HW 5, CH140 (92 pts)
1. Cinnamon donuts weigh 96 g/dozen. Chocolate-frosted donuts weigh 120 g/dozen. Boston cream donuts weigh 144 g/dozen. How many dozen donuts are in 900 g of each type? (3 pts)
2. in problem 3 explain why the same mass of each donut has different numbers of donuts. (2 pts)
3. How many particles are in a Mole? (1 pt)
4. Describe in words what atomic mass represents. Why is atomic mass so critical to chemistry? (2 pts)
5. A sapphire is composed of aluminum oxide (Al2O3). They are 52.9% Al and 47.1% O. The largest sapphire ever found weighed 42 kg. How many moles of Al and O are in that sapphire? How many of each atom are there in this sapphire? (3 pts)
6. 1×1011 Xe Atoms are placed on an atomic scale as shown below. A. How many moles of Xe are there? B. What mass (in grams) will the scale read? (2 pts)
1×107 Xe Atoms
_____Mol Xe Atoms
_____g Xe
7. Suppose you have 100% pure 235U (ie no other isotopes present). If you have 1×107, 235U A. How many moles of 235U are there? B. What is the mass (in grams) of 235U? (2 pts)
8. (6 pts) Iodine (I) has 2 natural isotopes 127I and 129I. How many moles AND how many atoms of Iodine are in 10 g of:
A. NATURAL iodine (containing both isotopes)
B. Pure 127I
C. Pure 129I
9. A. What causes electronegativity differences between different elements? B. How does electronegativity vary across groups and periods of the periodic table? Which element is most electronegative and which is least? (5 pts).
10. What are anions and cations? (2 pts)
12. Explain what an ionic bond is. (2 pts)
13. Explain what a covalent bond is. Why do we still define 1 atom a cation and the other an anion? (4 pts)
14. Name the following ionic compounds (10 pts)
A. LiF B. Li2CO3 C. NaI D. Be(OH)2 E. HCl F. BaBr2 G. Ra(NO2)2 H. CsCl2 I. Mg3(PO4)2 J. Ca(SO4)
15. Name each of the following covalent compounds (10 pts)
A. SiO2 B. CBr4 C. BF3 D. SF2 E. H2O F.PCl3 G.Se3N2 H.NF3 I.SO2 J. SiS2
16. Calculate the molecular weight for each of the following compounds (be sure to include the units)
(10 pts)
A. H2O B. NaNO3 C. B12C3 D. C6H6 E. C6H12O6 F. NaF G.S8 H. SiCl4 I. Fe(OH)2 J. SF6
17. How many moles of molecules are in 5g of methylphenyl ether (C7H8O)? (2 pts)
18. How many molecules are there in 5g of methylphenyl ether (C7H8O) (2 pts)?
19. Ibuprofen (aka 2-(4-isobutylphenyl) propionic acid) has a molecular formula (C13H18O2).
A: How many moles of aspirin are in 400 mg of Ibuprofen?
B: How many molecules of aspirin are in 400 mg of Ibuprofen? (4 pts)
20. Psilocybin is a psychoactive compound produced by more than 200 species of fungi. It is a small molecule composed of carbon, hydrogen, nitrogen, oxygen and phosphorous and has the chemical formula C12H17N2O4P.
A. How many moles of psilocybin are in 25 mg of the compound? B. How many molecules of psilocybin in a 25 mg sample of the compound? C. How many moles of each element are in a 25 mg sample of psilocybin? How many atoms of each element are there in the sample? (8 pts)
21. Read the article “Definition of the mole (IUPAC Recommendation 2017)” and answer the following questions. (5 pts)
A. What was the early definition of the meter developed by the French?
B. In 1889 the General Conference on Weights of Measures (CGPM) commissioned a meter rod made of the following alloy.
C. What element was used as the source of light as the standard for the meter?
D. What shortcomings does the Kg cylinder standard have and how does this affect the accuracy of the mole?
E. According to the IUPAC definition How many exact elementary entities are in Avogadros number
22. Read the article “Redefining the Mole” and answer the following questions.(7 pts)
A. Why does uncertainty in the kilogram ingot in France affect the definition of the mole?
B. What did the modern scientific community want to replace the platinum-iridium ingot with?
C. Why is Amodeo Avogadro honored with naming the mole Avogadros number?
D. What piece of equipment did Savelas Rabb use to the isotopic purity of silicon and briefly describe how it works.
E. What fundamental constant are they tying define the mole with, instead of the platinum-iridium ingot.
F. What was x-ray interferometry used for?
G. Savelas Rabb used what chemical instead of sodium hydroxide to dissolve the silicon for use in the mass spectrometer?
Last Completed Projects
| topic title | academic level | Writer | delivered |
|---|