Download CHEM1212 Midterm Questions and Answers Northeastern University and more Exams Chemistry in PDF only on Docsity!
Indicate on the response sheet whether the statement is true (mark A ) or false (mark B ).
- Ultraviolet light has higher energy than infrared. True
False
- Ammonia (NH 3 ) is a strong electrolyte
True
False
- The volume of a fixed amount of gas (at constant P) is proportional to the temperature of the gas. True
False
- A mole of any gaseous species occupies 22.4 L at standard temperature and 760 torr pressure. (2 marks) True
False
- The chemical formula for sulfate is HSO 4 −.
True
False
Indicate the answer choice, on the response sheet , that best completes the statement or answers the question.
- Nitroglycerin detonates according to the balanced reaction:
4 C 3 H 5 N 3 O 9 ( l ) → 12 CO 2 ( g ) + 6 N 2 ( g ) + O 2 ( g )+ 10 H 2 O( g ).
If 3.00 mol of nitroglycerin is detonated, how many L of carbon dioxide (assume all gases at standard temperature and pressure) are released? (2 marks) 101 L
67.2 L
168 L
650 L
- What is the electron configuration of selenium (Se)? 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^104 p^6
1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^10 4p^5
[Kr]4s^2 3d^10 4p^4
[Ar]4s^2 3d^10 4p^4
- According to the valence shell electron pair repulsion theory, which molecule shape best describes the geometry of a carbon in a double bond? Trigonal bipyramidal
Square planar
Trigonal planar
Tetrahedral
- In the context of the modern periodic table, _____ are examples of transition metal elements.
Mo and Pd
Sb and I
Pm and Gd
U and Pu
- Which of the following has the smallest radius?
Br−
Br
Cl−
F
- In an attempt to determine the velocity of a person on a bicycle, an observer uses a stopwatch and times the length of time it takes to cover 35 "squares" on a sidewalk, 6.75 seconds. A measurement of one of the squares shows it to be 1.13 m long. What velocity in km/h, should the observer report? (2 marks) 18.4 km/h
21 km/h
0.352 km/h
21.1 km/h
- Among the following elements, which displays the lowest electronegativity?
Se
Ca
C
F
- What is the partial pressure of hydrogen in a 100.0 L vessel at -10.0°C holding 11.6 g H 2 , 6.8 g Ar, and 5.3 g of He? (2 marks) 1.34 atm
1.24 atm
0.31 atm
0.0367 atm
- If 92.8 grams of magnesium carbonate is dissolved in sufficient water to prepare 2.30 L of water, the resulting solution has a molarity of (2 marks): 0.272 M
0.479 M
0.280 M
0.371 M
- The molecular formula for aluminum phosphate is _____.
Al 3 PO 4
AlPO 4
Al 3 (PO 4 ) 2
Al 2 PO 3
- Which of the following illustrates the balanced reaction of butanol (C 4 H 9 OH) with oxygen to form carbon monoxide
and water? (2 marks) 2 C 4 H 9 OH (l) + 10 O 2 (g) → 8 CO (g) + 5 H 2 O (l)
C 4 H 9 OH (l) + 4 O 2 (g) → 4 CO (g) + 5 H 2 O (l)
C 4 H 9 OH (l) + 4 O 2 (g) → 4 CO 2 (g) + 5 H 2 O (l)
2 C 4 H 9 OH (l) + 6 O 2 (g) → 8 CO 2 (g) + 9 H 2 O (l)
- Phosgene is produced in the reaction of carbon monoxide with chlorine gas:
CO( g ) + Cl 2 ( g ) → COCl 2 ( g )
If the yield of phosgene is 76.0% when the reactants are combined stoichiometrically, what is the minimum mass of CO needed to get 110g of phosgene? (2 marks) 76.0 g
104 g
78.9 g
41.0 g
- Convert the value 38.4 ppm into ppb.
0.0384 ppb
3840 ppb
3.84 x 10^4 ppb
3.84 x 10-4^ ppb
- If an ion contains 17 protons, 20 neutrons, and 18 electrons, the ion is:
(^35) Cl 1 −
(^37) Cl 1 −
(^37) Cl1+
(^38) Ar 1 −
- Which of the following molecules has the least polar covalent bond?
KI
C 2 H 6
Ce(NO 3 ) 3
H 2 O
- A motorist discovers that her auto tire measures 17.5 psi rather than the recommended 35 psi. If the tire’s volume is
assumed constant at 11.6 L and the temperature is 45oF at the filling station, how many moles of air will the motorist need to add to bring the tire to 35 psi? (assume 1.00 atm = 14.7 psi) (2 marks) 1.0 moles
0.40 moles
0.60 moles
1.2 moles
- If the binding energy of an electron in a metal is 3.22 × 10 −^19 J, what frequency of photon is required to liberate it from the atom? (2 marks) 9.68 x 10^14 s-
4.86 x 10^14 s-
2.44 x 10^14 s-
4.86 x 10^15 s-
- Some mercury(Hg) is placed on a balance and its mass is determined to be 44.820 g. When the mercury is then placed in a graduated cylinder that originally contains 11.34 mL of water, the new volume is 14.64 mL. What should the density of mercury be reported as? (2 marks) 13.18 g/mL
13.6 g/mL
14.00 g/mL
13.58 g/mL
- What is the correct electron configuration of gallium?
[Ar]3s^23 d^10 3p^3
[Ar]4s^23 d^10 4p^1
[Kr]4s^1 4p^2
1s^1 2s^2 2p^6 3s^2 3p^63 d^104 s^24 p^3
- Which one of the following compounds has sp^2 hybridization?
C 2 H 4
CH 4
C 2 H 2
V 2 O 5
- The particulate nature of light is represented as quanta of energy, referred to as _____.
photons
protons
electrons
nucleons
- In the given equation, which of the following species is classified as a spectator ion? Pb(ClO 3 ) 2 (aq) + KBr(aq) → PbBr 2 (s) + KClO 3 (aq)
Pb2+(aq)
ClO 4 1−(aq)
K1+(aq)
Br1−(aq)
- A particular pair of human lungs has a volume of 2.0 L when inflated. At this volume (and constant P), the temperature inside the lungs is 98.6°F. If the temperature of the air outside the lungs is 23.0°F, what volume of outside air is being inhaled and warmed? (2 marks) 1.2 L
0.90 L
1.5 L
1.7 L
