Exam 2 Practice questions

Question 1

A physical change
A) occurs when iron rusts.
B) occurs when sugar is heated into caramel.
C) occurs when glucose is converted into energy within your cells.
D) occurs when water is evaporated.
E) occurs when propane is burned for heat.

Answer 1

D

Question 2

How many grams of Li3N can be formed from 1.75 moles of Li? Assume an excess of nitrogen.
6 Li(s) + N2(g) → 2 Li3N(s)
A) 18.3 g Li3N 
B) 20.3 g Li3N 
C) 58.3 g Li3N 
D) 61.0 g Li3N 
E) 15.1 g Li3N

Answer 2

B

Question 3

What is the formula for zinc chloride?
A) ZnC 
B) Zn2Cl2
C) ZnCl2 
D) Zn2Cl 
E) ZnCl3

Answer 3

C

Question 4

Dioxybenzone is a compound found in sunscreen, and only contains carbon, oxygen, and hydrogen. Analysis of the compound found that it contains 4.92% hydrogen and 26.18% oxygen. The molar mass of the compound is 244.25 g/mol. What is the molecular formula?
A) C12H10O3 
B) C10H8O4 
C) C8H11O5 
D) C14H12O4
E) C16H10O6

Answer 4

D

Question 5

A single covalent bond contains \_\_\_\_\_\_\_\_ of electrons.
A) 0 pairs
B) 1 pair 
C) 2 pairs 
D) 3 pairs 
E) 4 pairs

Answer 5

B

Question 6

Identify the number of bonding pairs and lone pairs of electrons in water.
A) 1 bonding pair and 1 lone pair 
B) 1 bonding pair and 2 lone pairs 
C) 2 bonding pairs and 2 lone pairs 
D) 2 bonding pairs and 1 lone pair 
E) 3 bonding pairs and 2 lone pairs

Answer 6

C

Question 7

Draw the Lewis Structure for CH2Cl2

Answer 7

cl-c-cl surrounded by electrons

h on top and bottom

Question 8

Give the electron geometry (eg), molecular geometry (mg), and hybridization for NH3.
A) eg = tetrahedral, mg = trigonal planar, sp2
B) eg = trigonal pyramidal, mg = trigonal pyramidal, sp3
C) eg = tetrahedral, mg = trigonal pyramidal, sp3
D) eg = trigonal pyramidal, mg = tetrahedral, sp3
E) eg = trigonal planar, mg = trigonal planar, sp2

Answer 8

C

Question 9

How many moles of nitrogen are formed when 58.6 g of KNO3 decomposes according to the following reaction? The molar mass of KNO3 is 101.11 g/mol.
4 KNO3(s) → 2 K2O(s) + 2 N2(g) + 5 O2(g)
A) 0.290 mol N2 
B) 0.580 mol N2 
C) 18.5 mol N2 
D) 0.724 mol N2 
E) 1.73 mol N2

Answer 9

A

Question 10

A 12.39 g sample of phosphorus reacts with 42.54 g of chlorine to form only phosphorus trichloride (PCl3). If it is the only product, what mass of PCl3 is formed?
A) 30.15 g
B) 54.93 g 
C) 140.01 g 
D) 79.71 g 
E) 91.86 g

Answer 10

B

Question 11

Consider the following balanced reaction. What mass (in g) of CO2 can be formed from 288 mg of O2? Assume that there is excess C3H7SH present.
C3H7SH(l) + 6 O2(g) → 3 CO2(g) + SO2(g) + 4 H2O(g)
A) 0.396 g CO2
B) 0.209 g CO2
C) 0.792 g CO2
D) 0.126 g CO2
E) 0.198 g CO2

Answer 11

E

Question 12

Identify the compound with covalent bonding.
A) NaCl 
B) K
C) H2O
D) He
E) S

Answer 12

C

Question 13

Identify the substance that conducts electricity.
A) NaCl dissolved in water 
B) solid NaCl
C) ethanol
D) solid baking soda
E) sugar dissolved in water.

Answer 13

A

Question 14

Which compound has the shortest carbon-carbon bond length?
A) CH3CH3 
B) CH2CH2
C) HCCH
D) all bond lengths are the same

Answer 14

C

Question 15

Determine the electron geometry (eg) and molecular geometry(mg) of BCl3.
A) eg = trigonal planar, mg = trigonal planar
B) eg = tetrahedral, mg = trigonal planar
C) eg = tetrahedral, mg = trigonal pyramidal
D) eg = trigonal planar, mg = bent
E) eg = trigonal bipyramidal, mg = trigonal bipyramidal

Answer 15

A

Question 16

Determine the electron geometry (eg) and molecular geometry (mg) of CO2.
A) eg = tetrahedral, mg = tetrahedral
B) eg = linear, mg = trigonal planar
C) eg = trigonal planar, mg = bent
D) eg = linear, mg = linear
E) eg = trigonal planar, mg = trigonal planar

Answer 16

D

Question 17

Draw the Lewis structure for the molecule CH3CHCHCH3. How many double bonds are in this molecule?
A) one
B) two
C) three
D) four
E) none

Answer 17

A

Question 18

How many molecules of H2S are required to form 79.0 g of sulfur according to the following reaction? Assume excess SO2.
2 H2S(g) + SO2(g) → 3 S(s) + 2H2O(l)
A) 1.48 × 1024 molecules H2S
B) 9.89 × 1023 molecules H2S
C) 5.06 × 1025 molecules H2S
D) 3.17 × 1025 molecules H2S
E) 2.44 × 1023 molecules H2S

Answer 18

B

Question 19

Give the percent yield when 28.16 g of CO2 are formed from the reaction of 4.000 moles of C8H18 with 4.000 moles of O2.
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O
A) 20.00% 
B) 25.00% 
C) 50.00% 
D) 12.50%

Answer 19

B

Question 20

Which should give the least vigorous reaction when dropped in water?
A) Li
B) Na
C) K
D) Rb
E) Cs

Answer 20

A

Question 21

Which one of the following halogen reaction contains a product with covalent bonds?
A) Mg(s) + F2(g) → MgF2(s)
B) C(s) + O2(g) → CO2(g)
C) 2Cu(s) + I2(g) → 2CuI(s)
D) Br2(l) + Cl2(g) → 2BrCl(g) E) V(s) + 2Cl2(g) → VCl4(l)

Answer 21

D

Question 22

Use Lewis theory to determine the chemical formula for the compound formed between Rb and O.
A) RbO
B) RbO2 
C) Rb2O 
D) Rb2O3 
E) Rb3O2

Answer 22

C

Question 23

EXTRA:
Use Lewis theory to determine the chemical formula for the compound formed between Al and F.
A) Al3F2 
B) Al2F3 
C) AlF2 
D) AlF
E) AlF3

Answer 23

E