Praxis Chemistry

What is the oxidation number of Cl in HClO3?

+5 Option (A) is correct. The oxidation number of ClC l is +5plus 5. In HClO3 the oxidation number of O is -2minus 2 and the oxidation number of H is +1plus one. The total oxidation number for the entire formula must be zero. So 3(-2) + 1 + x = 03 times negative 2, plus one, plus x, equals zero, where x = 5x equals 5.

Which of the following is always true for a spontaneous process? (U is internal energy, H is enthalpy, S is entropy, and G is Gibbs energy.)

. ΔS universe>0

What is the mole fraction of glucose in a 2.5 m2 point 5 molal aqueous solution of glucose? (m is molal.)

0.043 Option (C) is correct. A 2.5 m aqueous glucose solution has 2.5 mol glucose in 1,000 g of water (55.6 mol water)55 point 6 moles. The mole fraction of glucose is Xglucose=(2.5/55.6+2.5)=0.043.

H2(g) + Br2(g)⇌2 HBr(g) An equation is shown as follows: H2 gas, and Br2 gas, is in equilibrium with 2HBr gas A 0.34 mol zero point three four mole sample of H2(g)H 2 gas is added to a sealed 1.0 Lone point zero liter container with 0.22 mol zero point two two mole of Br2(g) gas in it. The mixture is allowed to come to equilibrium at 700 K, as represented by the equation above. When equilibrium is established and analyzed, it is found that 0.14 mol zero point one four mole of H2(g) gas is present. How much HBr(g)gas is present at equilibrium?

0.20 mol H2 * 2 HBr/1H2 = 0.40 mol HBr

What is the approximate sodium ion concentration in a solution that results from the addition of 50.0 mL of 0.10 M NaCl to 100.0 mL of 0.20 M Na2SO4?

0.30M 0.0450 mol/150L = 0.30M

Which of the following solutions at 298 K would exhibit a pH that is greater than 7 ?

0.5 M K3PO4

For PbCl2 at 298 K, = 1.6 × 10^-5 Ksp. The molar solubility of PbCl2 is

1.6*10^-2

Of the following, which has the largest amount of kinetic energy?

100 g of water vapor at 101°C

A saturated solution of KNO3 in 100 g of water at 70°C is cooled to 10°C. Needle-shaped crystals form as the solution is cooled to 10°C. Based on the solubility curve above, what mass of KNO3 should precipitate from the solution?

115 g

__C4H10 + __O2 --> __CO2 + __H2O When the equation above is balanced using the lowest whole-number coefficients possible, the coefficient for O2O 2 is

13 2C4H10 + 13 O2 -> 8CO2 +10H2O

A 0.20 M solution of a weak monoprotic acid is 3.0 percent ionized. What is the approximate pH of the solution?

2.0-3.0 Option (A) is correct. For the solution, pH = -log[H+]p H equals negative log of the concentration of H plus. In a 3.0three point zero percent ionized 0.20 Mzero point two zero molar acid solution, [H+] = (0.03) x (0.20 mol/L) = 0.0060 Mthe concentration of H plus equals zero point zero three times, zero point 2 zero mole per liter, equals, zero point zero zero six zero molar. The pH = -log(0.0060) = 2.22p H equals negative log of zero point zero zero six zero, equals 2 point two two, which is in the range of 2.02 point zero to 3.03 point zero.

4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(l) A reaction is shown as follows: 4 N H 3 gas reacts with 5 O 2 gas to produce 4 N O gas and 6 H 2 O liquid If 34.0 g34 point zero grams of NH3N H 3 reacts with 32.0 g32 point zero grams of O2 according to the reaction shown above, what is the maximum mass of H2O that will form?

21.6 g (1 mol O2) × (6 mol H2O)/(5 mol O2) × (18 g/mol H2O) = 21.6 g H2O)

CaC2(s) + 2 H2O(l) →Ca(OH)2(aq) + C2H2(g) According to the reaction represented above, what volume of C2H2 gas is produced at 0.00°C and 1.00 atm when 1.00 mol CaC2(s) solid reacts completely with excess water?

22.4L

A particular isotope of an element is radioactive. A pure 200.0 g sample of the radioisotope is put into a sealed lead container. Exactly three days later an analysis reveals that the sample contains only 25 g of the radioisotope. Which of the following is the half-life of the radioisotope?

24 hours

Each nitrogen atom in Ca(NO3) 2 • 6 H2OC a, parenthesis N O 3 close parenthesis, 2, dot 6 H 2 O forms a covalent bond with

3 atoms

Which of the following correctly expresses the number 0.003930 in scientific notation?

3.930 X 10^-3

A portion of a buret containing a liquid is shown above. The correct volume reading for the liquid in the buret should have a total of how many significant figures?

4

__ H2SO3 + __ Mn + __ H+ →__ S + __ Mn2+ + __ H2O A reaction is shown as follows: H 2 S O 3 and M n and H positive one ion, react to produce, S, and M n positive 2 ion, and H 2 O If the oxidation-reduction reaction represented above is balanced using the smallest whole-number coefficients possible, the coefficient for H+ plus is

4

If a gasoline-powered automobile burns 1,500 kg of gasoline per year, what is the approximate mass of CO2 gas that is released per year for the automobile? (Assume that gasoline is about 80% carbon by mass.)

4,400 kg (0.80×1,500 kg = 1,200 kg)

The number of moles of oxygen atoms in 0.50 mole of Ba(NO3)2 • 2 H2O is

4.0

Mg3N2(s) + 6 H2O(l) → 2 NH3(g) + 3 Mg(OH)2(s) According to the reaction represented above, if 2.0 mol Mg3N2(s) reacts with excess water, what is the maximum amount of NH3(g) that can form?

4.0 mol 2 mol Mg3N2 * (2 mol of NH3/1 mol of Mg3N2) = 4 mol of NH3

In a 0.050 M solution of an unknown acid, HA, the percentage dissociation of HA s 1.0%. The KaK a, of this acid is

5.1*10^-6 Ka = [H+][A-]/[HA], the concentration of H plus, times the concentration of A negative one ion, divided by the concentration of H A. When the acid dissociates 1.0%one point zero percent, [H+] = [A-] = (0.01)(0.050 M) = 0.00050 Mthe concentration of H plus equals, the concentration of A negative one ion, equals zero point zero one, times, zero point zero 5 zero molar, equals zero point zero zero zero five zero molar. [HA] = (0.050 - 0.00050) = 0.0495 M.the concentration of H A equals, zero point zero five zero minus zero point zero zero zero five zero, equals zero point zero four nine five molar Hence, Ka = (0.00050)(0.00050)/(0.04950) = 5.1 × 10-6

Sample Initial Temperature Mass 1 70.0°C 100.0 g 2 40.0°C 200.0 g The two samples of water described above are mixed in a thermally insulated container. The temperature of the mixture at thermal equilibrium is

50*C

In the diagram above, gas A is trapped in a sealed container with an open-ended manometer attached. The ambient room pressure that day is 765 mm Hg765 millimeters H g. What is the pressure of gas A in this experiment?

752 mmhg Option (B) is correct. The manometer is open-ended. This means that the surrounding pressure must be accounted for in the observation. Since the level of mercury on the gas A side is higher than on the side open to the room, the pressure of gas A must be lower than that of the room. Subtracting the values at each side of the manometer gives the difference in the column heights. This difference is about 13 mm Hg. The final calculation is 765 mm Hg - 13 mm Hg = 752 mm Hg765 millimeters H g minus 13 millimeters H g, which equals 752 millimeters H g.

If the specific heat of water is approximately 4.2 J g-1 °C-1 , how much heat is absorbed by 10.0 g of water as the temperature is increased from 30.0°C to 50.0°C?

840J Q = Cmt = (4.2J)*(10.0) * (50-30) = 840

A student needs to make 10.0 L liters of 0.050 M C6H12O6(aq). What mass of C6H12O6 is needed?

90 g

Which of the following compounds is an ether?

A. CH3OCH2CH3 B. CH3CH2CH3 C. CH3CH2OH D. CH3CH2COOH Option (A) is correct. Option A is an ether, option B is an alkane, option C is an alcohol, and option D is a carboxylic acid.

Which of the following correctly pairs the quantity being measured with an appropriate unit? A. Enthalpy change during the combustion of gasoline . . joule B. Voltage of a car battery . . ohms C. Surface area of a sphere . . cm3centimeters cubed D. Number of atoms present in a sample of sulfur . . µg

A. Enthalpy change during the combustion of gasoline . . joule

Which of the following is a renewable energy source? A. Wind B. Coal C. Uranium D. Natural gas

A. Wind

The concentration of a 10.0 mL sample of sulfuric acid, H2SO4(aq)H 2 S O 4 aqueous, was determined by titrating it with 0.10 M KOH(aq)zero point one zero molar, K O H. If 16.0 mL of the KOHK O H solution is required to reach the equivalence point, what is the concentration of the 10.0 mL sample of sulfuric acid?

A.0.080 M

Petroleum, or crude oil, consists of a mixture of compounds that can be separated into simpler fractions by the process of distillation. Which of the following properties of the different compounds is the basis for separating the fractions of crude oil by distillation?

A.Boiling point

When solid PbI2 is added to a saturated solution of PbI2, which of the following correctly describes what happens to the concentration of lead ions, [Pb2+] and the concentration of iodide ions, [I-]open bracket, I negative one ions, close bracket?

A.Both [Pb2+]the concentration of P b positive 2 ions and [I-]the concentration of I negative one ions remain the same.

When a sample of solid lead(II) iodide is placed in water, only some of the solid will dissolve, and the process is endothermic. Which of the following will increase the concentration of dissolved lead(II) iodide in a saturated solution?

A.Heat the solution.

The process of collecting raw data during an experiment is best described as which of the following?

A.Making observations

The symbol above is related to which of the following contexts?

A.Recycling of plastic

Which of the following statements concerning temperature scales is correct?

A.The Fahrenheit and Celsius temperature scales coincide at -40° degrees.

Which THREE of the following are included in the Lewis dot model for molecular structure of NH3 ?

A.The valence electrons B.The nonbonding electrons D.The bonds

Which THREE of the following are safe laboratory practices?

A.Using a fume hood when working with chemicals that produce poisonous vapors B.Performing an experiment using the smallest amount of chemical possible D.Neutralizing hydrochloric acid before disposing of it in a public sewer system

The process illustrated above is used when separating

A.a precipitate from an aqueous solution

Which of the following compounds is only slightly soluble in water? CsCl LiCl AgCl NH4Cl

AgCl Option (C) is correct. Based on solubility rules, most chloride compounds are very soluble in water, but AgCl is only slightly soluble.

Of the following 0.5 M aqueous solutions, which has the lowest freezing point?

Al(NO3)3 solution will have the largest concentration of particles in solution and hence the lowest freezing point.

Proteins are composed of which of the following?

Amino acids

The compound CH3NH2 is classified as which of the following?

An amine

Of the following, which THREE describe a saturated solution at 25°C? A.0.1 M NaCl(aq)zero point one molar, N a C l aqueous B.Solid I2I 2 in equilibrium with a solution of I2I 2 dissolved in CCl4 C.A bottle of soda sealed under a pressure of 1.2 atmone point 2 atmosphere of CO2(g) D.A solution prepared by mixing 1 M AgNO3(aq) with 1 M NaCl(aq)

B.Solid I2I 2 in equilibrium with a solution of I2I 2 dissolved in CCl4 C.A bottle of soda sealed under a pressure of 1.2 atmone point 2 atmosphere of CO2(g) D.A solution prepared by mixing 1 M AgNO3(aq) with 1 M NaCl(aq)

A sample of acid rain taken at one location (sample 1) has a pHp H of 4.0 and a second sample taken at another location (sample 2) has a pHp H of 5.0. Which of the following is true about sample 1 and sample 2?

B.The concentration of H+H plus ions in sample 1 is ten times higher than in sample 2.

When preparing diluted sulfuric acid, H2SO4(aq), the concentrated acid should be added to the water, not the other way around. Which of the following reasons accounts for this procedure?

B.The dilution process is highly exothermic, so the solution may splatter if water is added to the concentrated acid.

Which of the following will generally result in a faster rate of dissolving for a solid in a solvent in a beaker?

B.Using a powdered form of the solid rather than large crystals Option (B) is correct. Using a powdered form of the solid will increase the surface area of solid exposed to the solvent and will result in a faster dissolving rate.

Of the following processes, which involves a physical change only?

B.Water boiling in a teakettle

Dalton proposed that all matter is composed of indivisible particles called atoms. This proposal is

B.a theory

Which of the following processes results in an increase in the atomic number of the product nucleus?

Beta emission

Which of the following scientists developed the mathematical relationship between pressure and volume of a gas sample at constant temperature?

Boyle

Which of the following elements is a liquid at 25ºC and 1 atmone atmosphere?

Br2

When 30.0 g of sodium and 8.0 g8 point zero grams of oxygen react in a closed vessel to produce 31.0 g31 point zero grams of sodium oxide, which of the following, if any, will remain unreacted?

C. 7.0 g Na

2 KClO3(s) →2 KCl(s) + 3 O2(g)

C.Decomposition

Which of the following is true about the electromagnetic radiation emitted from atoms with a wavelength of 397 nm compared to emitted electromagnetic radiation with a wavelength of 656 nm?

C.The radiation with wavelength of 397 nm has higher energy than the radiation with a wavelength of 656 nm. (E=h×cλ) Option (C) is correct. The energy of electromagnetic radiation is inversely proportional to its wavelength. Since 397 nm is a shorter wavelength than 656 nm, it is has a higher energy than the radiation with a wavelength of 656 nm. (E=h×cλ)

Which of the following is true about hydrogen nuclear fusion as a potential energy source?

C.The technology for large-scale energy production is currently not available.

Which of the following is the geometry of the ammonia molecule, NH3?

C.Trigonal pyramidal

Rate = k[NO]2[Br2] Based on the rate expression given above, if the concentration of NO is doubled, all other factors being constant, the rate of the reaction will

C.increase by a factor of 4

A compound contains 53.3% C, 15.6% H, and 31.1% N. Which of the following could be the empirical formula of the compound?

C2H7N

A 1:1 mixture of which of the following pairs of 0.20 M aqueous solutions will form a buffer solution?

CH3COOH and CH3COONa A buffer can formed by a 1:1one to one mixture of a weak acid (CH3COOH) and a salt (CH3COONa) a that includes the conjugate base of the weak acid (CH3COO-) negative one ion.

Which of the following gaseous substances dissolves in water to produce a solution containing ions?

CO2

Which of the following is a reactant in the net reaction for photosynthesis?

CO2

Of the following elements, which is most similar to MgM g in chemical reactivity?

Ca

Which of the following is a Brønsted-Lowry acid-base neutralization reaction?

Ca(OH)2(s) + 2 HCl(aq) → CaCl2(aq) + 2 H2O(l) Option (C) is correct. Option C is a Brønsted-Lowry acid-base neutralization reaction in which HCl gives up H+ plus ions and OH-minus accepts the H+H plus ions and forms H2O.

Which of the following pairs of substances are isotopes?

Carbon-13, carbon-14

The electronic emission spectrum of atomic hydrogen is due to which of the following?

D.Excited electrons making a transition to a lower energy state

A student measured the mass of an object five times and recorded the data in the table above. Having completed the required measurements, the student is informed that the accepted mass of the object is 10.9 grams. Which of the following best describes the nature of the student's data? Trials 1 2 3 4 5 Mass 11.50 11.20 10.90 10.90 10.30

D.The data had poor precision but good accuracy.

If one mole of an ideal gas with a pressure of 1.0 atm expands from 15 L15 liters to 30 L30 liters at constant temperature, which of the following is true about the gas?

D.The pressure will decrease to 0.5 atm. Option (D) is correct. Based on the ideal gas law, when an ideal gas expands from 15 L15 liters to 30 L30 liters at 1.0 atm and at constant temperature, the pressure will decrease to 0.5 atm (half the initial pressure). P2 = P1 × (V1/V2) = 1 atm × (15 L/30 L) = 0.5 atm.

Which of the following is a conclusion rather than an observation about the heating of a cube of an unknown solid?

D.The unknown solid is H2O.

2 SO2(g) + O2(g) ⇌2 SO3(g) ΔH°<0 A reaction is shown as follows: 2SO2 gas and O2 gas, is in equilibrium with 2SO3 gas, where the change in standard enthalpy, delta H zero, is less than zero Which of the following will cause an increase in the value of the equilibrium constant, K, for the reaction represented by the equation above?

Decreasing the temperature of the reaction vessel at constant pressure Of the four options, only a change in temperature changes K for an equilibrium reaction. If the temperature is decreased, for an exothermic reaction at constant pressure, K is increased. Thus the equilibrium favors the formation of additional product.

Supporting evidence for the particle-like nature of light was provided by which of the following phenomena?

Einstein proposed that light can also be described as having particle-like properties. Packets of energy, called photons, strike the surface of a metal, causing electrons to be ejected, but only if the photons have a critical minimum energy (minimum light frequency). If the energy of the photons is greater than the minimum required, the number of electrons ejected is proportional to the number of photons (or intensity of the light) striking the surface.

Which THREE of the following properties of a substance change during a phase change?

Entropy, Enthalpy, Internal Energy NOT Temperature

The formula for sulfurous acid is

H2SO3

Which of the following compounds can exhibit hydrogen bonding between its molecules?

HF

Which of the following is the conjugate base of H2SO4 ?

HSO4- Option (C) is correct. The conjugate base of an acid HAH A is A-A, negative one ion in this example. H2SO4 + H2O ⇌ HSO4- + H3O+H 2 S O 4 and H 2 O, are in equilibrium with H S O 4 negative one ion and H 3 O positive one ion. Therefore the conjugate base of H2SO4H 2 S O 4 is HSO4-H S O 4 negative one ion.

Which of the following equations represents an oxidation‑reduction reaction?

I2 (s) + 2HCl (aq) -> 2 HI (aq) +Cl2 (g)

Sodium metal reacts vigorously with cold water to produce heat, a metal hydroxide, and a gas. Based on position on the periodic table, which of the following would have a similar reaction with water?

K potassium

Which of the following chemical substances contains only ionic bonds?

K2O Option (A) is correct. Potassium is a metal and oxygen is a nonmetal. The differences in electronegativities predict that they will form a compound with an ionic bond. NaNO3 is also an ionic compound, but the nitrate ion has covalent bonds between nitrogen and oxygen. CO2 and O2 are both molecules with covalent bonds only.

2 ICl(g) ⇌ I2(g) + Cl2(g) For the reaction represented above, [Cl2] = 0.045 M, [I2] = 0.045, and [ICl] = 0.13 M at equilibrium. Which of the following expresses the equilibrium constant in terms of concentration, Kc?

Kc=[I2][Cl2]/[ICl]2. Hence, Kc = (0.045)2/(0.13)2.

Which of the following is considered the primary intermolecular attraction between molecules of butane, C4H10, in the liquid state?

London-dispersion forces Since difference in the electronegativities between C and H is small, the C-H essentially nonpolar. Hence, there is not a permanent dipole in the butane molecule. The primary intermolecular attraction results from instantaneous and temporary dipoles, and these forces are called London dispersion forces.CH3COOHC H 3 C O O H and CH3COONa

A metal M and oxygen form a compound with the chemical formula MO. What is the most likely chemical formula of a compound formed from M and phosphorus?

M3P2

Of the following atoms, which has the highest electronegativity?

N

Students are to prepare a 1.0 Mone point zero molar aqueous solution of NaOHN a O H for use in an experiment. They are instructed to determine the mass of NaOHN a O H needed and to weigh out the sample of NaOHN a O H. The teacher warns the students to weigh the sample as quickly as possible while still being precise and safe. Which of the following explains why the students need to work quickly?

NaOH is deliquescent (absorbs water from the air) and will gain mass if exposed to the room air for prolonged periods of time.

Which of the following ions has a total of nine electrons?

Ne+

What is the typical nuclear condition of an atom that produces gamma radiation?

Nucleus in an excited state.

Based on the molar masses given above, which element accounts for the largest percent of the molar mass of H3PO4? H 1.0g P 31.0 g O 16.0 g

O Option (C) is correct. Oxygen accounts for the largest percent of the molar mass of the compound. The percent composition of oxygen in the compound is found as follows: %O=4(16)[3(1) + 31 + 4(16)]×100%=64/98=65%.

The pH of a 0.002 M HCl solution is closest to

Option (A) is correct. The pH is found as follows: pH = -log [H+] = log[2 × 10-3] = 2.7p H equals negative log of the concentration of H plus, equals log of 2 times 10 to the negative 3, equals 2 point seven, assuming 100 percent dissociation.

NaNO3(aq) + Pb(s) → NaNO2(aq) + PbO(s) A reaction is shown as follows: NaNO3 aqueous reacts with Pb solid to produce NaNO2 aqueous and P b O solid For the oxidation-reduction reaction represented above, which of the following is the reduction half reaction that occurs?

Option (A) is correct. The reduction half reaction is N5+ + 2 e-→ N3-2 electrons produces N positive 3 ion. In NaNO3N a N O 3 the oxidation number for N is +5positive 5, and in the product NaNO2 the oxidation number for N has been reduced to +3.

What is the concentration of OH- ions in a solution with pH = 6.0?

Option (B) is correct. If pH = 6.0, then pOH = 8 since pH + pOH = 14p [OH-] = 1 × 10-8 since pH + pOH = -log[OH-]= 1*10^8 equals -log[OH-].

Which of the following is a strong electrolyte? A. CH3COOH(aq) B.MgCl2(aq) C.NH4OH(aq) D.C6H12O6(aq)

Option (B) is correct. MgCl2M g C l 2 dissociates almost 100% and is a strong electrolyte. Options A and C only partially dissociate and are weak electrolytes. Option D does not dissociate; it is not an electrolyte.

Element X is composed of four stable isotopes. The masses and respective relative abundances of its isotopes are as shown in the table above. The approximate atomic mass of element X in amua m u is closest to

Option (B) is correct. The atomic mass is determined by calculating the weighted average of all of the commonly occurring isotopes of an element, which is the sum of the isotope mass multiplied by its relative abundance. The atomic mass = (30 amu)(0.15) + (32 amu)(0.70) + (34 amu)(0.1) + (35 amu)(0.05) = 32.05 amu. In this problem, the atomic mass can be estimated because of the large abundance of isotope X-32 and distribution of lower and higher mass isotopes.

Which of the following is a homogeneous mixture? a. seawater b. liquid mercury c. HCl (aq) d. granite

Option (C) is correct. HCl(aq) is a homogeneous mixture that appears as one phase and is composed of H+(aq), Cl-(aq), and water.

The warming curve above represents the data collected during an experiment using water. The initial temperature of the water was -25°C. Energy was added at a constant rate of 500 joules per minute until the temperature of the water reached 150ºC. The temperature was recorded every 0.5 minutes. The mass of water was constant throughout the experiment. How much heat was added to increase the temperature of water from 0°C zero degrees Celsius to 100°C on the part of the curve represented by segment III?

Option (C) is correct. It took 10 minutes to heat the water from 0°C to 100°C. The amount of heat added was 10 min × 500 joules/min = 5,000 J10 minutes times 500 joules per minute equals 5,000 Joules.

An increase in the temperature of a chemical reaction increases the rate of the reaction primarily because

Option (D) is correct. As described by the Maxwell-Boltzmann distribution, an increase in temperature increases the fraction of molecules with sufficient energy to overcome the activation energy barrier for the reaction.

Of the following common household products, which is most acidic?

Orange juice

Which of the following is the symbol for the element palladium?

Pd

Which of the following atoms has five valence electrons?

Phosphorus (P) in its ground electronic state has five electrons in the highest occupied n shell. The quantum number n is 3, and the electrons are represented by 3s23p3.

A ⇌B + C (fast) A + C→B (slow) The proposed mechanism above is for the reaction 2A →2B Which of the following rate laws is consistent with the proposed reaction mechanism?

Rate = k [A]^2/[B]

Based on its position on the periodic table, which of the following is a transition element?

Rh Rh has atomic number 45 and is a transition element found in the middle section of the periodic table. The electron configuration for RhR h is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d7 5s2 and includes partially filled 4d orbitals.

Which of the following forms an acidic solution in water?

SO3 reacts with water to form the acid H2SO4

Of the following elements, which has the smallest atomic radius?

Sb

A ground-state atom of which of the following elements has an electron with quantum numbers n=4,l=1,and ml=1?

Se

The formula for tin(II) phosphate is

Sn3(PO4)2

A student is planning a classroom experiment for Charles' law which will investigate how the volume of a balloon containing a fixed mass of gas is affected by changes in temperature. Which of the following is the independent variable?

Temperature

Which of the following is true about the bonding in ethane and ethene?

The average carbon-carbon bond length in ethane is longer than in ethene. The average carbon-carbon bond length in ethane (CH3-CH3) single bond between CH3 and CH3, is longer than in ethene (CH2=CH2).double bond between CH2 and CH2 Since the carbon-carbon bond in ethene is a double bond, it is shorter and stronger than the carbon-carbon bond in ethane, which is a single bond.

Ka(HF)=6.76×10^−4 Ksp(AgCl)=1.8×10^−10

The pH increases when a small amount of NaF(s) is dissolved in an aqueous HF solution. AgCl(s) precipitates when 50 mL of 1 M NaCl(aq) is added to 50 mL of 1 M AgNO3(aq). 50 milliliters of one molar AgNO3 (aq) AgCl(s) is a solid precipitates when a small amount of NaCl(s) is dissolved in a saturated aqueous solution of AgCl.

High-pressure steam that is produced from boiling water can be used to move a piston in a steam engine. Of the following energy transformations, which occurs during the process?

Thermal to mechanical

A titration of HCl(aq)H C l aqueous with NaOH(aq)N a O H aqueous was done using phenolphthalein as an indicator. After the addition of a portion of NaOH(aq)N a O H aqueous, the solution turned faint pink after stirring. Which of the following is true at this point in the titration?

[H+] = [OH-]

Which of the following is the electron configuration of an alkaline earth metal?

[Ne]3s2

Ernest Rutherford performed an experiment in which alpha particles collided with gold nuclei. With this experiment, he established that the force between the alpha particle and the nucleus was

a repulsive electric force. The positively charged alpha particle is a helium nucleus (He2+) ion and is repelled when it gets close to the positively charged nucleus.

The reaction represented above can be classified as which THREE of the following reaction types? 2 Mg(s) + O2(g) → 2 MgO(s)

combustion, redox and synthesis Not precipitation because no precipitation is taking place.

A(g) + B(g) →C(g) + D(g) A reaction is shown as follows: A, gas reacts with B gas to produce C gas and D gas Compound C is formed in a single-step reaction, as represented above. The rate law of the reaction is

k[A][B]

In the titration of a certain weak acid (HA), by a strong base, the equivalence point could be at

pH = 8.7

The compound represented above is CH3CH2CH2CH2CH2OH

pentanol

For which of the following rate laws is the rate of the reaction constant and independent of concentration at a fixed temperature?

rate k[A]^0 Option (A) is correct. For the rate law, rate = k[A]Hence, rate = krate equals k and has no dependence on concentration. And k is constant unless temperature is changed. The rate of the reaction is constant and independent of concentration.

The bonding in H2C=CH2double bond between H 2 C and C H 2 involves which of the following hybrid orbital types?

sp2

A(g) + B(g) ⇌ C(g) For the reaction represented above, which of the following is equal to zero at constant temperature and pressure?

ΔG for the reaction