PhysChem Quiz

Calculate the root mean square speed (平均二乗速さ), c of a hydrogen molecule at 12 °C, in ms^-1.

• 1895

• 1875

• 1885

• 1865

Determine the temperature where the root mean square speed (平均二乗速さ), c of nitrogen molecules is 4 x 10⁴ cm s^-1.

• 180 K

• 190 K

• 200 K

• 210 K

Find the number of gas molecules that would occupy 23.4 L at a pressure of 5.6 atm and a temperature of 515 ^oC. Assume ideal behavior (理想気体).

• 13.2 x 10²³

• 22.2 x 10²³

• 12.2 x 10²³

• 21.2 x 10²³

0.174 g of H₂ and 1.365 g of N₂ are introduced into a container with volume of 2.83 L and constant temperature of 0 °C. Assume ideal behavior (理想気体).

(a) What is the mole fraction (モル分率) of N₂?

(b) What is the total pressure in the container, in kPa?

• (a) 0.46
  (b) 118.9

• (a) 0.36
  (b) 108.9

• (a) 0.36
  (b) 118.9

• (a) 0.46
  (b) 108.9

At 500 °C, sulphur vapour moves at a root mean square speed (平均二乗速さ) of 0.577 times of SO₂;

while at 860 °C it has the same movement speed as SO₂.

Determine the chemical formula (化学式) of sulphur vapour at 500 °C and 860 °C by finding the molecular weight (分子量) of sulphur vapour at the respective temperatures.

• 500 ^oC: S₆

  860 ^oC: S₃

• 500 ^oC: S₄

  860 ^oC: S₃

• 500 ^oC: S₄

  860 ^oC: S₂

• 500 ^oC: S₆

  860 ^oC: S₂

There is a 0.866 L sample of gas X at a temperature of 301 K and an unknown pressure. The temperature and pressure were changed to 336 K and 31.3 kPa and the new volume was found to be 0.650 L.

(a) What is the initial pressure of the gas, in kPa?

(b) If the gas has a mass of 0.0292 g, identify gas X. Assume there is only 1 type of gas.

• (a) 21.0

  (b) He

• (a) 42.0

  (b) H₂

• (a) 21.0

  (b) H₂

• (a) 42.0

  (b) He

Zinc metal (Zn) reacts with hydrochloric acid (HCl) to produce hydrogen gas (H₂).

Zn_(s) + 2 HCl_(aq) → ZnCl_2(aq) + H_2(g)

Calculate the volume (in litres) of H₂ gas produced from the reaction of 10 g of zinc. Use a pressure and temperature of 1.5 atm and 30°C.

• 2.35

• 1.53

• 2.53

• 1.35

The complete combustion of octane (オクタン) gasoline is represented by the following chemical equation:

2 C₈H_18(l) + 25 O_2(g) → 16 CO_2(g) + 18 H₂O_(l)

Suppose a 15.5-gallon tank of octane gasoline is burned. What is the volume (in m³) of CO₂ produced at 1 atm and 273 K?  

(1 gallon = 3.785 L; density of octane = 0.703 g/mL; molar mass of octane = 114.23 g/mol)

• 44.7

• 74.7

• 54.7

• 64.7

The root mean square speed (平均二乗速さ) of N₂ gas in a container of 1 m³ is known to be c_N2.

If the container is replaced with equal mole of Cl₂ gas at the same pressure, find the root mean square speed of Cl₂ in terms of c_N2.

An ideal gas consisting of only carbon and hydrogen has an empirical formula (組成式) of CH₂. The gas has a density of 3.39 g/L at 25 °C and 120 kPa. What is the molecular formula (分子式) of the gas?

Hint: Molar mass of gas

• C₃H₆

• C₅H₁₀

• C₄H₈

• C₆H₁₂