CHEM Question Pack

What is the molar concentration of Na+(aq) in a solution that is prepared by mixing 10 mL of a 0.010 M NaHCO3(aq) solution with 10 mL of a 0.010 M Na2CO3(aq) solution? 0.010 mole/L 0.015 mole/L 0.020 mole/L 0.030 mole/L Ans: 0.015 mole/L

1) Since 1 equivalent of NaHCO3 provides 1 equivalent of Na+, the molar concentration of Na+(aq) in 0.010 M NaHCO3(aq) solution is also 0.010 M = 0.010 mole/L. 2) The molar concentration of Na+(aq) in 0.010 M Na2CO3(aq) solution is 0.020 mol/L since 1 equivalent of Na2CO3 provides 2 equivalents of Na+. 3)When equal volumes of these two solutions are mixed, the resulting molar concentration is equal to their average, (0.010 mol/L + 0.020 mol/L)/2. For next time, pay attention to the equivalent atom given.

Na2CO3 + HCl → CO2 + H2O + NaCl Consider the above unbalanced equation. For this reaction, how many mL of a 2 M solution of Na2CO3 are required to produce 11.2 L of CO2 at STP? 125 mL 250 mL 375 mL 500 mL Ans 250mL

11.2 L CO2 * ( 1mol / 22.4 L CO2) * (1 mol Na2CO3 / 1 mol CO2) * (1L / 2 mol solution) * (1000ml/1L solu) This is a stochiometry question. Solve it yourself before moving on.

Which of the following statements most accurately describes the solubility properties of fatty acid salts? They are soluble in polar media only. They are soluble in nonpolar media only. They can partially dissolve in both polar and nonpolar media. They are completely insoluble in both polar and nonpolar media.

A fatty acid salt contains a long hydrocarbon chain, which is soluble in nonpolar solvents. The salt also contains the charged group -CO2-Na+, which is soluble in polar solvents.

Primary Alcohol

A primary alcohol is an alcohol which has the hydroxyl group connected to a primary carbon atom. It can also be defined as a molecule containing a "-CH₂OH" group

Distillation

A process that separates the substances in a solution based on their boiling points. Include stages of vaporization and condensation. Lowest boiling point first to reach gas phase

According to the information in the passage, the gas that evolves is: sulfur dioxide. sulfur trioxide. Answer: carbon dioxide. carbon monoxide.

According to the passage, the gas is given off when HCl is added to one portion of the slurry. HCl reacts with CO32- to form CO2(g). As a rule of thumb whenever I see Carbonates or Bicarbonate I would go with CO2 forming as a gas specially when water or acidic environment are present.

Aldehyde

An aldehyde /ˈældɪhaɪd/ is a compound containing a functional group with the structure −CHO, consisting of a carbonyl center

Dipolar Ion

An ion charged both positively and negatively (as that of an amino acid in solution) : an amphoteric ion the dipolar ion +H3NCH2COO− of glycine. — called also zwitterion

Hydrogen Bond

Attraction between a slightly positive hydrogen atom and a slightly negative atom. FON

Experiment 1 was repeated with 0.40 g of calcium, and the gas that evolved was collected. The identity of the gas, and its approximate volume at 1.0 atm and 27°C were:(Note: R = 0.0821 L•atm/mol•K) H2, 250 mL. H2, 500 mL. O2, 250 mL. O2, 500 mL.

Calcium undergoes the following reaction with water: Ca(s) + 2H2O(l)→ Ca2+(aq) + 2OH-(aq) + H2(g). The gas produced was H2. If 0.40 g calcium reacted, then the number of moles of calcium reacted was equal to (0.40 g)/(40.1 g/mol) = 0.01 mol.The amount of H2 formed was also 0.01 mol. At 1.0 atm and 27°C, the volume of 0.01 mol H2 = [(0.01 mol)(0.0821 L×atm/mol×K)(300 K)]/1.0 atm = 0.246 L = 246 mL.

Carvone is shown below with certain carbon atoms labeled. (+)-Carvone and (-)-carvone differ in the orientations of the substituents around which of the following carbon atoms? Carbon 2 only Carbon 5 only Carbons 2 and 5 only Carbons 2, 5, and 7 only

Carbon 5 is the only stereogenic carbon atom (chirality center); carbons 2 and 7 are not stereocenters. Thus, answer choice B is the best answer. KEY:::Double bond = lost of chiral center. So you wouldn' t count that C as a chiral center

If red litmus paper is dipped into the Na2CO3 solution, it will: remain red, because carbonate is an acidic salt. remain red, because sodium carbonate is neutral. Answer:: turn blue, because carbonate reacts with water to produce OH-. turn blue, because sodium ions form sodium hydroxide in water.

Correct Thinking: It'll turn moist litmus paper blue, as sodium carbonate is a basic salt (the carbonate anion hydrolyses when dissolved in water to produce hydroxyl ions and bicarbonate anions (and eventually H2CO3, a weak acid) H2O + (CO3)2- → HCO3- + OH- The hydroxyl ions are basic and so is the solution as a result, hence the blue litmus. Note: Production of OH or H changes the color

Which of the bromomethanes is LEAST polar? CBr4 CHBr3 CH2Br2 CH3Br Ans: CBr4

How to solve: Notice that they all cancel out

The term "ideal gas" refers to a gas for which certain assumptions have been made. Which one of the following assumptions applies to an ideal gas? The law PV = nRT2 is strictly obeyed. Intermolecular forces are infinitely large. Individual molecular volume and intermolecular forces are negligible. One mole occupies a volume of 22.4 L at 25°C and 1 atm pressure. Ans: Individual molecular volume and intermolecular forces are negligible.

Ideal gas laws It is assumed that the molecules in an ideal gas have no volume and that there are no interactions between the molecules. Thus, C is the best answer.

Which of the following is the most plausible explanation for the fact that the saponification of the triacylglycerol in the passage resulted in four different fatty acid salts? The triacylglycerol molecule consisted of four different fatty acid units. Glycerol was transformed into a fatty acid salt under the reaction conditions. One of the fatty acid salts was unsaturated, and it completely isomerized under the reaction conditions. One of the fatty acid salts was unsaturated, and a small percentage isomerized under the reaction conditions.

If one of the R groups in the triacylglycerol contained a carbon-carbon double bond and if isomerization of the double bond occurred during the saponification reaction, four fatty acids would be obtained instead of three.

Which one of the following general characteristics is shared by all catalysts? They induce more collisions among reactant molecules. They transfer kinetic energy to the reactant molecules. They increase the reaction rate but do not change the Keq of a reversible reaction. They increase both the reaction rate and the Keq of a reversible reaction.

In general, catalysts lower the activation energy of the slowest step in a reaction. Thus, they increase the rate of the reaction without increasing the number of collisions, the kinetic energy of the reactants, or the Keq of a reversible reaction. Thus, answer choice C is the best answer.

In the Bohr model of the atom, radiation is emitted whenever electrons: change orbits. undergo acceleration. move to orbits of lower energy. move to orbits of larger radius.

In the Bohr model of an atom, energy is emitted only when an electron falls from a higher to a lower energy level. Thus, answer choice C is the best answer.

What are the oxidizing and reducing agents, respectively, in the reaction below? 2HCl + H2O2 + MnO2 → O2 + MnCl2 + 2H2O H2O2; HCl H2O2; MnO2 MnO2; HCl MnO2; H2O2 Ans: MnO2; H2O2

In the reaction pictured, Mn is reduced from +4 to +2; therefore, MnO2 is the oxidizing agent. O is oxidized from -1 in H2O2 to 0 in O2; therefore, H2O2 is the reducing agent. Always assign oxidation for first letter then second letter. Ex: H2O2 assign for H first then O

Which of the following atoms has the largest first ionization energy? Potassium Zinc Gallium Krypton

Krypton, a noble gas, has a complete outer shell of electrons and therefore has an extremely high ionization energy. Potassium, with only one electron in its outermost shell, has a low ionization energy.

anomeric carbon

Location where alpha and beta differences can be recognized

Which of the following is the most likely reason that plants CANNOT utilize nitrogen from the atmosphere? N2 is present in very low concentrations in the atmosphere. N2 is too polar. N2 is very unreactive because it is a noble gas. N2 is very unreactive because of the great strength of the N≡N triple bond.

Molecular nitrogen is normally a very unreactive molecule, because of the very strong triple bond holding the nitrogen atoms together, as stated in answer choice D. Since plants require nitrogen in a reduced form, this would be the main reason for their inability to utilize nitrogen directly from the air. The other responses are readily eliminated. Nitrogen is the most abundant element in the air, so A is incorrect. Because the two nitrogen atoms in N2 are identical, and have the same electronegativity, the molecule is not polar at all, and B is incorrect. Finally, N2 is not classified with the noble gases, which are in group 8 of the periodic table. Thus, answer C is incorrect as well. Thus, answer choice D is the best answer.

How much sodium hydroxide is needed to completely saponify a triacylglycerol? A catalytic amount, because OH- is continuously being regenerated during saponification One-third of an equivalent, because each OH- ion reacts to form three fatty acid salts One equivalent, because each OH- ion reacts to produce one molecule of glycerol Three equivalents, because one OH- ion is required to saponify each of the three fatty acid groups

One hydroxide ion is required to hydrolyze one ester linkage of a triacylglycerol molecule. Because there are three ester linkages in a triacylglycerol, three equivalents of sodium hydroxide will be needed to completely saponify the triacylglycerol.

According to the passage, which of the following compounds can the worker use to catalyze the cleavage of a triglyceride? HCl(aq) NaCl(aq) NaOH(aq) Na2SO4(aq)

Only NaOH is a base and can catalyze the saponification of an ester

Chemical reactions

Rates of chemical reactions always increase with increasing temperature, since a greater number of molecules possess enough energy to overcome the energetic barrier to reaction - the activation energy - at higher temperature.

Vaccum Distillaiton

Separates boiling point above 150 celcius apart

A sparingly soluble metal hydroxide, M(OH)2 has a molar solubility of S mol/L at 25°C. Its Ksp value is: S2. 2S2. 2S3. 4S3.

The Ksp for a substance, AaBb, equals [A]a[B]b. The Ksp for M(OH)2 = [M][OH-]2. If the solubility of M(OH)2 is S mol/L, then [M] = S mol/L and [OH-] = 2S mol/L. The Ksp = S(2S)2 = S(4S2) = 4S3.

What is the best explanation for the fact that a solution of NaNO2(aq) is basic? NO2- is hydrolyzed with the formation of OH -(aq) ions==Answer Na+ is hydrolyzed with the formation of OH -(aq) ions. NaNO2(aq) decreases the Ka of HNO2(aq). NaNO2(aq) increases the Ka of HNO2(aq).

The NO2- reacts with water, forming OH- ions. So when you get these type of questions about salts first spilt up the compound. So you have NO2- and Na+, solvated by water when dissolved. Dissect the activities of these ions in water. Sodium is a cation associated with strong base (NaOH, Na2O) or the conjugate acid of strong bases (a weak Lewis acid) so it's usually a spectator ion and it will exist in the solution solvated by water molecules undisturbed. However NO2- is the conjugate base of a weak acid, therefore it is mildly basic and it would hydrolyze H2O into OH- and the weak Acid HNO2. And since the basicity of the OH- outweighs HNO2's acidity, NaNO2 will make a solution basic.

When aqueous solutions of the various anions and cations were mixed, precipitates formed because: few aqueous solutions can contain more than one cation or anion. the anions precipitated as solid metals. the solubilities of cations were decreased by the other cations. the solubility product of a compound was exceeded.

The amount of a substance that will dissolve in water is described by the Ksp. The Kspfor a substance, AaBb, equals [A]a[B]b. If the amount of the compound present is in excess of the Ksp, then a precipitate would form to maintain the Ksp.

What formula is the same for compounds 1 and 2? Valence-bond Empirical Molecular Structural

The empirical formula of a compound gives the relative number of atoms of each element it contains. Thus Compound 1, B2P2H2N2R4, has the same empirical ratio (1B:1P:1H:1N:2R) as does Compound 2, B3P3H3N3R6 where R = C3H7. The molecular formula represents the actual composition of the molecule. The valence-bond and structural formulas represent the actual structure of the molecule and cannot be the same for molecules with different absolute numbers of atoms. The correct answer is B.

tautomerism

The equation shows the migration of a hydrogen atom from an α-carbon atom to an oxygen atom. The hybridization of the α-carbon atom and oxygen atom change during the process.

ionization constant

The equilibrium constant for the ionization of a weak acid or weak base.

equilibrium constant

The equilibrium constant is given by the product of the concentrations of all the product species, divided by the product of the concentrations of all reactant species, with each concentration raised to a power that corresponds to the stoichiometric coefficient in the balanced reaction. Thus, for the general reaction: pA+qB⇌rC+sD the equilibrium constant Keq would be written as: Keq=[C]r[D]s/[A]p[B]q

Ignoring stereochemistry, how many different tripeptides may exist that contain the same three amino acids as the molecule shown below? 1 3 6==Ans 9

The formula for the number of possible peptides that contain one each of n amino acids is n! (n factorial). For n = 3 (a tripeptide), n! = 3! = 3 × 2 × 1 = 6 = Answer C. Alternatively, for a tripeptide ABC, the following combinations are possible: ABC, ACB, BAC, BCA, CAB, and CBA, or six = Answer C.

Ideal Gas laws

The ideal gas law assumes that molecular volumes and intermolecular attractive forces are negligible.

Ba2+(aq) is an ion that is very toxic to mammals when taken internally. Which of the following compounds, mixed in water, would be the safest if accidentally swallowed? BaSO4, Ksp = 1.1 × 10-10 BaCO3, Ksp = 8.1 × 10-9 BaSO3, Ksp = 8.0 × 10-7 BaF2, Ksp = 1.7 × 10-6

The lower the value of Ksp is, the lower the concentrations of the cation and anion in an aqueous solution and the lower the solubility of the compound in water. If mixed with water and accidentally swallowed, the Ba salt with the lowest value of Ksp would be the safest.

Where are nonmetals found in the periodic table? Right side==Ans Left side Top half Bottom half

The noble gases and halogens are found on the right side of the table. These are nonmetals. Thus, A is the best answer.

What is the sum of the protons, neutrons, and electrons in strontium-90? 90 126 128== Ans 218

The number of protons in the nucleus of an element is given by the atomic number. In a neutral atom, the number of electrons is equal to the number of protons. The number of neutrons can be found by subtracting the atomic number from the mass number. The atomic number of strontium (Sr) is 38; so the number of neutrons is 90 - 38 = 52. The sum of protons, neutrons, and electrons in strontium is 38 + 38 + 52 = 128.

What is the oxidation number of aluminum in Na[Al(OH)4](aq)? +1 +2 +3 +4

The oxidation number of Na is +1, and the charge on a hydroxide ion is -1. For the compound to be neutral, aluminum would have to have an oxidation number of +3. note: dont separate polyatomic ion. OH is a polyatomic ion so u treat them together

To a first approximation, the ionization constant of H2S is: near zero. much less than 1. about 1. much more than 1.

The passage states that H2S is a weak acid. A weak acid is one that dissociates in water, but only to a very small extent. For example, the dissociation constant of the weak acid acetic acid is 1.8 x 10-5. This is much less than one, but is measurably non-zero.

How many dietary calories does a 1-g sample of Olestra contribute to a human consumer? 0 Cal 4 Cal 5 Cal 9 Cal

The passage states that Olestra is not metabolized because digestive enzymes are blocked from cleavage sites. If a molecule is not metabolized, it can provide no energy and thus no calories. Choice A, 0 Cal, is the correct answer. Pay attention to information given in passages

The structure and bonding of diamond, which is formed from graphite at extreme pressures, should be similar to that of elemental: aluminum and gallium. silicon and germanium. phosphorus and arsenic. sulfur and selenium.

The passage states that at extreme pressures an elemental solid assumes the structure and bonding characteristics of a heavier element in the same column of the periodic table. The structure and bonding of diamond, which is a form of carbon, would therefore be most like other elements in the same group of the periodic table as carbon. This group contains silicon and germanium. Thus, B is the best answer.

Which of the following changes in state functions occurred during the dissolution shown in Equation 1? ΔH < 0 ΔG > 0 ΔS > 0 I only II only I and III only II and III only

The passage states that the temperature increased during the preparation of the NaOH solution. Because heat is liberated, the dissolution of solid NaOH is an exothermic process for which the enthalpy change ΔH < 0. As NaOH dissolves, the system becomes more random (disordered), which corresponds to a positive entropy change, and ΔS > 0. The free energy change is given by ΔG = ΔH - TΔS and must be less than zero when the value of ΔH is negative and that of ΔS is positive, because the absolute temperature T is always a positive value. Thus, answer choice C is the best answer.

Which of the following pairs of compounds provides an example of ionic and covalent bonding, respectively? HBr(g) and NaCl(s) NaCl(s) and NaI(s) NaI(s) and NaCl(s) NaCl(s) and HBr(g)===Ans

The passage states that the vast majority of covalent compounds are comprised exclusively of nonmetallic elements, whereas binary ionic compounds are made up of a metal and a nonmetal. Sodium is a metal and chlorine is a nonmetal; consequently, NaCl is an ionic compound. Hydrogen and bromine are both nonmetals, which means HBr is a covalent compound. Thus, D is the best answer.

Compound 1 is a stronger acid than Compound 2 because the anion of Compound 1 is better stabilized by: resonance effect. dehydration. an inductive effect. Ans::::hydrogen bonding between OH and CO2

The question was testing the function of intramolecular forces. Intramolecular H-bonding will lower things like melting point because it reduces the ability to form intermolecular H-bonds. Intramolecularly, it will stabilize the conjugate base, making it a stronger acid.

The ion responsible for the color of the solutions is: sulfate, because sulfur has s and p orbitals. nickel(II), because it has a charge of +2. nickel(II), because it has unfilled d orbitals. sulfate, because it is a resonance-stabilized anion.

The solution containing nickel(II) ions is green-colored. The color arises because nickel(II) ion has partially filled d orbitals and the electrons in the lower energy d orbitals absorb visible light to move to the higher energy d orbitals. Other thinking: Electron movement across unfilled orbitals, particularly d orbitals due to their energy states, tend to produce colored compounds. When colors are discussed in AAMC think D orbitals. Because they have the ability to absorb visible light

How many sodium ions are in the initial 50.00-mL solution of Na2CO3? 1.50 × 1022 Answer ==3.00 × 10^22 6.02 × 1023 12.0 × 1023

The solution contains 7.15 g Na2CO3×10H2O. 1. Dividing by the molar mass will give the number of moles: (7.15 g)/(286.14 g/mol) = 0.0250 mol. 2. Because each mole of Na2CO3×10H2O contains 2 mol Na+, there is 0.0500 mol Na+. 3. Using Avogadro's number, the number of sodium ions is (0.0500 mol)(6.02 × 1023 ions/mol) = 3.01 × 10^22 ions.

Alcohols generally require acid catalysis in order to undergo substitution by nucleophiles. The acid catalyst enhances the reaction by: increasing the solvent polarity. creating a better leaving group. neutralizing basic impurities. protecting the alcohol group.

This question asks the examinee to remember that the substitution reaction in question serves to replace the hydroxyl group and that hydroxide ion is one of the worst leaving groups in substitution reactions. Under acidic conditions, the hydroxyl group is protonated such that the leaving group is now water, a superior leaving group, rather than hydroxide ion. Thus, B is the best answer. Solvent polarity and basic impurities are not particularly relevant, and protecting the alcohol group defeats the purpose of the reaction.

The most likely function of the ebulliator is to: keep the condensed vapors cool in the receiving flask. promote the establishment of a high vacuum in the system. prevent superheating of the liquid to be distilled. provide an outlet when the pressure inside the system becomes too high. Ans: Prevent superheating of the liquid to be distilled

To answer this question The passage mentions that the ebulliator was added to introduce small air bubbles into the system. This is the same function provided by a boiling chip at atmospheric pressure. The air bubbles break the surface tension of the liquid being heated and prevent superheating and bumping.

Which of the following properties is associated with the existence of glycine as a dipolar ion in aqueous solution? High dipole moment High molecular weight Low dielectric constant Low solubility in water Ans: High Dipole moment

To answer this question, The "dipolar ion" part is key. That statement tells you that they are talking about glycine in its zwitterionic form. In other words, it has a negative charge that is separated from a positive charge, which thus creates a large dipole moment.

If a leak develops in the vacuum distillation apparatus, the boiling points of the two components of caraway seed oil will: Answer----both increase. both decrease. both remain the same. become more similar.

To answer this question: 1)Know the definition of the boiling point: ----The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the surface pressure. The normal boiling point is measured at 1 atm pressure. 2) Vapor Pressure The vapor pressure of a liquid increases with increasing temperature. Hence, the boiling point of a liquid decreases as the pressure on the surface of the liquid is decreased. If a leak develops in the apparatus, the surface pressure will increase, as will the boiling points of both liquids. Thus, answer choice A is the best answer.

As an alternative to Experiment 2, the chemist also can improve the yield of the polymer obtained in Experiment 1 by increasing the amount of: H2O. PNP. Mg2+. CDP.==Ans

To approach questions like this, consider LeChatelier's Principle, if the equilibrium system is stressed, the system responds in a way to counteract that stress. However, when a catalyst is part of the equation, know they DO NOT affect the amount of product created. If a catalyst is used in such a reaction, it will only change the rate of attaining the equilibrium ratio of products and reactants; it will not change the equilibrium ratio. Thus, adding excess PNP and Mg2+, which act as catalysts, will have no effect on the amount of product formed, and responses B and C are incorrect.

A student uses thin layer chromatography on silica plates to monitor the progress of the reaction below. Does the product have a higher or lower Rf than the starting material? Higher, because the product is more polar than the starting material Higher, because the product is less polar than the starting material Lower, because the product is less polar than the starting material Ans::Lower, because the product is more polar than the starting material

To correctly answer this question, determine if the stationary phase is polar or nonpolar,. Once you do, then you decide what happens to the Rf. The OH group is more polar than the ketone group and thus will interact more strongly with the stationary phase(silica). Therefore, the product will move less farther on the silica plate leading to a low Rf value. Higher Rf values mean that the product spotted on the TLC moves farther

A compound was analyzed and found to contain 12.0 g carbon, 2.0 g hydrogen, and 16.0 g oxygen. What is the empirical formula for this compound? CH2O C6HO8 C6H12O6 C12H2O16 Ans: CH2O

To solve you have to pay attention to whats given in the question stem. The question gives you grams of atoms. Empirical formula focuses on moles. ---As a result you have to change 12g C, 2g H and 16g O to moles. The number of moles of carbon in 12.0 g C is 12/12 = 1; of hydrogen in 2 g H = 2/1 = 2; and of oxygen in 16 g O = 16/16 = 1. Therefore, the compound contains a 1:2:1 molar ratio of C:H:O, giving the formula C1H2O1, or simply CH2O. This formula is the empirical formula because the subscripts cannot be further reduced by a division by two.

Simple Distillation

Used to separate two liquids with boiling points below 150 celcius and at least 25 celcius apart

When glycerol reacts with three different fatty acids, how many stereogenic centers does the product triacylglycerol contain? 0 1 2 3

When glycerol reacts with three different fatty acids, only carbon 2 in the resulting triacylglycerol is attached to four different groups.

Which of the following shows the electron configuration of chlorine in NaCl? 1s22s22p63s23p4 1s22s22p63s23p5 1s22s22p63s23p6 1s22s22p63s23p44s2 Ans: 1s22s22p63s23p6

When sodium (Na) and chlorine (Cl) are combined, the sodium atoms each lose an electron, forming cations (Na+), and the chlorine atoms each gain an electron to form anions (Cl−). These ions are then attracted to each other in a 1:1 ratio to form sodium chloride (NaCl). Yep. Needs to be Cl- for NaCl to form ionic bond.

What is the pH of a .001 M NaOH solution? .001 3 7 11 Ans: 11

When you get questions like this, make sure you pay attention to if you have H or OH A .001 M NaOH solution has a pOH (-log [OH-]) of 3. The pH of the solution is therefore 14 - 3 = 11. Thus, D is the best answer.

polar Bond

a covalent bond between two atoms where the electrons forming the bond are unequally distributed.

Ionic Bond

most likely to form between elements of very high and very low electronegativity. In practice this generally means elements at the far right and far left of the periodic table respectively

Oxidation

occurs at annode in both electrolytic and galvanic cell

reduction

occurs at cathode in both electrolytic and galvanic cell

The pKa for the dissociation of H2PO−4 to HPO2−4 is 6.7. What is the initial ratio of [HPO2−4]:[H2PO−4] in the buffer solution of Experiment 1? 1:1 2:1 100:1==Ans 200:1

pH=pKa+log([conj. base]/[conj. acid]) or pH=pKa+log([HPO−24]/[H2PO−4]) This logarithmic version is called the Henderson-Hasselbalch equation, but it is really just a rearrangement of the Ka expression. For this problem, 8.7=6.7+log([HPO−24]/[H2PO−4]) or 2.0=log([HPO−24]/[H2PO−4]) Taking the antilog, 102=[HPO−24]/[H2PO−4] Thus, at the beginning of the reaction in Experiment 1, the ratio [HPO−24]:[H2PO−4]=100:1

Fractional distillation

separates liquids with close boiling points. Less than 25 celcius apart

Empirical Formula

shows the lowest whole number ratio of moles of each element in a mole of the compound, or the corresponding number of atoms per molecule.

catalyst

substance that speeds up the rate of a chemical reaction

ionization potential

the energy required to remove an electron from an atom is the ionization potential.

First Ionization Energy

the energy required to remove an electron from the outer shell of an atom. For any given period, it is lowest when the removal of the electron results in a complete shell or subshell, and highest when the removal of the electron disrupts a complete shell or subshell.

boinling point

the temperature at which the vapor pressure of the liquid equals the surface pressure