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1 Carbon atom 2 Oxygen atoms. CO 2. NaNO 3. 1 Na atom 1 N atom 3 O atoms. C 6 H 12 O 6. 6 C atoms 12 H atoms 6 O atoms. The Number of Atoms in a Formula. Carbon Dioxide. Sodium Nitrate. Glucose. continue…. 1 Carbon atom x 12.01 amu = 12,01 amu
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1 Carbon atom 2 Oxygen atoms CO2 NaNO3 1 Na atom 1 N atom 3 O atoms C6H12O6 6 C atoms 12 H atoms 6 O atoms The Number of Atoms in a Formula Carbon Dioxide Sodium Nitrate Glucose continue….. MC 3.2 Formula Mass, Molar Mass, Percent Composition
1 Carbon atom x 12.01 amu = 12,01 amu 2 Oxygen atoms x 16.00 amu = 32.00 amu Total Molecular Mass 44.01 amu CO2 1 Na atom x 22.99 amu = 22.99 amu 1 N atom x 14.01 amu = 14.01 amu 3 O atoms x 16.00 amu = 48.00 amu Total Molecular Mass = 85.00 amu NaNO3 Molecular Mass and Formula Mass Molecular Mass: “ The average mass of molecules compared with the mass of an (Formula Mass) atom of carbon-12 “ Molecular Mass: “ is the sum of all values of atomic masses in a formula unit “ Carbon Dioxide Sodium Nitrate continue….. MC 3.2 Formula Mass, Molar Mass, Percent Composition
1 N x 14.01 amu 5 H x 1.008 amu 1 O x 16.00 amu Formula Mass: 14.01 amu 5.04 amu 16.00 amu 35.05 amu = = = Formula Mass - (Molar Mass) Formula Mass: “ The sum of the atomic masses of all the atoms in its chemical formula “ Calculate the formula mass for ammonium hydroxide: Chemical Formula: NH4OH Use the average atomic mass shown in the Periodic Table continue…. MC 3.2 Formula Mass, Molar Mass, Percent Composition
2 N x 14.01 amu 8 H x 1.008 amu 2 Cr x 52.00 amu 7 O x 16.00 amu Formula Mass: 28.02 amu 8.06 amu 104.00 amu 112.00 amu 252.08 amu = = = = Formula Mass - (Molar Mass) - (cont) Calculate the formula mass of ammonium dichromate: (NH4)2Cr2O7 Chemical Formula: continue…. MC 3.2 Formula Mass, Molar Mass, Percent Composition
1 Cs x 132.91 amu 2 C x 12.01 amu 3 H x 1.008 amu 2 O x 16.00 amu Formula Mass: 132.91 amu 24.02 amu 3.024 amu 32.00 amu 191.95 amu = = = = Formula Mass - (Molar Mass) - (cont) Calculate the formula mass for cesium acetate: Chemical Formula: Cs C2H3O2 continue…. MC 3.2 Formula Mass, Molar Mass, Percent Composition
Atomic mass carbon in compound Total molecular mass 100 = % Carbon x Atomic mass oxygen in compound Total molecular mass 100 = % Oxygen x 1 C x 12.01 amu C 44.01 amu CO2 100 = 27.29 % Carbon x 2 O x 16.00 amu O 44.01 amu CO2 100 = 72.71 % Oxygen x Mass Relationships - Percent Composition Total Molecular Mass 44.01 amu CO2 • Carbon Dioxide What is the percent carbon and percent oxygen in CO2 ? continue….. MC 3.2 Formula Mass, Molar Mass, Percent Composition
1 Na atom x 22.99 amu = 22.99 amu 1 N atom x 14.01 amu = 14.01 amu 3 O atoms x 16.00 amu = 48.00 amu Total Molecular Mass = 85.00 amu 1 Na x 22.99 amu Na 85.00 amu NaNO3 100 = 27.05 % Sodium x 1 N x 14.01 amu N 85.00 amu NaNO3 100 = 16.48 % Nitrogen x 3 O x 16.00 amu O 85.00 amu NaNO3 100 = 56.47 % Oxygen x Mass Relationships - Percent Composition (cont) Sodium Nitrate NaNO3 end….. MC 3.2 Formula Mass, Molar Mass, Percent Composition