Unit 3 Flashcards
Air bags in cars inflate when an electrical spark activates sodium azide (NaN3), so that it decomposes to sodium metal and nitrogen gas. In the balanced reaction equation, how many moles of N2 gas are formed for each mole of NaN3?
a. 1 d. 3 b. 1.5 e. 2.5 c. 2
b.
1.5
The average adult exhales about 1.0 kg of carbon dioxide from the “burning” of sugar each day (the metabolism of sugar is analogous to a combustion reaction). How many kg of glucose (C6H12O6, 180 g/mol) must be consumed to make this quantity of carbon dioxide?
a. 3.8 kg d. 0.68 kg b. 4.1 kg e. 0.18 kg c. 0.43 kg
d.
0.68 kg
Calcium hydride (CaH2, 42.10 g/mol) is so reactive with water (18.02 g/mol) that it can be used to remove traces of water from nonaqueous solvents. What mass of the excess reactant will be left over if 24.6 g CaH2 is added to a large volume of solvent that contains 14.0 g H2O? CaH2(s) + 2H2O() Ca(OH)2(s) + 2H2(g)
a. 8.24 g CaH2 will be left over. d. 3.45 g H2O will be left over. b. 5.26 g H2O will be left over. e. Both are completely consumed. c. 16.4 g CaH2 will be left over.
a.
8.24 g CaH2 will be left over.
A mass of 11.60 g of phosphoric acid (98.00 g/mol) was produced from the reaction of 10.00 g of P4O10 (283.9 g/mol) with 12.0 g water (18.02 g/mol). What was the percent yield for this reaction?
a. 78.62% d. 84.00% b. 101.1% e. 52.70% c. 92.70%
d.
84.00%
Han purple, a synthetic inorganic pigment developed in China in ancient times, has the chemical formula BaCuSi2O6. What is its percent by mass silicon?
a. 18.0% d. 38.9% b. 15.9% e. 7.96% c. 27.2%
b.
15.9%
- Use the following information to decide which reactant is in excess, and how much is left over (assuming 100% yield): 98.0 g B2O3 (69.62 g/mol) and 125 g HF (20.01 g/mol) are allowed to react.
B2O3(s)+ 6 HF(aq) 2 BF3(g)+ 3 H2O
a. Neither is in excess, they react stoichiometrically. b. B2O3 is in excess, 72.5 g remain. c. B2O3 is in excess, 25.5 g remain. d. HF is in excess, 28.2 g remains. e. HF is in excess, 7.34 g remains.
c. B2O3 is in excess, 25.5 g remain.
A 0.3400 g sample of a carboxylic acid is burned in oxygen producing 0.6062 g of CO2 and 0.2496 g of H2O. Determine the empirical formula of the carboxylic acid.
a. C7H14O2
b. C3H6O2
c. C2H5O
b. C3H6O2
The molecular weight of a gas that has a density of 7.10 g/L at 25.0°C and 1.00 atm pressure is __________ g/mol.
a. 68.8
b. 174
c. 56.2
d. 14.6
e. 128.0
b. 174
How many He atoms are found in a party balloon with 2 L volume on a warm day at the North Pole (T=0°C)? The North Pole is at sea level.
a. 5 x1024
b. 5 x 1022
c. 12x1023
b. 5 x 1022
Under similar conditions, which of the following gases would be predicted to behave less like an ideal gas than the others?
a. Ar
b. NH3
c. CH4
d. H2
e. O2
b. NH3
- For equal amounts of molecules at the same pressure and temperature, which compound has the narrowest distribution of molecular speeds?
a. CO2
b. SO2
c. C3H8
b. SO2
- The pressure in a balloon filled with 3 L of gas at STP is decreased by ½ while the volume and number of moles remain constant. What is the new temperature inside the balloon?
a. -136 C
b. 273 C
c. 0 C
a. -136 C
Dispersion forces are due to __________
a. permanent dipoles. d. ionic interactions. b. temporary dipoles. e. protons. c. hydrogen bonding.
b.
temporary dipoles.
Which of the following solvents could involve ion–dipole interactions with Na+? a. benzene (C6H6) d. cyclohexane (C6H12) b. carbon tetrachloride (CCl4) e. pentane (C5H12) c. chloroform (CHCl3)
c.
chloroform (CHCl3)
Which of the following compounds is the most soluble in water?
a. CH3(CH2)2O(CH2)2CH3 b. CH3(CH2)3O(CH2)2CH3 c. CH3OCH3 d. CH3CH2OCH2CH3 e. CH3(CH2)3O(CH2)3CH3
c. CH3OCH3
Which of the following pairs are likely to be miscible?
a. Br2 and benzene (C6H6) b. CH3CH2OCH2CH3 and CH3COOH c. C6H12 (cyclohexane) and hexane CH3(CH2)4CH3 d. CS2 (carbon disulfide) and CCl4 (carbon tetrachloride)
c. C6H12 (cyclohexane) and hexane CH3(CH2)4CH3
Which of the following compounds has the lowest boiling point?
a. CH4 b. CH3Cl c. CH2Cl2 d. CHCl3 e. CCl4
a. CH4
