Lab Spring18LEE Activities and Due Dates Rec D Quantitative

Lab -Spring18-LEE Activities and Due Dates Rec. D: Quantitative Reactions /27/2018 11:10 AM A 0/15 Calculator -Periodic Table stion 2 of 10 Sapling Learning How many moles of sodium chloride (NaCI) are in 25.1 g of the compound? Number mol O Prevcus Check Answer 0 Nort MacBook Air

Solution

Ans. #1. Moles of NaCl = Mass / Molar mass

                                    = 25.1 g / (58.442468 g/ mol)

                                    = 0.4295 mol

#2. Moles of CS₂ = Mass / Molar mass = 64.7 g / (76.143 g / mol) = 0.84972 mol

# Number of CS₂ molecules = Moles of CS₂ x Avogadro number

                                                = 0.84972 mol x (6.022 x 10²³ molecules / mol)

                                                = 5.1170 x 10²³ molecules

# 1 molecule of CS₂ consists of 3 atoms – (1 C-atom + 2 S-atom)

So,

            Total number of atoms = (3 atoms / molecule) x number of CS₂ molecules

                                                = (3 atoms / molecule) x (5.1170 x 10²³ molecules)

                                                = 1.5351 x 10²⁴ atoms

#3. The three types of information required are-

            A. The number of isotopes that exist for the element

            C. The percentage abundance of each isotope

            E. The masses of the isotopes on the carbon-12 scale.

# The average atomic mass of an element can be given as follow-

Average atomic mass = (% ^xA x its atomic mass) + (% ^yB x its atomic mass) + so on

            Where, x = Atomic mass of ^xA isotope ; , y = Atomic mass of ^yA isotope       and so on.

            % = % abundance of the respective isotopes

            Atomic mass of an isotope is on the relative scale of C-12 mass scale.