Chemistry homework help
Chemistry homework help. Chap’s 6, 7 – atoms, changes and moles
Part I SELECT RESPONSE Write the letter of the best response on the table. (18 pts)
1. What type of ions have names ending in -ide?
A. cations B. anions C. metals D. gaseous
2. When naming a metal ion that can have more than one charge, the numerical value of the charge is indicated by a _____.
A. prefix B. suffix C. Roman numeral D. subscript
3. When naming a covalent compound, the number of atoms of each element present in the molecule is indicated by a _____.
A. prefix B. suffix C. Roman numeral D. superscript
4. What does -ate or -ite at the end of a compound name usually indicate?
A. that there are fewer electrons than protons C. a monoatomic anion
B. the molecules are neutral D. a polyatomic anion
5. Which of the following compounds contains the lead (II) ion?
A. PbCl4 B. PbO C. PbO2 D. PbS2
7. Which element could form an ionic compound with lithium, Li, after electrons are transferred?
A. K B. Fe C. He D. Br
8. In which compound do atoms form bonds by sharing electrons?
A. H2O B. Na2O C. CaO D. MgO
#9-11 A. covalent bond B. ionic bond C. lone pair of electrons D. metallic bond
9. Which term describes a shared pair of electrons between two nonmetal atoms?
10. Which term describes an unshared pair of electron located on an atom?
11. Which term describes the attraction of a cation, typically a metal, with an anion, typically a nonmetal?
12. Which statement best describes why atoms bond?
A. Atoms want to make bonds. B. Bond formation creates a lower energy state.
C. Bonds are needed to build molecules. D. Bond formation creates a higher energy state
13. One mole of which substance contains a total of 6.0 x 1023 atoms?
a. Li b. NH3 c. O2 d. CO2
14. How many carbon atoms are in a 12.01 g charcoal briquette made entirely of carbon, C?
a. 2 b. 12 c. 6.023 x 1023 d. 7.23 x 1023
15. Which amount of helium represents one mole of He atoms?
a. 1 g He b. 6 x 1023 atoms He c. 2 mol He d. 4 L He
16. What unit is used for the coefficients of each molecule in a balanced chemical equation?
a. grams b. molar masses c. moles d. ratio of masses
17. What is the mass in grams of a gold atom ?
a. 3.27 x 10–22 b. 79 c. 197 d. 6.022 x 1023
18. A sample contains 1 mol of Cu and another sample contains 1 mol of Fe. Which statement is true?
a. Both samples have the same number of atoms, since they both contain 1 mol.
b. Both samples have the same mass, since they both contain 1 mol.
c. The Cu sample has a smaller mass, since the atomic mass of Cu is more than that of Fe.
d. The Fe sample contains fewer atoms, since the atomic mass of Fe is less than that of Cu.
Select Response – Answer Table – please write your choices for #1-18 in this table.
1. 5. 9. 13. 17.
2. 6. free, my mistake 10. 14. 18.
3. 7. 11. 15.
4. 8. 12. 16.
Part II Brief Response (26 pt)
20. What term describes a shared pair of electrons between two atoms?
21. What term describes the attraction of a cation with an anion?
22. What term describes the attraction between the particles of any metal?
23. Which term describes a molecule with a symmetrical electron distribution
causing no build-up of charge?
24. What type of bonding is found between molecules in a substance?
25. What is the total number of electrons shared in C2H4?
26. Describe the distribution of charge and the polarity of a CH4 molecule?
27. When is a chemical reaction balanced?
28. In a decomposition reaction, if you begin with a total mass of 5.0 g,
what is the total amount of products formed?
29. What is the law that explains the correct relationship
expressed in #28 above?
30. Give an example of a physical change? Explain why it is a physical change.
31. Give an example of a chemical change? Explain why it is a chemical change.
32. When is a chemical reaction balanced?
Part III Constructed Response (12 pts.)
33. Supply the missing information in each problem. Each problem consists of three parts: 1
st cation/anion and the
number needed to create a neutral compound; 2
nd the formulas of the neutral compound and 3
rd the name.
(A) __Mn4+ + __CN1-
(B) + FeCO3
(C) + magnesium oxide
(D) + nickel (II) acetate
34. Fill-in the blanks with the best response. (2 pts)
(A) What is the name of N2O3?
(B) Write the formula of sulfur trioxide.
35. For each molecule: • draw the Lewis Structure (2 pts. each) total this section – 16 pts
• state the geometry (1 pts. each)
• state the polarity: P or NP (1 pt. each)
(A) PF3 (B) CH3CN
(C) H2CF2 (D) C2H6O
Balance the following chemical reactions, AND write the type of reaction in the blank. (12 pts)
36. __AlCl3 + __HNO3 → __HCl + __Al(NO3)3
37. __H2 + __O2 → __H2O
38. __NH4NO3 → __N2O + __H2O
39. __C4H10 + __O2 → __CO2 + __H2O
40. __ Al + __ HBr → __ AlBr3 + __ H2
41. __MgO + __S8 → __SO2 + __Mg
42. Write the word equation that corresponds to the reaction that is described. (4 pts)
Then convert the word equation into an unbalanced chemical equation
Air bags are inflated when a collision causes an electrical detonator to initiate the decomposition of sodium azide, NaN3.
which forms nitrogen gas, N2, which inflates the air bag, and solid sodium.
Word equation:
Unbalanced equation:
Conversions: Answer the following problems. Show all work and units; use correct significant figures.
43. Calculate the molar mass of methyl amine, CH3NH2. (show the calculation) (2 pts.)
44. How many moles of rust, Fe2O3, are in 17.4 g of Fe2O3? (4 pts.)
45. Consider: 2C2H2 + 5O2 → 4CO2 + 2H2O
How many moles of molecular oxygen, O2, are needed to combust 10.03 moles of acetylene, C2H2? (4 pts.)
46. If a student eats 0.0014 mole of sugar, C12H22O11, how many molecules of C12H22O11 does she eat? (4 p