Take this Quiz: A-Level Chemistry: Amount of Substance | Zestly

Question 1

A sample of 0.250 mol of an ideal gas is contained in a vessel with a volume of 5000 cm3 at a temperature of 27 °C. Calculate the pressure of the gas in kPa using the ideal gas equation $pV = nRT$ (where $R = 8.314 	ext{ J K}^{-1} 	ext{ mol}^{-1}$).

Accepted Answer

124.7 kPa

Question 2

Which of the following statements correctly describe the relationship between the Avogadro constant and the mole?

Accepted Answer

The Avogadro constant represents the number of particles in one mole of any substance.

Question 3

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is its empirical formula?

Accepted Answer

CH2O

Question 4

In a titration, 25.0 cm3 of 0.100 mol dm-3 NaOH reacts exactly with 20.0 cm3 of H2SO4. What is the concentration of the H2SO4 solution? The equation is H2SO4 + 2NaOH -> Na2SO4 + 2H2O.

Answer

0.040 mol dm-3

Answer

0.050 mol dm-3

Answer

0.080 mol dm-3

Answer

0.0625 mol dm-3

Question 5

Which factors contribute to a low percentage yield in a chemical synthesis?

Answer

Reversible reactions that do not reach completion.

Answer

Loss of product during transfer or filtration.

Answer

The use of an excess of one reactant.

Answer

Side reactions producing unwanted by-products.