Which of these is the best definition of a mole?
The relative atomic mass in grams of the substance
The unit for the amount of substance
The number of particles in the relative formula mass in grams of a substance
What is the definition of the Avogadro constant?
6.02 × 1023
The number of particles in one mole of a substance
What is the number of molecules in 23 g of NO2? (Mr of NO2 = 46)
1.204 × 1024
3.01 × 1023
What is the mass of 0.5 mol of HF gas? (Mr of HF = 20)
0.025 g
10 g
40 g
What is the amount of silver atoms in 216 g of silver, Ag? (Ar of Ag = 108)
2 mol
0.5 mol
4 mol
What amount of O2 reacts with 4 mol of Al?
4Al + 3O2 → 2Al2O3
3 mol
What mass of Al reacts with 96 g of oxygen? Mr of O2 = 32 and Ar of Al = 27.
54 g
108 g
27 g
What is a limiting reactant?
The reactant that is present in the smallest mass
The reactant that is left over at the end of the reaction
The reactant that is all used up in a reaction
What is the concentration of a solution formed by dissolving 2 mol of nitric acid in 4 dm3 of solution?
2 mol/dm3
0.5 mol/dm3
8 mol/dm3
What is the volume of 250 cm3 of solution in dm3?
0.250 dm3
0.025 dm3
2.5 dm3