# Chemistry Chapter 6

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1. The sum of the atomic masses of all the atoms in a molecule.
Molecular Weight
2. What is the molecular weight of CO2?
CO2: 1 C (12.01 amu) + 2 O (2 x 16.00 amu) = 44.01 amu
3. The number of atoms in exactly 12 g of 12C. Number of atoms in 1 atomic mass of an element in grams.
A mole (abbreviated: mol)
6.022 x 10E23
5. A _________ of anything always represents 6.022 x 1023 of that thing.
Mole
6. What is one mole of an element?
• The atomic mass expressed in grams; different for each element.
• ex. 1 mole of Na = mass of 22.99 g, 1 mole of Si = mass of 28.09 g.
7. How many Na atoms are there in 5 moles of Na?
• A conversion factor between mass and numbers of things
• (allows us to count atoms by weighing)
• 5 moles Na x 6.022 x 10E23/1 mole Na
8. What is the mass of one sodium atom?
22.98 23 amu
9. What is the mass of one mole of sodium atoms?
23 grams
10. 2 moles of sodium contains how many sodium atoms?
2 x 6.002 = 1.204 x 10E24
11. How many total atoms are there in one molecule of dinitrogen pentoxide
N2O5 = 7 atoms
12. How many atoms are there in 1 mole of dinitrogen pentoxide?
7 x 6.002 = 42.154 = 4.22 x 10E24 atoms
13. What is the proper unit for molar mass?
g/mol
14. What is the molar mass of oxygen?
O2, 1-O = 15.99, O = 16g, O x 2 = 32g, Answer: 32.00g/mol
15. Calculate the molar mass of sodium chloride.
NaCl, Na = 22.989 Cl = 35.452, 23 so 23.00 + 35.45 = 58.45g/mol
16. What is the molar mass of calcium hydroxide?
Ca(OH)3, Ca = 40.08, H = 1.01 x 2 = 2.02, O = 16.00 x 2 = 32.00, add all to = 74.10g/mol
17. A sample of carbon dioxide has a mass of 220.05 grams. How many moles of carbon dioxide are present in the sample?
C = 12.01 x 1, O = 16.00 x 2 = 32.00, adds up to 44.00. 220.05g/ 44 = 5 moles.
18. _____________ compounds chemical formula represents a _____________ unit
Molecular, discrete molecular (e. g. CO2)
19. _____________ compounds chemical formula represents a _____________ unit
Ionic, formula (the whole number ratio of cations to anions; e. g. K2SO4)
20. The mass of one mole (6.022 × 1023 molecules or formula units) is referred to as the ________ ______ of the compound
molar mass, (formula mass expressed in grams) ex: 44.0 g of CO2 = molar mass of CO2 and is the mass of 6.022 × 10E23 molecules of CO2
21. _______ ____________ is the number of moles of each of the elements that make up the compound
Mole composition, CO2 - one mole of C and two moles of O
22. ________ ____________ is the mass of each element in the compound
Mass composition, CO2 = 12.0 g of C and 32.0 g of O
23. Percent composition of a compound
• Mass of each element represented as a percentage of the mass of the entire compound
• Ex: 100 g of NH3, there are 82.0 g of N therefore, the mass percentage of N is 82.0% N
24. Chemical formula - _____________ _______Indicates the number of moles of atoms of each element present in one mole of a substance.
Macroscopic View, In one mole of P2O5, two moles of phosphorus and five moles of oxygen are present.
25. Chemical formula - _____________ _______ the numerical subscripts in a chemical formula give the number of atoms of the various elements present in 1 formula unit of the substance.
Microscopic View, In one molecule of P2O5, two atoms of phosphorus and five atoms of oxygen are present.
26. Which of the following is closest to the average mass of one atom of copper? a. 63.55 g b. 52.00 g c. 58.93 g d. 65.38 g e. 1.055 x 10E-22 g
e. 1.055 x 10E-22, 63.55g divided by 6.022 x 10E23 = 1.055 x 10E-22 g Cu
 Author: Hildymama1 ID: 50190 Card Set: Chemistry Chapter 6 Updated: 2010-11-17 17:54:31 Tags: Chapter Chemistry Quantities Mass Atom Formula Mass Folders: Description: Chapter 6 Quantities in Chemistry Show Answers: