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Calculate the mass (in grams) of each sample.?
1.0×1025 O3 molecules
Express your answer to two significant figures and include the appropriate units.
3.11×1019 CCl2F2 molecules
Express your answer to three significant figures and include the appropriate units.
9 water molecule(s)
Express your answer to four significant figures and include the appropriate units.
thx in advance
1 Answer
- lenpol7Lv 75 years ago
Remember the Avogadro Number ( 6.022 x 10^(23)) is the number of atoms/molecules in ONE mole of an element/compound.
For O3( Ozone) 1.0 x 10^25 / 6.022 x 10^(23) = 16.065 moles.
moles = mass(g) / Mr
mass(g) = moles X Mr
mass(O3) = 16.065 / 48 = 0.35 g(grams) ( 2.s.f.)
CCl2F2 (di-chloro-di-fluoro methane)
Moles = 3.11 x 10^19 / 6.022 x 10^23 = 5.164 x 10^-5 = ( 0.00005164) moles.
mass(CCl2F2) = 0.00005164 X (12 + (2 x 35.5) + (2 x 19))
mass(CCl2F2) = 0.00005164 X 121 = 6.25 x 10^-3 g (3 s.f.)
moles(H2O) = 9 / 6.022 x 10^(23) = 1.4945 x 10^-23
mass(H2O) = 1.4945 x 10^-23 X 18 = 2.690 x 10^(-22) g ( 4 s.f.)
