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Chemistry
Benzene, NMR, pH and Kinetics.
Question | Answer |
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Identify the Acid1-Base1 and Acid2-Base2 - A)Acid1= HNO3, Acid2= NO3-, Base1= H20, Base2= H3O+ or B)Acid1= H3O+, Acid2= HNO3, Base1= NO3-, Base2= H20 or C)Acid1= HNO3, Acid2= H3O+, Base1= NO3-, Base2= H20 | C) Acid1= HNO3, Acid2= H3O+, Base1= NO3-, Base2= H20 |
Define: Bronsted-Lowry Acid | A proton donor |
Explain the difference between 'LARGE Ka VALUE' and 'SMALL Ka VALUE' | A 'Large Ka Value' means a low pKa showing high dissociation meaning its a STRONG ACID and a 'Small Ka Value' means high pKa value showing low dissociation meaning its a WEAK ACID. |
Describe what is pH & use an equation to explain | pH is [H+], pH = -log[H+] |
Write an expression for Ka using HA <---> A- + H+ | Ka = [A-] [H+]/ [HA], remember: [Products]/[Reactants] |
Describe what the splitting means on a proton NMR spectrum | How many protons the adjacent carbon has (n+1) |
Explain what each peak on a C-13 spectrum represents | How many carbon environments are present |
Describe how resonance occurs | Need to mention: Strong magnetic field, Thoes with low energy will align with magnetic field, Low-energy radio-frequency radiation added. Nuclei will oppose release energy and flip back, This continues creating resonance |
Explain what is the D2O is used for | has the same chemical compound of water, but with an isotope, that doesn't produce NMR signal. Any peak due to -OH and -NH disapear |
How is NMR used medicine | MRI SCANS |
Define and give the units of: Rate of Reaction. | The increase or decrease in concentration of reactants per unit time. Unit: mol.dm^-3 s^-1 |
Define Half-Life. | Half-life is the amount of time needed for a reactant concentration to decrease by half compared to its initial concentration. |
Describe how Half-life is shown on a graph. | On the y axis go to 1/2 of the initial concentration + draw a horizontal line cutting the y axis + stopping where it meets the graph. Then draw a line from that down. Do the same for 1/2 of that concentration (so 1/4 of the initial concentration) + repeat |
What is the formula for calculating the units of the rate constant, k? | (mol.dm^-3)^[1-overall order].s^-1 |
Describe the graph of Ratio vs Time, with the order of 0. | A straight horizontal graph, with a gradient 0. |
What is the difference between the products of the reaction of Phenol with Dilute HNO3 and Conc HNO3? | The reaction with dilute HNO3 produces phenol with the NO2 on carbon 2 OR carbon 4. The reaction with conc HNO3 produces phenol with the NO2 on carbon 2, 4 and 6. |
List the conditions and reagents for the Nitration of Benzene and give the equation. | Catalyst: conc H2SO4 Reagent: conc HNO3 Condition: reflux @ 55 degrees celcius Equation: C6H6 + HNO3 —> C6H5NO2 + H2O |
What are 2,4-DNP and Tollen’s Reagent used for and describe observations? | 2,4-DNP: used to detect BOTH Aldehydes and Ketones, orange ppt forms if present. TR: distinguishes between an aldehyde and ketone. When an aldehyde is present a silver ppt forms. |
Why do Aldehydes form silver ppt with Tollen’s Reagent? | Aldehydes reduce [Ag(NH3)2]+ to silver metal as the solution is alkaline, the aldehyde itself is reduced to a salt of carboxylic acid. |
Give two uses of Phenol. | Any two of: Antiseptics, manufacturing pharmaceuticals, detergents and dyes. |