Question

Calculate the number of atoms in each of the following masses: a. 54.0 g of aluminum ogAlx imetat x 6.022 X 10 atoms Al 26.98gAT imotat = 1.21x102t atoms Al b. 69.45 g of lanthanum (La) c. 0.697 g of gallium d. 0.000 000 020 g beryllium 6) Calculate the mass of the following numbers of atoms: a. 6.022 x1024 atoms of tantalum (Ta) 6022 X 1024 atoms Tax imotta X 6.022 x 1023 abousta 180 95g Ta motta = 1810 gta 1.810x10 gta b. 3.01 x 10atoms of cobalt c. 1.506 x 1024 atoms of argon d. 1.20 x 10" atoms of helium

Answer 1

a) 54 gm of Aluminum • moles = mas molar mass atom x 10cs 4 1 mole = 60022 = 2.00148258 moles - moles of Al- 54 gm 26.98 gmimol . no. of atoms = moles x 6.022 x 1023 = 2:00148258 X 6.022 x 102 = 12.0529 X 1023 atoms = 1·20529 X 1029 (6 69:45 am of lanthanum (La) moles 69.45gm - 138.90547 g/mol = 0.49998031 moles oo noo of oougg 98031 x 6.022x10² atoms = = 3.01088 x 1023 atoms (C) 0.697 gm of gallium 0.697 gm moles = 69.723 gr/mol = g.996701810-3 moles . no. of atoms = 9.9967018163 x 6.022 x 1023 600ZX 1024 atoms 6.02 x 1021 atoms =

(d) Beryllium " moles - - 2x10-8 gm = 0.22192632 8 10 8 moles 9.012 g m/mol " no. of atoms = 6.022 X 1023 x 0.2219 2632 X 158 - 1-3364 xlols atoms 6(a) of tantalum (TQ) 6.022 X 1624 atoms I mole = 6.022 X 123 atoms - 10 moles * moles - 6.022 X 1024 66022X1023 mass of Ta = moless molar mass of Ta Ta Ta= moles y molar mass of - mass of = tem 10 x 180~94788 gm - 18o9.4788 gm =logog x 103 am (b moles of Cobalt = 3.018 16?! 6.022 X 1023 = 0.4 998339 8 10-2 moles i mass of Cobalt = molar mass of Cobalt x moles = 58.933195 gm xo. 49 98 339 X 102 mol = 2904568 X 16-2 gm.

(C) moles of Argon = 1.566 X 1024 6.022 X 1023 = 2050083 moles so mass of Argon = 2050083 mol x 39.948 am mol = 99.9031gm (d) moles of Helium = 1.20 x 1025 60022 X 1023 = 19.92693 moles 4.002602 g/mol mass of He = 19.92693 moles y = 79.75 95 am