Question

Station 10 The name of rust is iron(III) oxide. If there are 4.35 × 1022 atoms of oxygen in the rust on your bi- cycle, how many grams of rust are on your bicycle? (No numerical measurement needed; just solve the calculation.) Station 11 In this station, you will find a 100 mL graduated cylinder that contains about 23 mL of rubbing alcohol. The chemical formula for rubbing alcohol is C,H,OH and the density is 0.786 g/mL. How many atoms of carbon are in the graduated cylinder?

Answer 1

Rust = Fe_2O_3 (Iron (III) oxide) 4.35 times 10^22 atoms of oxygen. = > 4.35 times 10^22/3 molecules of Fe_2O_3 therefore (as I molecule of Fe_2O_3 has 3 atoms of oxygen) = > Moles of Fe_2O_3 = 4.35 times 10^22/3/6.022 times 10^23 therefore (1 mole has 6.022 times 10^23 units) = 24.078 times 10^-3 moles therefore Fe_2O_3 = 160 g/mol Mass of Fe_2O_3 on bicycle = 24.078 times 10^-3 times 160 = 3.852 g 23 ml of C_3H_7OH (Molar Mass of C_3H_7OH = 60 g/mol) density of C_3H_7OH = 0.786 g.ml Mass = Volume times Density = 23 times 0.786 g = 18.078 g Moles = Mass/Molar Mass = 18.078/60 = 0.301 Moles of Carbon = 3 times 0.301 = 0.903 Number of atoms of Carbon = 0.903 times 6.022 times 10^23 = 5.437 times 10^23 atoms tildeequal 5.44 times 10^23 atoms of Carbon.