General Chemistry Flashcards
Pure aluminum is prepared by the electrolysis of aluminum oxide according to this equation:
(a) Balance this equation.
(b) What mass of aluminum oxide is required to prepare 27 g (1 mol) of
aluminum?
It requires 51 g of Al2O3 to prepare 27 g of Al
A 0.89% w/v NaCl solution is referred to as a physiological or isotonic saline solution because it has the same concentration of salts as normal
human blood, although blood contains several salts and saline solution has only NaCl. What is the osmolarity of this solution?
0.15 M
0.30 osmol
What is the osmolarity of a 3.3% w/v Na3PO4 solution?
0.81 osmol
Is a 0.50% w/v solution of KCl (a) hypertonic, (b) hypotonic, or (c) isotonic compared to red blood cells?
0.067 M
0.30 osmol
hypotonic.
the forward and reverse reactions take place at equal rates, and concentrations do not change.
equilibrium
the change in concentration of a reactant or a product per unit time.
rate of a reaction
What is the pH of buffer solution containing equimolar quantities of
(a) H3PO4 and NaH2PO4?
(b) H2CO3 and NaHCO3?
(a) pH 2.12
(b) pH 6.37
What is the pH of a buffer solution containing equimolar quantities of
(a) NH4Cl and NH3?
(b) CH3COOH and CH3COONa?
(a) 9.25
(b) 4.74
a mathematical relationship between pH, the pKa of a weak acid, and the concentrations of the weak acid and its conjugate base:
Henderson-Hasselbalch
we measure the evolution of gas to determine the rate of reaction. At the beginning of the reaction (at 0 min), 0.020 L of O2 is present. After 15 min, the volume of O2 gas is 0.35 L. What is the rate of reaction?
rate of O2 formation 0.022 L O2/min
What is the pH of a phosphate buffer solution containing 1.0 mol/L of sodium dihydrogen phosphate, NaH2PO4, and 0.50 mol/L of sodium hydrogen phosphate, Na2HPO4?
6.91
In the past, boric acid was used to rinse an inflamed eye. How would you make up 1 L of a H3BO3/H2BO buffer solution that has a pH of 8.40?
0.182 mol of H2BO3 and 1.00 mol of H3BO3 in 1.00 L solution
a linear polysaccharide of as many
as 4000 units of D-glucopyranose joined by
a-1,4-glycosidic bonds
Amylose
What is the pH of a solution made by mixing 0.2 mol of TRIS acid and 0.05 mol of TRIS base in 500 mL of water?
7.7
the reserve carbohydrate of animals, is a highly branched polysaccharide of D-glucopyranose joined by a-1,4-glycosidic bonds and, at branch points, by a-1,6-glycosidic bonds
Glycogen
a highly branched polysaccharide of D-glucose joined by a-1,4-glycosidic bonds and, at branch points, by a-1,6-glycosidic bonds.
Amylopectin
The speed limit in some European cities is 80 km/h. How many miles per hour is this?
50 mi/h
A 335.0 cc sample of urine has a mass of 342.6 g. What is the density, in g/mL, to three decimal places?
1.023 g/mL
If 168 g of an unknown liquid requires 2750 cal of
heat to raise its temperature from 26°C to 74°C,
what is the specific heat of the liquid?
0.34 cal/g C°
A brain weighing 1.0 lb occupies a volume of 620 mL. What is the specific gravity of the brain?
0.732
Shivering is the body’s response to increase the body temperature. What kind of energy is generated by shivering?
kinetic energy
In Japan, high-speed “bullet trains” move with an average speed of 220 km/h. If Dallas and Los Angeles were connected by such a train, how long would it take to travel nonstop between these cities (a distance of 1490 miles)
10.9 hr
Consider butter, density 0.860 g/mL, and sand, density 2.28 g/mL.
(a) If 1.00 mL of butter is thoroughly mixed with
1.00 mL of sand, what is the density of the
mixture?
(b) What would be the density of the mixture if
1.00 g of the same butter were mixed with 1.00 g
of the same sand?
(a) 1.57 g/mL (b) 1.25 g/mL
The maximum speed limit on many roads in the United States is 65 mi/h. How many meters per second (m/s) is this speed?
29 m/s
Convert the speed of sound, 332 m/s to mi/h.
743 mph
The density of titanium is 4.54 g/mL. What is the mass, in grams, of 17.3 mL of titanium?
78.5 g
An unknown substance has a mass of 56.8 g and occupies a volume of 23.4 mL. What is its density in g/mL?
2.43 g/mL
The specific gravity of a urine sample is 1.016. What is its density, in g/mL?
1.016 g/mL
How many calories are required to heat 731 g of water from 8°C to 74°C?
48 x10^3 cal 48 kcal
A 100 g piece of iron at 25°C is heated by adding 230 cal. What will be the final temperature?
46°C
We heat 50.0 g of an unknown substance by adding 205 cal, and its temperature rises by 7.0°C. What is its specific heat?
f 0.59 cal/g °C
It required 88.2 cal to heat 13.4 g of an unknown substance from 23°C to 176°C. What is the specific heat of the unknown substance
0.0430 cal/g deg
What is the mass number of an atom containing:
(a) 15 protons, 15 electrons, and 16 neutrons?
(b) 86 protons, 86 electrons, and 136 neutrons?
(a) The mass number is 31
(b) The mass number is 222
The natural abundances of the three stable isotopes of magnesium are 78.99% magnesium24 (23.98 504 amu), 10.00% magnesium-25 (24.9858 amu), and 11.01% magnesium-26 (25.9829 amu). Calculate the atomic weight of magnesium
24.31 amu
Calculate the percentage of hydrogen and oxygenin water, H2O, and hydrogen peroxide, H2O2.
H2O: H 11.2%, O 88.8%;
H2O2: H 5.9%, O 94.1%
How many protons and how many neutrons does each of these isotopes of radon contain?
(a) Rn-210 (b) Rn-218 (c) Rn-222
(a) Radon-210 has 210 86 124 neutrons.
(b) Radon-218 has 218 86 132 neutrons.
(c) Radon-222 has 222 86 136 neutrons.
Rubidium has two natural isotopes: rubidium-85
and rubidium-87. What is the natural abundance of each isotope if the atomic weight of rubidium
is 85.47?
The abundances are 23.5% for rubidium-87 and 76.5% for rubidium-85.
