TUTORIAL 2.1, 2.2 & 2.3: MOLE CONCEPT

1. Match mole in terms of The mass of C-12 The amount of substance that contain as many elementary particles (atoms as there are atoms in exactly 12.000g of 12C Avogadro’s constant, NA 1 mol of particle contains 6.02 x 1023 particles 2. Calculate the number of moles for: (a) 1.806 × 1022 molecules of nitrogen (b) 10.0 L O2 gas at STP 3. Quinine C20H24N2O2, is a compound extracted from cinchona tree which is traditionally used to treat malaria. If given a 1.08 g of quinine sample, calculate: (a) the molecular mass of quinine. (b) the number of moles of quinine. (c) the number of molecules of quinine. (d) the number of hydrogen atoms. (e) the mass of carbon atoms in gram. 4. A compound consists of 40.0% carbon, 6.71% hydrogen and 53.3% oxygen. What its empirical formula? If the molecular weight of this compound is 180 g determine its molecular formula. 5. The combustion of 11.5 g ethanol (CXHYOZ)produced 22.0 g CO2 and 13.5 g H2O. Determine the empirical formula of ethanol from this experiment. 6. Define the molarity. What is the molarity of the solution, if 15 g NaCl occupy a volume of 75 mL. 7. 8.00 % by mass aqueous solution of ammonia has a density of 0.9651 g Calculate the molarity of NH3.