Chem 127: final review (quiz questions)
Which symbol, often found in chemical equations, indicates that a substance is dissolved in water? a. (w) b. (l) c. (aq) d. (d) e. (Δ)
(aq)
how many scientific calories are equivalent to one nutritional/food calorie?
1 kcal = 1000 C
the area of Africa is approximately 11.7 million square miles. which of the following is the correct way to express this number in scientific notation? a. 1.17 x 10^5 b. 1.17x 10^6 c. 1.17 x 10^7 d. 1.17 x 10^8
1.17 x 10^7 (11,700,000)
given the calculation: 15.21/8.16= 1.8639705882, what is the answer reported to the correct number of significant figures? a. 1.863970 b. 1.8640 c. 1.86 d. 1.77
1.86
consider 1.00 L of air in a patient's lungs at 37C (310K) & 1.00 atm pressure. what volume would this air occupy if it were at 25C (298K) under a pressure of 5.00x10^2 atm (a typical pressure in a compressed air cylinder)? a. 1.35x10^-3 L b. 480 L c. 2.08x10^-3 L d. 1.92x10^-3 L e. 374 L
1.92x10^-3 L p1v1/t1 = p2v2/t2 1Lx1atm/310K = V2x500atm/298K
Diamond is a pure form of the element carbon. If a 2 carat diamond has a mass of 0.396 g, how many carbon atoms are contained in this diamond? a. 3.97 x 10^22 atoms b. 6.58x10^-25 atoms c. 1.99x10^23 atoms d. 1.99x10^22 atoms e. 2.38x10^23 atoms
1.99x10^22 atoms carbon atomic weight = 12g per mole 0.396g x 1mole/1g x 6.022x10^23/12mole =1.99x10^22 atoms *cross out g/mole*
the standard metric unit of volume, the liter, is equal to which of the following? a. 1 cm^3 b. 10 cm^3 c. 100 cm^3 d. 1000 cm^3
1000 cm^3
how many kilometers (km) are there in 1 millimeter (mm)? (*1mm=____km?) a. 1x10^-12 b. 1x10^-6 c. 1x10^6 d. 1x10^12
1x10^-6 (k.h.d.b.d.c.m)
an unknown compound has a mass of 56.8 g and a volume of 23.4 mL. what is the density of this unknown substance? (D=M/V........56.8g/23.4mL) a. 0.411g/mL b. 2.34g/mL c. 2.43g/mL d. 2.50g/mL
2.43g/mL
500ml of 10M HCl is diluted to a final volume of 2L. what is the final concentration? (M1V1=M2V2) a. 40M b. 5M c. 2.5M d. 1.25M e. 0.625M
2.5M 10Mx500mL/2000mL=M2x2000mL
what is the volume occupied by one mole of helium at 0C and 1 atm pressure? a. 1.0 L b. 22.4 L c. 4.0 L d. 40.0 L e. 12.2 L
22.4 L
in one second, light travels 2.998 x 10^8 meters. which of the following is the correct way to write this speed (velocity) in conventional notation? a. 0.00000002998 m/s (^-#) b. 2,998,000 m/s c. 299,800,000 m/s d. 2999,800,000,000 m/s
299,800,000 m/s (move -->x8)
Which notation properly indicates how two molecules of diatomic oxygen would be represented in a chemical equation? a. (O₂)₂ b. O4 c. 2O₂ d. O₂O₂ e. any of the above notations can be used
2O2
a sample of oxygen occupies 1.00 L/ if the temperature remains constant, and the pressure on the oxygen is decreased to one third the original pressure, what is the new volume? a. 3.00 L b. 1.50 L c. 0.667 L d. 0.500 L e. 0.333 L
3.00 L tripling the temperature, which gives you 819k (273x 3=819) increases the volume by a factor of 3 so: 1.00L/ 273k= volume/ 819k so the volume = 3.00l
what is the normal body temperature (98.6F) in Kelvin? (f=1.8C+32, C=K-273) a. 37.0 b. 98.6 c. 3.10x10^2 d. 22.8
3.10x10^2 c=1.8(98.6-32)=37C & k=37+273=310..... 3.10x10^2
how many valence electrons does a carbon atom have? (look a group # on periodic table) a. 12 b. 6 c. 4 d. 1 e. 0
4 (Gp=4A)
methonal (Ch3OH) is the fuel used by race cars in the Indianapolis 500. it burns in the engine according to the equation below. how many moles of oxygen gas are necessary to react completely with 12.5 L of methanol? (density Ch3OH, 0.7910g/mL; Molar mass: 32.05 g/mol) 2CH3OH(l) +3O2(g) --> 2CO2(g) +4H20(g) a. 0.462 mol b. 2.16 mol c. 463 mol d. 740 mol e. 1850 mol
463 mol
1 mole of anything contains Avogadro's number of that thing. what is the numerical value of Avogadro's number? a. 6.022 x 10^-23 b. 1.00 x 10^-14 c. 12.01 d. 1.661 x 10^-24 e. 6.022 x 10^23
6.022 x 10^23
a gas sample is prepared in which the components have the following partial pressures: nitrogen, 555 mmHg; oxygen, 149 mmHg; water vapor, 13 mmHg; argon 7 mmHg. what is the total pressure of this mixture? a. 760 mmHg b. 724 mmHg c. 1480 mmhg d. 386 mmhg e. 614 mmhg
724 mmHg (add all)
what is the mass (g) of 4.00 moles of helium (1), the gas used to fill party balloons? a. 4 amu b. 4.00 g c. 8.00 g d. 16.0 g e. 2.41 x 10^24 g
8.00 g 4 moles x 4 g/1 mole = 16g
an apartment in paris has an area of 80.0 square meters. a ny apartment with which of the following areas is the closet in size? [1meter=1.094 yards; 1 yard=3feet] a. 7.43 square feet b. 290 square feet c. 862 square feet d. 860 square feet
862 square feet 80.0m^2 x (1.094y/1m)^2 x (3ft/1y)^2=861.7 ft^2
Americium-241 is an isotope used in smoke detectors. what is the subatomic composition of a neutral atom of ^241Am? a. 241 p, 95 n, 241 e b. 241 p, 95 n, 146 e c. 95 p, 146 n, 95 e d. 95 p, 146 n, 51 e e. 95 p, 241 n, 95 e
95 p, 146 n, 95 e (Am=95p&e, 241-95=146n)
the very small amount of ozone in the stratosphere blocks a large percentage of cosmic ultraviolet radiation from hitting the earth- yet another reason life exists here as we know it. tropospheric ozone is a primary compound of smog, showing how something can be both good & bad. which of the following Lewis structures represent resonance forms of ozone O3?
:::O---O:___---O:: (18) ::O___---:O---::: (18)
which of the following is always necessary for a chemical reaction to occur between two reactants, A & B?
A & B must collide with sufficient energy and the proper orientation
Upon mixing a clear colorless BaCl2 solution with a clear, colorless Na2SO4 solution according to the reaction below, a student observes a white cloudiness form. What is responsible for the cloudiness that is observed? BaCl2(aq) + Na2SO4(aq) → BaSO4(s) + 2NaCl(aq) a. NaCl b. BaSO4 c. BaCl2 d. Na2SO4 e. it is impossible to tell without doing the reaction
BaSO4 (s) = (cloudy)
A molecule of deoxyribose, an essential part of DNA, contains five carbon atoms, ten hydrogen atoms, and four oxygen atoms. How would the formula of deoxyribose be represented? a. 5C10H4O b. C5H10O4 c. C5H10O4 (lower #s) d. C^5H^10O^4 e. all formulas are acceptable
C5H10O4 (lower #s)
a certain compound has a very high melting point and when it dissolves in water the solution conducts electricity. which one of the following compounds wound have these properties? (ionic compound) a. O2 b. Cr c. CCL4 (m+m) d. Na2SO4 (m+m) e. He (noble gas)
CCL4 (m+m)
which of the following elements is most likely to form a 2+ ion? (look at group # on periodic table) a. Li (+1A) b. K (+1A) c. Al (+3A) d. N (-3A) e. Ca (+2A)
Ca (+2A)
what is the formula of the ionic compound formed when ions of calcium and nitrogen combine? a. CaN b. CaN2 c. Ca2N d. Ca3N2 e. Ca2N3
Ca3N2 (2a+5a=+/-6)
Identify the oxidizing agent and the reducing agent in the reactants of a chemical reaction. Cl2(aq) + 2I-(aq) --> 2Cl-(aq) + I2(aq) 0 -2 -2 0 a. Cl2 is the oxidizing agent and I- is the reducing agent b. I- is the oxidizing agent and Cl2 is the reducing agent c. Cl- is the oxidizing agent & I2 is the reducing agent d. I2 is the oxidizing agent anf Cl- is the reducing agent e. Cl2 is the oxiding agent and Cl- is the reducing agent
Cl2 is the oxidizing agent and I- is the reducing agent Cl 0 --> -2 (reduction=gains electron) I -2 --> 0 (oxidation=loses electron)
what is the precipitate(solid) that forms when solutions of Na3PO4 and Fe(NO3)3 are mixed? (separate them and criss-cross them & look on chart) a. NaNo3 b. NaFe c. FePO4 d. PO4NO3 e. Fe3PO4
FePO4 (solid) Na+ PO4^3- Fe^2+ NO3^-
hydrosulfuric acid or sulfhydric acid is a solutions of hydrogen sulfide in water. which properly represents the Lewis structure of hydrogen sulfide, H2S?
H----:S:---H H=1Ax2 S=6A total =8
which of the following is not a unit for measuring pressure? a. Pa b. Kj (measure energy) c. atm d. mmHg e. torr
Kj
which of the following elements has the lowest ionization energy? (not love e=lower left corner) a. Li b. B c. O d. F e. Ne
Li
which statement correctly describes what happens in the reaction shown below? 2Mg(s)+ S2(g) --> MgS(s) a. Mg is oxidized b. S2 loses electrons c. MgS is the reducing agent (product) d. Mg is the oxidizing agent (product) e. MgS gains electrons(reducing agent)
Mg is oxidized Mg= 0-+2 (lose e= oxidized)
which of the following atoms has the biggest size (radius)? (Biggest=lower left corner) a. Na b. Al c. Cl d. Rb e. I
Rb
which is the Lewis symbol of the fluoride ion?
[F}- with 8 dots
the unbalanced equation for the combustion of octane, a component of gasoline, is shown below. what is the coefficient of carbon dioxide when the equation is balanced? ____C8H18 (l) +____O2(g)--> ___CO2 (g) + ____H2O(l) a. 2 b. 25 c. 16 d. 18 e. no coefficient would be shown
__2__C8H18 (l) +_3/8___O2(g)--> _8__CO2 (g) + ___9_H2O(l) (x2) =16
which of the following is true concerning colligative properties? a. a contaminated solvent has its mp lowered & bp elevated b. a contaminated solvent has its bp lowered & mp elevated c. salt water boils at a temp lower than 100C d. an elevated bp means your sample is not what you think it is e. all the above
a contaminated solvent has its mp lowered & bp elevated * contaminate tries to stay as liquid* FP/MP=0C BP=100C
what term describes a solution of a compound in water that does not conduct an electric current? a. amorphous solution b. an electrolyte solution c. a nonelectrolyte solution d. superconducting solution e. isoelectric solution
a nonelectrolyte solution
sarin is a chemical weapon. considering the physical properties of sarin shown below, which statement about sarin is true? BP = 158C MP = -56C a. a sample of sarin at 0C exists as a solid b. a sample of sarin at room temperature (22C) exists as a gas c. a sample of sarin at -100C exists as a solid d. a sample of sarin at 100C exists as a gas e. a sample of sarin at 170C exists as a liquid
a sample of sarin at -100C exists as a solid solid [-56MP] liquid [158BP] gas
which statement concerning solutions is true? a. a solution is a heterogeneous mixture of 2 or more pure substances b. a solution forms when the solvent and the solute react to form a new substance c. a solution has it components distributed unevenly d. a solution is likely to form if the solute and the solvent have different polarities e. a solution is composed of a solvent and one or more solutes
a solution is composed of a solvent and one or more solutes
which of the following properly describes a colligative property of a solution? a. a solution property that depends on the identity of the solute particles b. a solution property that depends on the polarity of the solute particles c. a solution property that depends on the number of solute particles d. a solution property that depends on the pressure of the solute particles e. a solution property that depends on the number, identity & pressure of the solute particles
a solution property that depends on the number of solute particles
which of the following objects has the largest kinetic energy? [KE=1/2mv^2] a. a truck moving at 10 miles per hour b. a tennis ball moving at 10 miles per hour c. a car moving at 50 miles per hour d. a truck moving a 50 miles per hour
a truck moving a 50 miles per hour
which one of the following actions can alter the activation energy of a reaction?
adding a catalyst
what is the general name given to the elements of Group 1A (or group 1)? a. halogens b. alkali metals c. alkaline earth metals d. noble gases e. metalloids
alkali metals
why is it important to study chemistry? a. to help inform us about our world b. to be better able to make informed decisions c. to help us learn a technique for identifying and solving problems d. all the above
all the above
solutions can be which of the following? a. solid dissolved in liquid b. solid dissolved in solid c. gas dissolved in solid d. gas dissolved in liquid e. all the above
all the above G->s g->L
Rutherford's experiment, in which alpha particles were aimed at a thin piece of gold foil, led to what understanding? a. neutrons existed b. electrons existed & have a negative charge c. the number of electrons can be determined by the mass number and atomic number d. electrons can be promoted to higher energy levels by absorbing energy e. an atom is mostly empty space (w/in atom)
an atom is mostly empty space (w/in atom)
when a neutral atom gains one or more electrons, what type of particle is formed? a. anion (-) b. isotope c. positron d. cation (+)
anion (gains = -)
which statement correctly describes the octet rule? a. atoms tend to attain eight protons in their nucleus to have the stability of the nearest noble gas b. atoms have a tendency to form eight bonds with other atoms to attain the stability of a noble gas c. atoms will lose, gain or share eight electrons to become a noble gas d. atoms are most stable with eight electrons in their outermost shell - the same electron configuration as a noble gas e. atoms are most stable when the number of protons they contain is identical to the noble gas closest to them in the periodic table
atoms are most stable with eight electrons in their outermost shell - the same electron configuration as a noble gas
Consider the two beakers labeled A and B. Beaker A contains 1 mole of iron atoms, and Beaker B contains 1 mole of lead atoms. Which statement concerning these samples is known with certainty? a. beakers A & B contain an equal number of atoms b. beakers A & B contain equal masses of atoms c. beakers A & B contain an equal volume of atoms d. beakers A & B contain samples with the same density e. none of the above is known with certainty
beakers A & B contain an equal number of atoms (1 mole = 1 mole)
in the hypothetical molecule SeCl2, the central atom Se has two lone pairs (..) of electrons in additions to the two bond pairs (II) in the Se-Cl bonds, what is the shape of this molecule? (draw it) a. bent bond angle is about 109.5 ( x4) b. bent; bond angle is about 120 (x3)\ c. linear; bond angle is 180 d. trigonal planar; bond angle is 120 (x3) e. trigonal pyramidal; bond angle is 109.5 (fake 4)
bent bond angle is about 109.5 ( x4) : Se: I I .. .. :Cl Cl: .. ..
where on the periodic table are elements with the lowest electronegativity values found? (highest = up&--->) a. upper right corner (highest) b. bottom right corner c. upper left corner d. bottom left corner (lowest) e. middle
bottom left corner (lowest)
What type of liquid displays the Tyndall effect?
colloidal suspension
what process is responsible for the formation of dew on the grass early in the morning? a. sublimation b. evaporation c. condensation d. freezing e. deposition
condensation
what type of reaction is the reaction shown below (the classic experiment which led to the law of conservation of mass)? 2HgO(s) --> 2Hh(l) + O2(g) a. decomposition (1-->2) b. combination (2-->1) c. single replacement (divorce) d. double replacement (swingers) e. combustion
decomposition (1-->2)
how can pure water be made to boil at a temperature below 100C? a. increase the volume of water b. decrease the volume of water c. increase the pressure about 1 atm d. decrease the pressure below 1 atm e. increase the heat
decrease the pressure below 1 atm (mnt top=decrease pressure)
what are the three primary subatomic particles found in an atom? a. neutron, positron & electron b. electron, neutron & proton c. electron, proton & nucleon d. proton, electron & neutrino
electron, neutron & proton
which term describes the measure of the randomness or disorder of a chemical system? a. energy b. calorimetry c. entropy (ΔS) d. enthalpy (ΔH) e. free energy (ΔG)
entropy (ΔS)
what state(s) of matter is most compressible? a. solid b. liquid c. gas
gas
what form of water has no definite shape and no definite volume? a. solid ice b. liquid water c. gaseous steam
gaseous steam
which statement concerning the 3 states of matter is true? a. particles of a gas are well separated, have a regular arrangement & move fast b. particles of a solid move fast & are held together by strong attractive forces c. particles of a liquid have a rigid, ordered arrangement d. gases have low density & high compressibility e. phase changes between the 3 states of matter are chemical changes
gases have low density & high compressibility
muddy water is which of the following? a. element b. compound c. homogeneous mixture d. heterogeneous mixture
heterogeneous mixture
what term is used to describe a compound that contains water molecules incorporated into its structure? a. aqueous (solutions) b. water-laden c. condensation d. hydrate e. condensate
hydrate
which best explains why an AL^3+ ion is smaller than an Al atom? a. in forming the AL^3+ ion, the al atom loses the electrons in its outermost energy level, causing a decrease in the atomic radius b. in forming AL^3+ ion, the Al atom gains three protons and the resulting net positive charge keeps the electrons more strongly attracted to the nucleus, reducing the radius c. the AL^3+ ion contains more electrons that the AL atom, which results in a greater attraction for the nucleus and a smaller atomic radius d. in forming the AL^3+ ion, the Al atom adds electrons into a higher energy level, causing a decrease in the atomic radius e. there are more protons in an AL^3+ ion than there are in an Al atom
in forming the AL^3+ ion, the al atom loses the electrons in its outermost energy level, causing a decrease in the atomic radius
which of the following is a chemical property of gold (Au)? a. characteristic color b. electrical conductivity c. lack of reactivity d. none, they are all physical properties
lack of reactivity
the drug lithium is often prescribed to treat mental illness. it is not the element lithium, but the ionic compound Li2CO3, that is actually administrated. what is the name of this compound? a. dilithium carbon trioxide b. lithium carbide c. lithium carboxide d. lithium carbonate e. lithium tricarbonate
lithium carbonate (ionic compound = don't count! gp 1A metal)
the ion K+ if formed by which process? a. loss of an electron by K b. gain of proton by K c. loss of a proton by K d. gain of a proton by K e. none of the above
loss of an electron by K
the solubility of gases in liquids is highest at? a. low temp & low pressure b. low temp & high pressure c. high temp & low pressure d. high temp & high pressure e. high pressure; temp is immaterial
low temp & high pressure (soda tastes good)
what term describes the temperature at which a solid is converted into a liquid? a. critical point b. flash point c. sublimation point d. melting point (freezing point) e. boiling point
melting point (freezing point)
which combination of atoms is most likely to form an ionic compound if they are allowed to react with each other? a. metal & metal b. metal & nonmetal c. nonmetal & nonmetal d. metalloid & metalloid e. all combinations are likely to form an ionic compound
metal and nonmetal
what is the general term for when a chemical species LOSES electrons? a. oxidation b. reduction c. deoxidation d. lewis base e. decomposition
oxidation (lose e = +) Loses e(+) reducing agent causes reduction is oxidized
when water is boiled, is that a physical or chemical change? a. physical b. chemical
physical
what is happening in the half reaction shown below? F2 (0) +2e- --> 2F- (-2) a. oxidation b. reduction c. decomposition d. combustion e. both a & b are correct
reduction F gains electron (-2) = reduction!!
ringer solution is used in the treatment of burns and wounds. it is prepared by dissolving 8.6g of NaCl, 0.30g of KCl & 0.33g of CaCl2 in water, and diluting to a volume of 1.0L. which of the following is an accurate description of ringers solutions? a. NaCl is the solvent in this solution b. NaCl, KCl and CaCl2 are all solvents c. ringers solution is a solid solutions (like gold) d. ringers solution is a heterogeneous mixture e. ringers solutions is an aqueous solutions (water)
ringers solutions is an aqueous solutions (water)
what type of membrane allows solvent molecules to pass through, but does not allow solute molecules to pass through? a. transport b. colloidal c. transparent d. semipermeable e. latex
semipermeable
a covalent bond involves which of the following? a. sharing of electrons b/t 2 atoms b. transfer of electrons b/t 2 atoms c. donation of protons from one atom to another d. electrostatic attraction b/t opposite charges e. sharing of protons b/t 2 atoms
sharing of electrons b/t 2 atoms
will the compound in question 12 (2.43g/mL) float or sink in water? (assuming it does not mix with the water) *water is 1.00g/mL* a. float b. sink
sink
what is the name of the ionic compound (don't count) with the formula Na3PO4? (look on table) a. silver phosphite b. sodium phosphorus oxide c. sodium tetraphosphate d. trisodium phosphate e. sodium phosphate
sodium phosphate
in general, which state of matter has the lowest entropy? (ΔS) a. solid b. liquid c. gas d. plasma e. liquid crystal
solida
which of the following represent STP (standard temperature and pressure) conditions? (0C=273K=1ATM=760mmHg=76.0torr)
t=273K & p=1 atm
the ionic compound iron (II) sulfate (transition metal) is used in iron-containing supplements. what does the (II) in the name of this compound indicate? a. there are two iron ions in this compound? b. the charge on the iron ion is +2 c. the charge on the sulfate ion is-2 d. iron has two valence electrons e. there are two sulfate ions in this compound
the charge on the iron ion is +2
which of the following is true about the energy diagram shown? (exo diagram)
the energy of the products is lower than the energy of the reactants
hydrogen can form two different ions: a hydrogen ion (H+) & a hydride ion (H-). which statement concerning these ions if false? a. the H+ ion is a cation formed by the loss of one electron; this ion has 0 valence electrons b. the H- ion is an anion formed by the gain of one electron; this ion has 2 valence electrons c. the hydrogen ion and the hydride ion are isotope d. the hydrogen ion and the hydride ion have the same number of protons e. the hydrogen ion and the hydride ion have different sizes
the hydrogen ion and the hydride ion are isotope (neutrons)
the solubility of a solute (dissolves-less) is best described as which of the following? a. the ability of the solute to dissolve in water b. the ability of the solute to dissociate into ions when dissolved in water c. the mass of solute to dissolve in 1L of water at a specific temperature d. the maximum amount of solute that can be dissolved in a specified amount of solvent (does dissolving-more) at a specific temp e. the number of moles of solute that can dissolve in either 1L of solution (M) or 1 kg of solvent (m) at a specific temp
the maximum amount of solute that can be dissolved in a specified amount of solvent (does dissolving-more) at a specific temp
what statement about the ammonia molecule, NH3 is true? (hint: you will likely need to draw the lewis structure of the molecule) a. the molecule contains tree nonpolar bonds b. the molecule itself is polar c. the molecule has a trigonal plana shape d. the nitrogen atom has two lone (nonbonding) pairs of electrons e. the pull of the electrons in the N-H bonds is toward the hydrogen atoms
the molecule itself is polar (asymmetrical) .. H--N--H I H
the identity of an atom is determined by which of the following? a. the number of electrons it contains b. its mass number c. the number of isotopes it has d. the number of protons it contains e. the number of protons and neutrons it contains
the number of protons it contains
what are valence electrons? a. the electrons located in the nucleus of an atom b. the interior electrons, located closet to the nucleus c. the outermost electrons in an atom d. the electrons with the lowest energy in an atom e. the total number of electrons in an atom
the outermost electrons in an atom
which statement correctly describes what happens to a sample of gas when it experiences an increase in temperature? a. the volume of the gas decreases, as long as the pressure remains constant b. the pressure of the gas increases, if the volume remains constant c. the speed of the gas particles decreases d. the number of gas particles increases e. the density of the gas increases
the pressure of the gas increases, if the volume remains constant P1V1/T1
an aerosol spray paint can with a volume of 350 mL registers a pressure of 4.5 atm at room temperature. what can be said about the pressure inside the can if it stored outside during the winter months? a. the pressure of the gas will be greater than 4.5 atm b. the pressure of the gas will be less than 4.5 atm c. the pressure of the gas will remain at 4.5 atm d. the pressure of the gas will be 1575 atm e. it is impossible to say anything about the pressure without additional information
the pressure of the gas will be less than 4.5 atm (pressure cooker, V=set, pressure cooker)
When a cold-pack is activated, a chemical reaction occurs and the temperature of the pack contents drops sharply. Which of the following is a correct description of the reaction occurring in the pack? a. the reaction is exothermic; ΔH>0 b. the reaction is exothermic; ΔH<0 c. the reaction is endothermic; ΔH>0 d. the reaction is endothermic; ΔH<0 e. none of these choices are correct
the reaction is endothermic; ΔH>0 (absorbs heat = endo)
a student combines 4.0 g of KNO3 with 5.0 mL of water at room temperature, stirs it well and observes that most, but not all, of the KNO3 has dissolved. which statement concerning this solution is true? a. the solution is supersaturated (solution with more dissolved solute than the solvent would normally dissolve in its current conditions) b. the solution is unsaturated (solute concentration is lower) c. the solution is saturated (maximum concentration of a solute dissolved in the solvent) d. KNO3 is not soluble in water e. in order to get the additional KNO3 to dissolve, the student can add more solute
the solution is saturated
consider the decompostition of calcium carbonate shown below. which of the following statements correctly describes this reaction (rx) as it occurs in a test tube? CaCO3(s) + 42.5 kcal --> CaO(s) + CO2(g)
the test tube would feel cold, since the rx absorbs heat from the surroundings (absorbs energy =cold=endo/kcal as reactant)
an explanation of a fact that has been successfully tested is known as? a. observation b. hypothesis c. theory d. law
theory
emergency treatment of cardiac arrest victims sometimes involves injection of a calcium chloride (CaCl2) solution directly into the heart muscle. which statement about the compound CaCl2 is TRUE? a. this compound is covalent (2 nonmetals) b. the cation in this compound is C c. the anion in this compound is Cl2- d. there are two separate chloride ions in this compound e. the compound is charged
there are two separate chloride ions in this compound (Ca=metal+ & Cl=halogen-)
what is always true for a neutral atom? a. there is an equal number of protons & neutrons b. there is an equal number of protons & electrons c. there is an equal number of protons, neutrons, & electrons d. the number of protons and neutrons is an even number e. the number of protons, neutrons and electrons is an even number
there is an equal number of protons & electrons
which of the following correctly describes what happens when red blood cells are placed in a hypertonic (salty) solution? a. there will be a net movement of water into the rbc's and the cells swell & burst - hemolysis (hypotonic) b. there will be a net movement of water out of the rbc's and the cells will shrink and collapse- crenation (hypertonic)
there will be a net movement of water out of the rbc's and the cells will shrink and collapse- crenation
what do the dots in a Lewis symbol represent? a. protons b. valence electrons c. innermost (core) electrons d. the nucleus e. mass number
valence electrons
Vit D is essential for the normal development of teeth and bones. a tablet of Vit D is tested for solubility in water and benzene. the results are shown in the table. what is the most appropriate interpretation of the solubility results? Water(H2O, polar) benzene(C6H6, nonpolar) Vit D is insoluble Vit D is soluble a. vit d is likely a nonpolar substance b. vit d is likely a polar substance c. vit d is likely a bipolar substance d. vit d is likely an iconic compound e. it is impossible to say anything about the polarity/structure of vit D
vit d is likely a nonpolar substance
