PAST BOARDS Flashcards
Calculate the mass of the Sun using the fact that the period of the Earth’s orbit around the Sun is 3.156x107 s and its
distance from the Sun is 1.496x1011 m.
1.99x1030 kg
What is the theory in two- or three-dimensional collision to be applied when playing billiards and in order to sink the target ball in the corner pocket?
Where two equal masses undergo a glancing elastic collision.
If the normality of HCl is greater by 10% compared to KOH estimate the normality of the HCL solution when 0.67 grams
of (NH4)2 SO4 is dissolved in water, treated with excess NaOH and the ammonia released is passed through a solution
of 20 ml of HCl. The excess acid solution is titrated using 15.01ml of KOH solution.
0.152 N
A tannery with a wastewater flow of 0.011 m3/s and a BOD5 of
590 mg/L discharges into the Antamok Creek in Benguet. The creek has a 10-year, 7-day low flow of 1.7 m3/s. Upstream
from the tannery, the BOD5 of the creek is 0.6 mg/L. The BOD rate constants are 0.115/day for the tannery and 3.7/day for the creek. The temperature of both the creek and the tannery
wastewater is 20 deg C. Calculate the initial ultimate BOD after mixing.
9.3 mg/L
Number of double bonds in geraniol
2
In a solution supersaturated with CO3-2 and Ca2, what is the
final concentration of Ca+2 per liter of solution at
equilibrium Ksp CaCO3 (s) = 8.30 (use the quadratic formula)?
16.7 mg/L
Tritium (3H) decays by beta emission to 3He with a half-life of 12.26 years. A sample of a tritiated compound has an initial activity of 0.833 Bq. Calculate the number Ni of tritium nuclei in the sample initially, the decay constant k, and the activity after 2.50 years.
4.7x108 nuclei, 1.8x10-9/s, 0.72 Bq
The removal of phosphorus to prevent or reduce
eutrophication is typically accomplished by chemical
precipitation using one of three compounds. Balance the precipitations reactions for each are shown here.
Using lime: Ca(OH)2 + HPO4 = Ca5(PO4)3OH + H2O + OH-
Using alum: Al2(SO4)3 + HPO42- = AlPO4 + H+ + SO42-
Using ferric chloride: FeCl3 + HPO42- = FePO4 + H+ + Cl-
5, 3, 1, 3, 6; 1, 2, 2, 2, 3; 1, 1, 1, 1, 3
Which of the following physical properties differ for each of a pair of enantiomers?
A. Boiling point and melting point
B. Direction of rotation of plane-polarized light
C. Index of refraction
D. Solubility in ethanol
Direction of rotation of plane-polarized light
If the age of the Earth is 1.3x1017 years, what is the
approximate age of the universe?
5 x 10^17 years
A flowing stream has an oxygen deficiency of 6 mg/L. However,
miles downstream the deficiency was reduced to 4 mg/L through
atmospheric absorption. If the stream has a velocity of 2 mph and contains no BOD and other stream conditions are uniform through its length, estimate the oxygen deficit some
35 miles downstream from the original point.
1.46 mg/L
Estimate the number of breaths taken during an average life span.
4 x 10^8 breaths
The free neutron is an unstable particle that decays into a proton. What other particle is formed in neutron decay, and
what is the maximum kinetic energy (in MeV) that it can possess?
electron, 0.78 MeV
Suppose a long-chain polypeptide is constructed entirely from phenylalanine monomer units. What is its empirical formula? How many amino acids does it contain if its molar mass is 17,500 g/mol?
119
On your wedding day your lover gives you a ring of mass 3.80 g. Fifty years later its mass is 3.35 g. On the average, how many atoms were abraded from the ring during each second of your marriage?
8.7x1011
The three naturally occurring isotopes of uranium are 234U
(half-life 2.5x105 years), 235U (half-life 7.0x108 years), and 238U (half-life 4.5x109 years). As time passes, will the average atomic mass of the uranium in a sample taken from nature increase, decrease, or remain constant?
increase
The activation energy for the isomerization reaction of CH3NC in is 161 kJ/mol, and the reaction rate constant at 600 K is
0.41/s. Calculate the Arrhenius factor and the rate constant for this reaction at 1000 K.
4.3x10-3, 1.7x105/s
The Alangilan Barangay Council in Batangas City has asked you to determine whether the discharge of the barangay’s wastewater into the Calumpang River will reduce the DO below
the standard of 5.00 mg/L at Poblacion 5.79 km downstream, or at any other point downstream. The pertinent data are as
follows:
Calculate the dissolved oxygen at Poblacion.
4.77 mg/L
A pail of water is rotated in a vertical circle of radius
1.00 m. What is the minimum speed of the pail at the top of the circle if no water is to spill out?
3.13 m/s
Which of the following functional groups is present in the melamine molecule?
Amine
If one millieCurie is equal to 3.7 disintegrations/second
and the intensity of any radiation decreases with the square of the distance from the source (I1/I2 = d22/d12, calculate the intensity of radiation at the distance of two meters
when the intensity of radiation is 29 millicurie at a one meter distance.
7 mCi
Why does the use of sunglasses with adjustable shading a practical illustration of the Le Chatelier’s principle?
(Silver chloride is the compound used in the glasses, which upon exposure to sunlight produces silver Ag and chlorine
Cl2).
The addition of energy in the form of sunlight drives
the equilibrium to the right and its removal drives the
equilibrium to the left,
Of the following pairs of physical systems, determine the one with the greater chemical potential.
(1A); one mole of H2O (l) at 100.1 degC; or (B); one mole of H20 (g) at 102 degC. (2A); ten grams of Fe at 2 degC or (2B) ten grams of Fe at 36 degC. (3A); 25 liters of air at 1 atm pressure or (3B) the same
amount of air compressed isothermally to 100 atm.
1B, 2A, 3B
An environmental engineering student was very interested in the reaction of the chemical 2,4,6-chickenwire. She went
into the lab and found that 2,4,6-chickenwire degrades in water. During her experiments she collected the data in the following table. Determine if the reaction is zero-, first-
, second-, third-order with respect to the concentration of
2,4,6-chickenwire.
first
An industrial pollutant to a river flowing with a velocity
of 0.5 m/s. At this point in the river, the concentration of the pollutant is 50 ppm. The pollutant follows first order degradation with a rate constant equal to 0.35/hr. What will be the concentration of the pollutant in the river when it reaches a city 12 km from the industrial plant?
4.85 ppm
You are to design a membrane system for the community of Red Bull. The design flow rate is 0.100 m3/s. The temperature of
the water ranges from 50C in winter to 220C in summer. The membrane you have chosen has a maximum TMP of 200 kPa and a resistance coefficient of 4.2x1012 /m. Based on the pilot testing, the operating TMP should be no greater than 80% of the maximum TMP. Determine the required membrane area.
4000 sq m
A chemical analysis has revealed the following composition
for the rain falling on the city of Thule.
1.38 mg/L HNO3
3.21 mg/L H2SO4
0.354 mg/L HCl
0.361 mg/L NH3
What is the pH of the rainwater?
4.12
Define is DNA? RNA?
Deoxyribonucleic acid and ribonucleic acid
A series of measurements of BOD for a sample of river water over several days are tabulated below.
Day BOD (mg/L)
2 70.0
5 102.4
7 111.0
8 114.0
10 118.8
Determine the BOD rate constant and the ultimate BOD
0.36/day, 130 mg/L
Determine the oxidation number of Chromium in CrF63+.
3
Calculate the volumetric flow rate of leachate through a compacted clay liner if the area of the landfill is 21 ha and the liner thickness is 1.3 m. The hydraulic conductivity is 2.5x10-10 m/s. Assume that the head of water is 0.8 m.
2.8 cu. m per d
Predict whether each of the following nuclides is stable or unstable (radioactive). If the nuclide is unstable, predict the type of radioactivity you would expect it to exhibit.
45K, 56Fe, 11Na, 194Tl.
unstable-beta production, stable, unstable-positron
production, unstable-alpha production
A power plant in Benguet is burning coal on a cold clear
January at 8:00 am with a wind speed of 2.6 meters/second
measured at an elevation of 31 meters and an inversion layer with its base founded at a height of 695 meters. The effective height of the stack is 31 meters. Calculate the distance downward wt which the plume released will reach the inversion layer and start to mix downward.
5.82 km
Arrange in increasing level of toxicity 1: heptachlor 2:
dieldrin 3: DDT 4: Arsenic 5: Cr
2 > 1 > 4 > 3 > 5
For each of the following, identify the radiation emitted.
a) Beryllium-10 changes to boron-10
b) Europium-151 changes to europium-151
c) Thallium-195 changes to mercury-195
d) Plutonium-239 changes to uranium-235
beta, gamma, positron, alpha
Glucose is the only carbohydrate compound that the brain can
use for energy. Which pathway is mobilized to supply the
need of the brain during starvation?
gluconeogenesis
In each case, tell whether the bond is ionic, polar covalent, or nonpolar covalent: Br2, BrCl, HCl, SrF2, SiH4, CO, N2, CsCl
nonpolar covalent, nonpolar covalent, polar covalent,
ionic, nonpolar covalent, polar covalent, nonpolar covalent, ionic
Chlorine gas was first prepared in 1774 by C. W. Scheele by
oxidizing sodium chloride with manganese(IV) oxide. The
reaction is
NaCl(aq) + H2SO4(aq) + MnO2(s)
–> Na2SO4(aq) + MnCl2(aq) + H2O(l) + Cl2(g)
4, 2, 1, 2, 1, 1, 2
What is the color of lead chromate?
Yellow
The isotope of an unknown element, X, has a mass number of 79. The most stable ion of the isotope has 36 electrons and forms a binary compound with sodium having a formula of Na2X. Which of the following statements is (are) true?
I. The binary compound formed between X and fluorine will be a covalent compound.
II. The isotope of X contains 38 protons.
III. The isotope of X contains 41 neutrons.
IV. The identity of X is strontium, Sr.
I only
If you had a mole of U.S. dollar bills and equally
distributed the money to all of the people of the world, how rich would every person be? Assume a world population of 7 billion.
90 trillion dollars
Vitamin A has a molar mass of 286.4 g/mol and a general molecular formula of CxHyE, where E is an unknown element.
If vitamin A is 83.86% C and 10.56% H by mass, what is the molecular formula of vitamin A?
C20H30O
Is it possible for an endothermic reaction to have zero activation energy?
No
How many molecules are in one drop of water?
1.7x10^21
Naturally occurring uranium is composed mostly of 238U and
235U, with relative abundances of 99.28% and 0.72%, respectively. The half-life for238U is 4.5x109 years, and the half-life for 235U is 7.1x108 years. Assuming that the earth was formed 4.5 billion years ago, calculate the relative abundances of the 238U and 235U isotopes when the earth was formed.
77% and 23%
What is the pH of a water that contains 120.00 mg/L of bicarbonate ion and 15.00 mg/L of carbonate ion?
9.4
A magnesium hydroxide solution is prepared by adding 10.00 g of magnesium hydroxide to a volumetric flask and bringing the final volume to 1.00 L by adding water buffered at a pH
of 7.0. What is the concentration of magnesium in this
solution? (Assume that the temperature is 25◦C and the ionic strength is negligible).
0.17 M
A landfill with a gas collection system is in operation and
serves a population of 200,000. MSW is generated at a rate
of 1.95 kg · (capita)−1· day−1. Gas is produced at an annual
rate of 6.2 L · kg−1 of MSW delivered to the landfill. The
gas contains 55% methane. Gas recovery is 15% of that
generated. The heat content of the landfill gas is
approximately 17,000 kJ · m−3 (a value lower than the
theoretical value because of dilution of the methane with air during recovery). The landfill company and a developer have proposed to build a subdivision in the vicinity of the landfill and pipe the methane generated to the homes to be used for heating. The homes are estimated to use an average of 110 × 106 kJ of heat energy each year. Peak usage during winter is 1.5 times the average usage. How many homes
can be built in the subdivision?
7 homes
Choose the common methods in the removal of fine particle in hot airstream in cement production.
ESP
Experiments during a recent summer on a number of fireflies
(small beetles, Lampyridaes photinus) showed that the
average interval between lashes of individual insects wa 16.3 s at 21.00C and 13.0 s at 27.80C.What would be the average interval between flashes of an individual firefly
at 30.00C?
12 s
Glycerin is a nonvolatile liquid. What is the vapor
pressure of a solution made by adding 164 g glycerin to
338 mL H2O at 39.88C?
50 Torr
The enthalpy of combustion of CH4(g) when H2O(l) is formed is 2891 kJ/moland the enthalpy of combustion of CH4(g) when H2O(g) is formed is 2803 kJ/mol. Use these data and Hess’s
law to determine the enthalpy of vaporization for water.
44 kJ
A 150.0-g sample of a metal at 75.00C is added to 150.0g H2O at 15.00C.The temperature of the water rises to 18.30C. Calculate the specific heat capacity of the metal, assuming
that all the heat lost by the metal is gained by the water.
0.25 J/g-degC
The best solar panels currently available are about 19% efficient in converting sunlight to electricity. A typical
home will use about 40 kWh of electricity per day. Assuming 8.0 hours of useful sunlight per day, calculate the minimum
solar panel surface area necessary to provide all of a
typical home’s electricity.
25 m^2
The difference between the actual property value of a
solution and the value it would have as an ideal solution at the same T and P and composition is called
Excess
A desalination plant treats sea water with a salt
concentration of 30,000mg-L−1 at a flow rate of 1.5 m3/s−1. The recovery is 70%. The salt rejection is 99.5%. Determine the concentration of salt in the concentrate stream.
99650 mg/L
Some domestic wastewater has 30 mg/L of nitrogen in the form of either organic nitrogen or ammonia. Assuming that very few
new cells of bacteria are formed during the nitrification of the waste (that is, the oxygen demand can be found from a
simple stoichiometric analysis of the nitrification
reactions given above), find the ratio of the ultimate NBOD to the concentration of nitrogen in the waste.
4.6
Suppose that the pressure in an automobile tire is 2.30
atm at a temperature of 20°C. What will the pressure in the tire be if, after 10miles of driving, the temperature of the tire increases to 47°C?
2.51 atm
Given the following data:
(1) 2H2(g) + C(s) → CH4(g) ΔG0 = -51 kJ
(2) 2H2(g) + O2(g) → 2H2O(l) ΔG0 = -474 kJ
(3) C(s) + O2(g) → CO2(g) ΔG0 = - 394 kJ
Calculate ΔG0 for the reaction
CH4 (g) + 2O2 (g) → CO2 (g) + 2 H2O (l)
-817 kJ
Carbon tetrachloride, CCl4, has a vapor pressure of 213 torr at 400C and 836 torr at 800C. What is the normal boiling point of CCl4?
77 degC
A sample of an ideal gas at 15.0 atm and 10.0 L is allowed to expand against a constant external pressure of 2.00 atm at a constant temperature. Calculate the work in units of kJ for the gas expansion.
-13 kJ
Consider the reaction 2O(g) —> O2 (g). Predict the signs of deltaH and deltaS. Would the reaction more spontaneous at high or low temperatures?
deltaH = -, delta S = -, low
A rock contains 0.688 mg 206Pb for every 1.000 mg 238U present. Assuming that no lead was originally present, that all the 206Pb formed over the years has remained in the rock,
and that the number of nuclides in intermediate stages of decay between 238U and 206Pb is negligible, calculate the
age of the rock.
3.8x10^9 years
One of the congeners of toxaphene, a persistent pesticide that was used on cotton, is 1, 2, 3, 4, 7, 7 – heptachloro – 2 - norbornene. The bioconcentration factor for this chemical in fish was determined to be 11 200 L/kg. If the concentration is 1.1 ng/L in Lake Greenway, determine the estimated concentration in fish in micro g/kg.
12.3
If 25.0 ml of 0.200 M NaOH are added to 50.0 ml of 0.100 M HC2H3O2, what is the pH of the resulting solution?
8.8
An organic chemist synthesizes a new compound X with acidic
properties. A 0.7200 g sample requires 30.00 ml of 0.2000 M Ba(OH) for titration. What is the equivalent weight of X?
60
What is the mass of a 50 μCi sample of pure 131I?
4x10^-10 g
What particle is emitted in the decay chain represented by 14^6C →
14^7N?
Beta
Which of the following indicators is used in EDTA titration?
Solochrome, Calmagite, Eriochrome Black T
Determine the stability of the atmosphere given the
following data collected for Tagaytay:
Elevation Temperature
2.10 m 14.40 degC
325.00 m 11.25 degC
-1.02 degrees C per 100 meters
In a dehydration reaction where water is lost, an organic compound C3H8O reacts with concentrated phosphoric acid and
a product is formed. This product rapidly decolorizes a solution of bromine in tetrachloromethane. What is this product?
Propene
The ion that would be isoelectronic with the noble gas xenon is:
I-
The company you work for plans to release a waste stream containing 7 mg/L of benzaldehyde. Calculate the theoretical oxygen demand of this waste stream in mg/L.
17
If a water sample was found to contain 19.2 mg/L of magnesium ion and 44.4 mg/L of calcium ion, expressed the amount of
hardness. The sample case from a Maynilad source.
189 mg/L as CaCO3
The Malayan landfill about 100 kilometers from Kuala Lumpur serves a population of 562,400 people generating MSW at a
rate of 1.90 kilograms per capita per day. The capacity of the landfill is 11.3x106 cubic meters. In 2015, 63% of the landfill was being used. The ratio of cover to compacted fill is 1.95. Calculate the remaining projected life for the landfill. Assume the density of the compacted waste to be 492 kilograms per cubic meters.
2.78 years
The design flow and overflow rates for a settling tank are 0.044 m3 per s and 20 m per day, respectively. Determine the surface area of this tank. Determine the length of the tank, sing conventional wisdom for length-to-width ratios.
Determine the tank depth, assuming a detention time of 2 hours.
190 m^2, 16 m and 1.7 m
In a 30.0-s interval, 500 hailstones strike a glass window of area 0.600 m2 at an angle of 45.0° to the window surface. Each hailstone has a mass of 5.00 g and moves with a speed of 8.00 m/s. Assuming the collisions are elastic, find the average force and pressure on the window.
0.94 N; 1.6 Pa
Fatty acid such as lauric acid and palmitic acid and oleic acid are long unbranched carboxylic acids consisting of 12
to 20 carbon atoms. Which type of fatty acid should people avoid ingesting, saturated or unsaturated and why?
Saturated, because the risk of cardiovascular disease is
increased
Assuming that air at sea level is composed of 20% oxygen and 80% nitrogen, determine the pressure and air composition on top of Mount Everest at 0 ̊C and air altitude of 29143 ft.
0.333bar, yO2=0.177, yN2=0.823
An ideal gas is taken through a Carnot cycle. The isothermal expansion occurs at 250°C, and the isothermal compression
takes place at 50.0°C. The gas takes in 1 200 J of energy from the hot reservoir during the isothermal expansion. Find
(a) the energy expelled to the cold reservoir in each cycle
and (b) the net work done by the gas in each cycle.
740 J, 460 J
A chemical, SpartanGreen, has a partition coefficient of
12,500 (mg · kg−1)(mg · L−1 )−1. If the concentration of this chemical in water is found to be 105 g·L−1, at equilibrium, what is the concentration on the soil?
1330
A 1 500-kg car is moving at 20.0 m/s. The driver brakes to a stop. The brakes cool off to the temperature of the surrounding air, which is nearly constant at 20.0°C. What is the total entropy
change?
1.02 kJ/K
How long will it take for leachate to migrate through a 0.9 m clay liner with a hydraulic conductivity of 1 × 10−7 cm/s if the depth of leachate above the clay layer is 30 cm and the porosity of the clay is 55%?
12 years
How fast are you personally making the entropy of the
Universe increase right now? Compute an order of magnitude estimate.
10^0 W/K
A 1.60-L gasoline engine with a compression ratio of 6.20 has a useful power output of 102 hp. Assuming the engine operates in an idealized Otto cycle, find the energy taken in and the energy exhausted each second. Assume the fuel–
air mixture behaves like an ideal gas
146 kW, 71 kW
Whatever the compound, the gram molecular weight contains the same number of molecules, known as Avogadro’s number. It
is expressed as:
6.02x10^23 particles per mole
Which would make more efficient cold compress, ethanol or methanol?
methanol
A reported synthesis of the transuranium element bohrium (Bh) involved the bombardment of berkelium-249 with neon-22 to produce bohrium-267. The half-life of bohrium-267 is 15.0
seconds. If 199 atoms of bohrium-267 could be synthesized,
how much time would elapse before only 11 atoms of bohrium-
267 remain?
63 s
When a foreign substance is injected in a rabbit, how long does it take to find antibodies against the foreign substance
in the rabbit serum?
1 to 2 weeks
Which of the following objects are chiral (assume that there
is no label or other identifying mark)?
a) Pair of scissors
b) Tennis ball
c) Paper clip
d) Beaker
e) The swirl created in water as it drains out of a sink or
bathtub
chiral, achiral, achiral, achiral, chiral
Applying the Gibbs phase rule in the degrees of freedom,
determine the number of degrees of freedom of
a) liquid water in equilibrium with its vapor
b) liquid water in equilibrium with a mixture of water vapor
and nitrogen
c) a liquid solution of alcohol in water equilibrium with
its vapor
F=1; F=2; F=2
Uranium-235 undergoes a series of alpha particle and beta particle productions to end up as lead-207. How many alpha particles and beta particles are produced in the complete
decay series?
7, 4
Are the following processes exothermic or endothermic?
a) When solid KBr is dissolved in water, the solution gets
colder.
b) Natural gas (CH4) is burned in a furnace.
c) When concentrated H2SO4 is added to water, the solution
gets very hot.
d) Water is boiled in a teakettle.
endothermic, exothermic, exothermic, endothermic
A 150.0-g sample of a metal at 75.0degC is added to 150.0 g H2O at 15.0degC. The temperature of the water rises to 18.3degC. Calculate the specific heat capacity of the metal,
assuming that all the heat lost by the metal is gained by the water.
0.25 J/g-degC
Propanoic acid and methyl acetate are constitutional
isomers, and both are liquids at room temperature. One of
these compounds has a boiling point of 141°C; the other has a boiling point of 57°C. Which compound has a higher boiling point?
propanoic acid
A 0.0722 M acid has pH of 3.11, what is the Ka of the acid?
8.35 x 10^-6
Which Republic Act is the PRC Modernization Act of 2000?
R.A. 8981
Calculate the entropy change if 350 g of water at 50C is mixed with 500 g of water at 700C.
4.49 eu
We heat 50.0 g of an unknown substance by adding 205 cal, and its temperature rises by 7.0°C. Identify the substance.
ethanol
A compact car has a mass of 800 kg, and its efficiency is rated at 18%. Find the amount of gasoline used to
accelerate the car from rest to 27 m/s (60 mi/h). Use the fact that the energy equivalent of 1 gal of gasoline is 1.3x108 J. Suppose the compact car has a gas mileage of 35 mi/gal at 60 mi/h. How much power is delivered to the wheels?
0.013 gal, 11 kW
How many grams of nickel (Il) nitrate hexahydrate must be used to prepare a 200ml solution containing 0.5M nitrate ions? Assume 100% ionization. (Ni-58.69)
a. 14.53g b. 35.41g c. 41.35g d. 53.14g
a. 14.53g
A 30% solution of phosphoric acid
(97.9956) has a specific gravity of
1.18. What is its normality as an acid assuming partial neutralization to HPO4^2-?
a. 3.61N
b. 7.22N
c. 4.82N
d. 9.63N
b. 7.22N
How many mL of 1N AgN03 would be required to precipitate the chloride from 20mL of 0.55N SrCl26H20?
a. 11mL
b. 5.5mL
c. 3.5mL
d. 14 mL
a. 11mL
How much water must be added to 50mL of a 0.4N solution of Cr2(SO4)318H2O in order to
make it 0.05M? The solution is to be used in the precipitation of chromium as the hydroxide.
a. 40mL
b. 62.2mL
c. 16.7mL
d. 25.5mL
c. 16.7mL
An aqueous solution containing 20wt% Kl (166.002) has a density of 1.168g/Ml. Find the molality of the Kl solution.
a. 1.24m
b. 1.05m
c. 1.65m
d. 1.51m
d. 1.51m
The concentration of icosane (282.56) in a particular sample of rainwater is 0.2ppb. What is its molar concentration?
a. 5x10^-10 M
b. 7x10^-10 M
c. 9x10^-10 M
d. 8x10^-10 M
b. 7x10^-10 M
What is the density of 53.4% NaOH (40) if 16.7mL of the solution diluted to 2L gave 0.169M
NaOH?
a. 1.52g/mL
b. 1.32g/mL
c. 0.97g/mL
d. 1.21g/mL
a. 1.52g/mL
How many grams of B(OH)3 (61.83) should be used to make 2L of 0.05M solution?
a. 5.21g
b. 6.18g
c. 3.44g
d. 8.32g
b. 6.18g
Marie Curie dissolved 0.09192g of RaCl2 and treated with excess AgNO3 to precipitate 0.0889g of AgCl. In her time, the atomic mass of Ag was known to be 107.8 and that of Cl was 35.4. Find the atomic mass of Ra from these values.
a. 225.6
b. 225.8
c. 225.3
d. 225.1
c. 225.3
Twenty dietary iron tablet total mass of 22.131g were ground and mixed thoroughly. Then, 2.998g of the powder were dissolved in HNO3 and treated to convert all iron to Fe3+. Addition of NH3 precipitated Fe2O3.xH2O, which was ignited to give 0.264g of Fe2O3 (159.69). What is the average mass of FeS047H2O (278.01) in each tablet?
a. 0.512g
b. 0.339g
c. 0.155g
d. 0.769g
b. 0.339g
A method to measure soluble organic carbon in seawater includes oxidation of the organic materials to CO2 with K2S2O8, followed by a gravimetric determination of the CO2 trapped by a column of ascarite. A water sample weighing 6.234g produced 2.378mg CO2 (44.009). Determine the ppm C in the seawater.
a. 442.5
b. 104.1
c. 612.7
d. 242.1
b. 104.1
The amount of calcium present in milk can be determined by adding oxalate to a sample and measuring the mass of calcium oxalate Precipitated. What is the mass percent of calcium, if 0.429g of calcium oxalate forms in a 125g sample of milk when excess aqueous sodium oxalate is added.
Na2C2O4 (aq) + Ca+2 (aq) CaC2O4(S) + 2Na+ (aq)
Atomic Ms.: Na=23 Ca=40 C=12 O=16
a. 0.11%
b. 0.22%
c. 0.33%
d. 0.44%
a. 0.11%
One pound of a mixture of NaCl and KCI was water treated with sulfuric acid and 1.2lb of potassium and sodium sulfate were recovered. What is the mass ratio of NaCl to KCI in the original mixture?
a 2.14
b. 2.41
c 4.12
d. 4.21
a 2.14
A solid mixture weighing 0.5485g contained only ferrous ammonium sulfate hexahydrate, FeSO4(NH4)2SO46H2O (392.13) and ferrous chloride hexahydrate, FeCl26H20 (234.840). The sample was dissolved in 1M H2S04, oxidized to Fe3+ with H2O2, and precipitated with cupferron. The ferric cupferron complex was ignited to produce 0.1678g of ferric oxide (159.69). Calculate the wt% Cl (35.453) in the original sample.
a. 41.15%
b. 13.7%
c. 64.12%
d. 22.65%
d. 22.65%
Determine the molarity of a solution prepared in the laboratory by dissolving 12.7g of HCI in sufficient water to make 1L of solution. (NOV. 2019)
a. 0.1277M
b. 0.5221M
c. 0.3481M
d. 0.4231 M
c. 0.3481M
Determine the number of moles and grams of N2HP04 in 1.75L in 0.46M of NaHP04 solution. (OCT. 2021)
a. 0.556mol; 85g
b. 0.805mol; 114g
c. 0.46mol; 185g
d. 0.656mol; 90g
b. 0.805mol; 114g
Determine the number of moles of an unknown base in a solution when titrated with 0.15M HCI
and 22.01mL of the acid were needed to reach the end point of the titration. (OCT. 2021)
a. 2.2x10-3ml
b. 1.1x10-3ml
c. 0.9x10-3ml
d. 3.3x10-3ml
d. 3.3x10-3ml
If one gallon of blood was added in three gallons of water, and one ounce of that dilution was added to 9 ounces of water, what is the final dilution when 7mL of that dilution was added to 563mL of water? (OCT. 2021)
a. 5.65X10^-3
b. 2.24x10^-2
c. 1.72X10^-4
d. 3.11 x10^-4
d. 3.11 x10^-4
Determine the final volume of 0.51M KBr when the starter volume is 100mL. From a 50mL solution of
0.25M alanine, what volume will be required using 0.11M alanine? (NOV. 2019)
a. 196mL, 114mL
b. 51mL; 33mL
c. 179mL; 102mL
d. 201mL; 120mL
a. 196mL, 114mL
Define a salt in terms of acid and base. (NOV. 2019)
a. A salt is a compound that follows Le Chatelier’s Principle in reactions with other compounds.
b. All Of these
c. A salt is a compound formed when the nucleus of a hydrogen atom enters a quantity of water.
d. A salt is a compound (other than water) produced by the reaction of an acid and a base.
d. A salt is a compound (other than water) produced by the reaction of an acid and a base.
When a can of soda is opened and C02 is released to the atmosphere, what is the resultant pH of the soda? (OCT. 2021 and MAY 2022)
a. Decreases
b. Increases
c. The same
d. All these
b. Increases
What is the pH Of a 0.035M KOH Solution?
a. 12.54
b. 1.46
c. 3.5
d. 9.97
a. 12.54
