What is the mass of a sample of O_2 gas, which has a pressure of 741 mmHg, at a

Question

What is the mass of a sample of O_2 gas, which has a pressure of 741 mmHg, at a temperature of 24.0 degree C, in a volume of 255 mL? A gas cylinder contains a mixture of hydrogen (H_2), neon (Ne) and helium (He) gases. If the total pressure of the cylinder is 5.00 atm, and the pressure of H_2 is 2.5. atm and Ne is 880 mmHg then what is the pressure of the He gas inside the cylinder in atm? (760 mmHg = 1 atm) Water is a polar solvent and hexane (C_6H_14) is a nonpolar solvent. Which of the following correctly describes the solubility of the solute?

Explanation / Answer

Solution :-

Q4) Given

Pressure = 741 mmHg * 1 atm / 760 mmHg = 0.975 atm

Temperature = 24 C +273 = 297 K

Volume = 255 ml = 0.255 L

Mass of O2 gas = ?

Using the ideal gas law formula lets first calculate the moles of O2

PV= nRT

PV/RT = n

0.975 atm * 0.255 L / 0.08206 L atm per mol K * 297 K = n

0.0102 mol = n

So the moles of O2 = 0.0102 mol

Now lets convert the moles of O2 to its mass

Mass = moles * molar mass

         = 0.0102 mol *32.0 g per mol

         = 0.326 g O2

So the mass of O2 gas = 0.326 g

Q5) total pressure = 5.00 atm

Pressure of H2 = 2.5 atm

Pressure of Ne = 880 mmHg * 1 atm / 760 mmHg = 1.16 atm

Pressure of He = ?

So the pressure of He = total pressure – ( pressure of H2 + pressure of Ne)

                                       = 5.00 atm – ( 2.5 atm+1.16 atm )

                                       = 1.34 atm

So the pressure of the He gas is 1.34 atm

Q6) polar solute dissolve in polar solvent and non polar solute dissolves in the non polar solvent.

Therefore

Mineral oil is non polar therefore it is not soluble in water

CaCl2 is polar therefore it is not soluble in hexane

NaHCO3 is polar therefore it can be soluble in water

CCl4 is non polar therefore it is not soluble in water

Octane is non polar therefore not soluble in water

So the correct statement is the option C that NaHCO3 is soluble in water

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