemical equation, one mole of metal, X(s), produces one mole of hydrogen gas, H2(g). Therefore, the number of moles of metal, X, is equal to the number of moles of hydrogen gas produced.
n(X) = 0.0228 mol

Step 7: Calculate the molar mass of the unknown metal, X.
The molar mass (M) is equal to the mass (m) divided by the number of moles (n):
M(X) = m(X) / n(X)

Substituting the known values:
M(X) = 0.188 g / 0.0228 mol
M(X) ≈ 8.246 g/mol

Therefore, the molar mass of the unknown metal, X, is approximately 8.246 g/mol.

To calculate the molar mass of the unknown metal, X, we need to use the following steps:

1. Calculate the pressure of the hydrogen gas collected:

The total pressure inside the gas collecting tube will be the sum of the vapor pressure of water and the pressure exerted by the hydrogen gas. Since the water levels inside and outside the tube are identical, the pressure of the hydrogen gas can be calculated as:

P_H2 = P_total - P_WATER

where P_total is the atmospheric pressure (752 mmHg) and P_WATER is the vapor pressure of water (21.1 mmHg).

P_H2 = 752 mmHg - 21.1 mmHg = 730.9 mmHg

2. Convert the pressure to atm:

To use the ideal gas law, we need to convert the pressure to atm.

P_H2 = 730.9 mmHg * (1 atm / 760 mmHg) ≈ 0.9603 atm

3. Convert the volume of hydrogen gas to moles:

We need to convert the volume of hydrogen gas collected (71.4 mL) to moles using the ideal gas law equation:

PV = nRT

n = PV / RT

where P is the pressure in atm, V is the volume in Liters, R is the ideal gas constant (0.0821 L atm/mol K), and T is the temperature in Kelvin.

First, let's convert the volume to Liters:

V_H2 = 71.4 mL * (1 L / 1000 mL) = 0.0714 L

Now we can calculate the number of moles of hydrogen gas:

n_H2 = (0.9603 atm * 0.0714 L) / (0.0821 L atm/mol K * (23 + 273) K) ≈ 0.00288 mol

4. Calculate the number of moles of the unknown metal, X:

According to the balanced chemical equation, 1 mole of the unknown metal, X, reacts with 2 moles of HCl to produce 1 mole of H2 gas.

So, the number of moles of the unknown metal, X, can be calculated as:

n_X = n_H2 / 1 ≈ 0.00288 mol

5. Calculate the molar mass of the unknown metal:

The molar mass (M) is calculated as the mass (m) divided by the number of moles (n):

M_X = m_X / n_X

First, we need to convert the mass of the unknown metal to grams:

m_X = 0.188 g

Now we can calculate the molar mass:

M_X = 0.188 g / 0.00288 mol ≈ 65.3 g/mol

Therefore, the molar mass of the unknown metal, X, is approximately 65.3 g/mol.