Mixed Concepts Flashcards

Question

A graphical representation of measuring signal as a function of quantity of analyte. A. Calibration curve B. Quality Control Chart C. Absorbance Chart D. None of the above

Answer 1

A. Calibration curve

Answer 2

D. 32 Maximum number of electrons=2n^2

Answer 3

D. plumbic hypochlorite perchlorate - ClO4

Answer 4

B. not lean on the balance bench, close the draft doors on the balance and zero the balance prior to weighing To ensure accuracy, external factors like air drafts and vibrations must be minimized, and the balance must be properly zeroed before weighing.

Answer 5

D. Volatile liquids can be weighed by getting the mass of the empty vial with cap first This method, known as "weighing by difference," ensures that the volatile liquid's mass can be determined accurately, since the liquid may evaporate during the weighing process if left open. C is incorrect: Using a metal spatula to transfer solid reactants is generally discouraged, especially in analytical chemistry. Metal spatulas can react with certain chemicals or cause contamination. Instead, non-reactive materials like plastic or ceramic spatulas are recommended for transferring solid reactants.

Answer 6

C. Keep the eye level with the bottom of the meniscus and record that reading For accurate readings, the eye should be level with the bottom of the meniscus (the curve formed at the surface of the liquid). This minimizes parallax error and is the standard procedure for reading liquid levels in volumetric glassware. Parallax error refers to the difference in the apparent position of an object viewed along two different lines of sight.

Answer 7

A. Frosted band

Answer 8

B. vapor pressure When choosing a solvent for crystallization, factors like solubility (how well the material dissolves), reactivity (whether the solvent reacts with the material), and polarity (which affects solubility) are important. Vapor pressure is not typically a key factor in selecting a crystallization solvent, so it's the exception here.

Answer 9

A. clear solution After filtration in a crystallization process, any impurities or undissolved solids are removed, leaving behind a clear solution that contains the dissolved material. This solution is then cooled to allow the material to crystallize out.

Answer 10

C. Allowing the hot solution to cool slowly and let crystals grow The key step in recrystallization is the slow cooling of the hot solution, which allows the dissolved solid to form pure crystals. During slow cooling, impurities remain in the solution while the purified substance crystallizes out. This step is crucial for obtaining high-quality crystals.

Answer 11

A. Purification of alum A. Purification of alum: This is an example of crystallization. The impure alum is dissolved in water, and then pure alum crystals form as the solution cools. B. None of the given answers: This option suggests no correct answer, but in this case, A is the correct one. C. Separation of gases from air: This is done by distillation or fractional distillation, not crystallization. Different gases are separated based on their boiling points. D. Purification of seawater: This is usually done by distillation or reverse osmosis, which removes salt and impurities from water, not by crystallization.

Answer 12

A. Thermal

Answer 13

C. II and III only

Answer 14

A. liquid solvent such as isopropanol In thin layer chromatography (TLC), the mobile phase is the liquid solvent that travels up the thin layer of stationary phase (which is often a coating of silica gel on a plate). The solvent carries the sample along the plate, allowing for the separation of different components based on their affinities to the stationary and mobile phases.

Answer 15

A. Retardation factor

Answer 16

D. Glass Thin layer chromatography (TLC) plates, also known as chromatoplates, are typically made of glass. The glass plates are coated with a thin layer of stationary phase material, such as silica gel or alumina, which facilitates the separation of components during the chromatography process.

Answer 17

D. rate of movement of solute

Answer 18

C. all of the given answers

Answer 19

C. increasing polarity and increasing distribution ratio

Answer 20

A. Benzene will be eluted first Large value of D = solute has a higher affinity for the stationary phase (gamay ang value sa denominator-concentration sa mobile phase)

Answer 21

A. Gas chromatography GAS CHROMATOGRAPHY separate and analyze compounds that can be vaporized without decomposition. It’s often used for volatile mixtures. PAPER CHROMATOGRAPHY A sample is separated on paper using a liquid solvent (mobile phase). For non-volatile mixtures (like inks or dyes)

Answer 22

B. Adsorption In gas-solid chromatography, the stationary phase is a solid material that adsorbs the components of the gas mixture onto its surface. The separation occurs based on the different affinities of the components for the solid phase. Compounds that are more strongly adsorbed will take longer to pass through the column, while those that are less strongly adsorbed will elute faster.

Answer 23

D. Gel permeation Why the other options are less suitable: A. Gas-liquid chromatography: This is used for volatile, low molecular weight compounds, not high molecular weight substances. B. Gel filtration: This is also a form of size-exclusion chromatography, but it is typically used for water-soluble compounds, not for those soluble in nonpolar solvents. C. Ion-exchange chromatography: This is used for separating charged molecules based on their affinity to a charged stationary phase, and is not ideal for nonpolar, high molecular weight compounds.

Answer 24

C. all of the given answers

Answer 25

C. all of the given answers

Answer 26

A. all of the given answers Molecular spectroscopy has several applications, including: Basis of understanding of colors: It helps explain how molecules absorb and emit light, which is related to color. Structural investigation: Spectroscopy is used to determine the structure of molecules by analyzing how they interact with electromagnetic radiation. Study of excited reaction products: It allows the study of molecules in excited states and how they behave in chemical reactions.

Answer 27

D. All of the given choices.

Answer 28

B. 10 to 400 nm A. 400 nm to 700 nm- visible light spectrum B. 10 to 400 nm- This is the correct range for ultraviolet (UV) radiation. C. 700 nm to 1 mm- This range falls within the infrared (IR) spectrum D. 0.01 nm to 10 nm- This range corresponds to X-rays and part of the gamma-ray spectrum.

Answer 29

D. They absorb strongly at 800 nm. Explanation: A. They may contain extensive conjugated double bonds.: This is true. Chromophores often have conjugated systems that allow them to absorb light. B. They contain unsaturated functional groups.: This is also true. Chromophores typically include unsaturated bonds (like double or triple bonds) that contribute to their ability to absorb light. C. They are added to ions that do not strongly absorb light in the UV-Visible region.: This statement is true as well. Chromophores can be used to enhance the light absorption properties of certain ions or compounds. D. They absorb strongly at 800 nm.: This is generally NOT true for most chromophores. The absorption of light typically occurs in the UV-Visible region (approximately 200-700 nm), and while some chromophores can absorb in the near-infrared region, strong absorption at 800 nm is not a common characteristic.

Answer 30

D. They interfere in the transition of the electrons of the analyte.

Answer 31

B. The cuvette is not wiped off before it is inserted into the spectrophotometer.

Answer 32

A. Atomic Absorption Spectroscopy

Answer 33

C. spectroscopy The equilibrium constant for the reaction can be best determined using spectroscopy, particularly UV-Vis spectroscopy. The formation of the complex ion produces a colored solution that can be quantitatively measured. By measuring the absorbance of the solution at the specific wavelength where the complex absorbs light, you can determine the concentration of the complex and, thus, the equilibrium constant.

Answer 34

C. Infrared Spectroscopy

Answer 35

C. 4000 to 2500 cm-1 Summary of the Regions: 4000 to 2500 cm⁻¹: Stretches of N-H, O-H, and C-H. 2500 to 2000 cm⁻¹: Generally less relevant for these functional groups. 2000 to 1500 cm⁻¹: Typically contains the region for C≡C or C=O stretching, but not for N-H, O-H, or C-H stretching. 1500 to 1000 cm⁻¹: This is primarily where bending motions occur but is not where the stretching motions for these groups are primarily found.

Answer 36

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Answer 37

B. a nucleophile Cyanide (CN⁻) has a lone pair of electrons and attacks the electrophilic carbon in 1-bromobutane, leading to the substitution reaction. This is the correct role of cyanide in this reaction.

Answer 38

C. Either I or II The molecule with the formula C₅H₁₀O can contain: Alcohol (I): This functional group has an -OH (hydroxyl) group. The presence of an -OH is possible in compounds with this formula. Ketone (II): This functional group has a carbonyl group (C=O) between two carbon atoms. A ketone is also compatible with the formula C₅H₁₀O.

Answer 39

B. nucleophilic addition

Answer 40

A. Lewis acid A Lewis acid is a substance that can accept an electron pair. AlCl₃ can accept electron pairs from aromatic compounds, facilitating the alkylation reaction. This is the correct answer.

Answer 41

B. acetaldehyde When a primary alcohol reacts with a mild or weak oxidizing agent, it is typically oxidized to an aldehyde. For example, ethanol (a primary alcohol) will oxidize to acetaldehyde when treated with a mild oxidizing agent.

Answer 42

A. benzoic acid KMnO₄/H₃O⁺ is a strong oxidizing agent that can oxidize benzyl alcohol (C₆H₅CH₂OH) to benzoic acid (C₆H₅COOH). The oxidation process involves converting the primary alcohol group (-OH) into a carboxylic acid group (-COOH).

Answer 43

A. reaction with FeCl3 Phenols react with ferric chloride (FeCl₃) to form a colored complex, usually purple or violet. This test is specific for phenols and is often used as a qualitative test to identify them.

Answer 44

C. Ether: A. Carboxylic acid: Carboxylic acids have strong hydrogen bonding due to the -COOH group, which makes them less volatile. B. Alcohol: Alcohols also have hydrogen bonding, which decreases their volatility compared to ethers. C. Ether: Ethers have weaker intermolecular forces (mainly Van der Waals forces) and do not form strong hydrogen bonds like alcohols or carboxylic acids. This makes them more volatile. D. Aldehyde: Aldehydes have moderate volatility, but they also have dipole-dipole interactions and some hydrogen bonding, making them less volatile than ethers.

Answer 45

C. butanoic acid Among the given options, butanoic acid has the highest boiling point due to the presence of a carboxylic acid functional group. Carboxylic acids can form strong hydrogen bonds between molecules, which significantly increases their boiling point compared to ketones.

Answer 46

A. unpleasant odor Amines are known for having strong, often unpleasant odors (like fishy smells), so this property is true for many amines, including those with the formula C₄H₁₁N.

Answer 47

D. Add small portions of hot water to benzoic acid while stirring until benzoic acid dissolves.

Answer 48

D. glass beads

Answer 49

A. a lower temp than its boiling point When steam is introduced, it lowers the partial pressure of the organic liquid, allowing it to vaporize at a lower temperature than its normal boiling point.

Answer 50

A. substance from baseline to distance moved by solvent from baseline

Answer 51

B. The reactions taking place are non-spontaneous. In galvanic cells, the reactions are spontaneous. They convert chemical energy from the spontaneous redox reactions into electrical energy.

Answer 52

B. anode-iron; cathode-copper

Answer 53

A. absorbance is proportional to both the path length and concentration of the absorbing species

Answer 54

D. Radiation is absorbed by non-excited atoms in vapor state and are excited to higher states. A. Color is measured: This is not accurate for AAS, as it does not measure color but rather specific absorption at certain wavelengths. B. Color is simply observed: This option does not describe the quantitative nature of AAS. C. Medium absorbs radiation and transmitted radiation is measured: This statement is more relevant to techniques like UV-Vis spectroscopy, not AAS.

Answer 55

D. I, II, and III I. Analyte molecules are converted to gaseous ions: True. In mass spectrometry, the substances being analyzed are turned into ions that are in gas form. II. The ions are separated according to their mass-to-charge ratio: True. Ions are sorted based on how much they weigh compared to their charge. III. Mass spectra can be used to find precise isotopic masses and ratios: True. Mass spectrometry can identify different isotopes and their amounts in a sample.

Answer 56

D. Radio frequency

Answer 57

D. All of the above

Answer 58

B. Affinity chromatography

Answer 59

A. dissolved in volatile liquids In gas chromatography (GC), solid samples must be in a suitable state for them to be effectively analyzed. Since solid samples cannot be directly injected into the GC column, they need to be converted into a volatile form.

Answer 60

D. sensitive to the changes in the flow rate of a carrier gas

Answer 61

B. Electron capture detector This type of detector is highly sensitive to electronegative compounds, such as chlorinated pesticides and polychlorinated biphenyls (PCBs). It operates by capturing electrons from a radioactive source, and when an analyte with an electronegative atom passes through, it captures some of those electrons, resulting in a measurable current. This makes ECD particularly effective for detecting halogenated compounds.

Answer 62

D. It allows entry of particles that cause precipitation upon contact with stationary or mobile phase.

Answer 63

B. capillary column While capillary columns are commonly used in gas chromatography (GC) due to their narrow diameter and efficiency in separating volatile compounds, they are not typically used in liquid chromatography (LC) or high-performance liquid chromatography (HPLC). In liquid chromatography, the columns are generally larger in diameter to accommodate liquid mobile phases.

Answer 64

A. Thermal

Answer 65

D. All of the above.

Answer 66

A. All methods given are unacceptable.

Answer 67

A. Pour acid into water. This is the correct procedure because it minimizes the risk of an exothermic reaction that can occur when acid is mixed with water. When acid is added to water, it dilutes gradually, reducing the heat generated and preventing splattering. Pouring water into acid can cause the acid to splash due to the rapid heat release, which can lead to dangerous situations.

Answer 68

B. all of the given answers

Answer 69

A. electron-poor species

Answer 70

D. free-radical substitution

Answer 71

B. 1-chloropropene

Answer 72

D. aqueous solution of potassium permanganate C. Ammoniacal solution of silver nitrate: This is used for other reactions, like testing for alkynes, but not for alkenes. D. Aqueous solution of potassium permanganate: This is Baeyer's reagent. It is used to oxidize alkenes and can help identify them by causing a color change (purple to colorless).

Answer 73

C. 1-hexene The ability of a compound to decolorize bromine (Br₂) in a solvent like dichloromethane (CH₂Cl₂) typically indicates the presence of unsaturation (double or triple bonds). Unsaturated compounds react with bromine in an electrophilic addition reaction, leading to the formation of dibrominated products and resulting in the loss of the characteristic reddish-brown color of bromine.

Answer 74

A. Propyne is deprotonated by NaNH2, while propene is not. Propyne (which has a triple bond) has an acidic hydrogen that can be removed by sodium amide (NaNH₂), whereas propene (with a double bond) does not have such an acidic hydrogen.

Answer 75

C. styrene

Answer 76

D. 12σ and 3π

Answer 77

D. -NH2 In electrophilic aromatic substitution (EAS), substituents on the benzene ring can either activate or deactivate the ring towards further substitution reactions. Activating groups increase the electron density on the ring, making it more reactive toward electrophiles. Activating Groups: D. -NH2 (Amino group): This group is a strong activating substituent due to its ability to donate electron density to the benzene ring through resonance, significantly increasing the reactivity of the ring towards electrophiles.

Answer 78

B. isopropyl benzene This compound (also known as cumene) cannot be formed from the reaction of benzene with CH₃Cl and AlCl₃ because it would require the introduction of a propyl group rather than a methyl group.

Answer 79

C. electrophilic carbon and a good leaving group

Answer 80

B. one-step nucleophilic substitution involving both alkyl halide and nucleophile

Answer 81

B. (CH3)2CHX A. CH₃X: This is a primary alkyl halide, which can undergo SN2 but not SN1 due to lack of carbocation stability. C. (CH₃)₃CX: This is a tertiary alkyl halide that primarily undergoes SN1 and does not undergo SN2 due to steric hindrance. D. (CH₃)₃CCH₂X: This secondary alkyl halide can also undergo both mechanisms but is less common as the carbocation is stabilized by the tertiary group.

Answer 82

D. SN2 reactions

Answer 83

D. CHCH2CH2OH The correct answer should actually be D. CH₃CH₂CH₂OH (1-Propanol) due to the strong hydrogen bonding it can form, which is generally stronger than the dipole-dipole interactions in acetone (letter C)

Answer 84

D. oxidation of secondary alcohols This will produce ketones.

Answer 85

D. carboxylic acids

Answer 86

B. esterification

Answer 87

C. aqueous FeCl3

Answer 88

a. Buffer Solutions

Answer 89

b. Matrix Spike

Answer 90

c. Systematic Error

Answer 91

b. analyte

Answer 92

d. All of the above

Answer 93

d. All of the above

Answer 94

c. Electrolysis

Answer 95

c. Saturated solution

Answer 96

d. Milk and water Distillation is a process that separates components in a mixture based on their different boiling points. It works well for substances that are miscible liquids or liquid mixtures containing volatile and non-volatile components. a. Acetone and water: Can be separated by distillation because acetone has a much lower boiling point (56°C) than water (100°C). b. Aniline and chloroform: Can be separated by distillation as they have significantly different boiling points (aniline: 184°C, chloroform: 61°C). c. Impurities in seawater: Distillation can be used to separate water from dissolved salts and impurities by vaporizing the water and condensing it, leaving the impurities behind. d. Milk and water: Cannot be separated by distillation because milk is not a simple liquid mixture; it is an emulsion containing fats, proteins, and water. When heated, milk components would break down, and separation via distillation would not be feasible.

Answer 97

c. Differential adsorption

Answer 98

c. The greater the polarity of solute, more strongly it will be adsorbed on a polar surface

Answer 99

c. Different compounds are adsorbed on an adsorbent to different degrees

Answer 100

b. Paper chromatography

Answer 101

c. Gas chromatography a. Ion exchange chromatography: Primarily used for separating and purifying ions and polar molecules based on their affinity to the ion exchange resin. It's not typically used for quantitative analysis. b. Thin layer chromatography (TLC): A qualitative technique used for separating mixtures, but it can also be used for semi-quantitative analysis. However, it’s less precise than other methods for quantitative analysis. c. Gas chromatography (GC): Highly suitable for quantitative analysis because it allows for precise measurement of the concentration of volatile compounds in a sample. It provides high resolution and sensitivity, making it ideal for determining the amounts of components in a mixture. d. Liquid chromatography (LC): While also capable of quantitative analysis, it can be less effective for certain applications compared to gas chromatography, particularly for volatile substances.

Answer 102

b. Freezing point of liquid

Answer 103

c. Spectroscopic methods require less time and less amount of sample than classical methods

Answer 104

d. Borosilicate

Answer 105

a. Halogenated waste disposal is more costly.

Answer 106

d. None of the above a. 1 g/L PCl5 (Phosphorus pentachloride): This compound is a hazardous material and can produce toxic gases when reacting with water. Therefore, it should not be disposed of down the drain. b. 1 M H2SO4 (Sulfuric acid): This is a strong acid and poses significant hazards, including corrosivity and the potential to cause damage to plumbing and the environment. It should not be disposed of down the drain. c. 200 g/L PCl5: This concentration of phosphorus pentachloride is even more hazardous than the 1 g/L solution and should not be disposed of down the drain for the same reasons.

Answer 107

b. Ideal gas must be replaced by van der waals

Answer 108

d. Cyclohexene

Answer 109

b. Conductor

Answer 110

C. Carbonyl compounds

Answer 111

c. Adsorption

Answer 112

A. HCl HCl is a polar molecule, which means it has a positive and a negative end, allowing for dipole–dipole interactions. The other options are either nonpolar (C6H6, CH4) or ionic (NaCl), which does not exhibit dipole–dipole interactions in the same way.