Dr. Bob
Dr. Bob
  • Видео 105
  • Просмотров 176 040
How can I help
So far I have only posted videos for my courses, Introductory Organic Chemistry and General Chemistry. I was wondering if anyone had any particular questions about chemistry. If so, maybe I will post a video with the answer. Thank you for supporting my channel. My most popular videos are about the common names of organic substituents and the mechanism for the nitration of aromatic groups.
Просмотров: 274

Видео

Making of soap: The Analysis (video 2 of 2)
Просмотров 1423 года назад
In this video some soap that we made from coconut oil and lye is analyzed with a comparison to commercial soap. The visual properties, basicity, and lathering of the two soaps are compared.
Making soap from coconut oil and lye
Просмотров 4393 года назад
In this video, a solution of coconut oil and sodium hydroxide is boiled down in the presence of ethyl alcohol to produce a beautiful white soap.
CHM 151 Enthalpy of formation of nitric acid
Просмотров 9213 года назад
This short video explains the definition of enthalpy of formation, gives an example of an equation that corresponds to the enthalpy of formation of nitric acid, and shows how to get the enthalpy change for the evaporation of water using enthalpy of formation values.
Limiting Reagent magnesium with silver nitrate
Просмотров 2233 года назад
This video explains which solids would be present when a 3.8g piece of magnesium reacts with 23.6 mL of a 0.2056 M silver nitrate solution. The equation is balanced, amounts of reactants and potential products are converted to moles, the limiting reagent is determined and the amount of leftover magnesium is calculated. The solids present at the end are product silver and leftover magnesium.
Limiting reagent aluminum and silver nitrate
Просмотров 2883 года назад
This is the answer to a recent quiz question on limiting reagents. Aluminum reacts with silver nitrate to give silver metal. Given the amounts of reactants present, the amount of silver metal that could be made is calculated. 1) Balanced chemical equation. 2) Convert to moles 3) Use mole ratios to answer the question. The amount of reactant used can be figured out from the amount of product made.
Limiting reagent sandwich problem
Просмотров 433 года назад
This video goes through the general steps for solving a limiting reagent problem using the familiar example of a sandwich. 1) Balanced chemical equation. 2) Convert units (to moles) 3) Use mole ratios to answer questions. We even explore the amount of reactants left over at the end of the reaction.
CHM 230 Recrystallization of salicylic acid 2of2
Просмотров 1,3 тыс.3 года назад
In this video a mixture of salicylic acid and urea is recrystallized to give pure salicylic acid. This video illustrates one method for recrystallization: dissolving the solids in a minimum of warm solvent and then cooling to induce crystallization. The final yield of dry crystals was 0.4213 g and its melting point was 155.8 to 157.7 degrees Celsius. Success!!
CHM 230 Recrystallization of salicylic acid 1of2
Просмотров 1,5 тыс.3 года назад
A mixture of salicylic acid and urea will be recrystallized using water to give pure salicylic acid. This video shows the determination of the melting point of the mixture and the preparation to do the recrystallization. Looking at melting points of contaminated and purified samples gives us an indication of the success of the purification. In the subsequent video (2 of 2), the recrystallizatio...
CHM 230 Alkanes and unsaturation
Просмотров 1,2 тыс.3 года назад
This video briefly describes alkanes that conform to the CnH(2n 2) rule as saturated, and how to tell when a hydrocarbon is not saturated. Each degree of unsaturation is either a pi bond or a ring. The formula for benzene is given, and its degree of unsaturation is calculated and explained.
HCl and CH3OH reaction mechanism
Просмотров 8 тыс.3 года назад
This video describes the mechanism for the reaction between hydrochloric acid and methanol, using standard arrows to explain the "electron pushing". The structures of the products are shown. The pKa values of the acid and the conjugate acid are compared to determine whether the reaction is reactant or product favored.
Comparison of acidity of compounds
Просмотров 643 года назад
In this video, pairs of compounds are compared to determine which is the most acidic, with approximate pKa values for each. Six factors can help us to explain the differences, the electronegativity, size and hybridization of the element directly attached to hydrogen, inductive effects, resonance effects and charge. All of these except hybridization are illustrated with these examples.
pKa and conjugate bases of common molecules
Просмотров 1113 года назад
This video shows the Lewis Dot Structures for common molecules and ions, gives the approximate pKa for each and shows the Lewis Dot Structure for each conjugate base. Removal of the acidic H transforms each acid into its conjugate base.
Predict pKa of CF3CH2OH
Просмотров 4823 года назад
This video shows how I would predict the pKa of trifluoroethanol by comparison to ethanol. The inductive effect of adding electronegative atoms in the molecule is shown, with the size of this effect determined by comparing acetic acid to trifluoroacetic acid. We predict the pKa of trifluoroethanol to be about 11, fairly close to its actual pKa, which is between 11.5 and 12.5, depending on who y...
Valence bond description of HCN
Просмотров 1,7 тыс.3 года назад
This is the answer to a recent exam question (Fall 2020) in which students were asked to use valence bond theory to describe the bonding in HCN. A Lewis Dot Structure, hybridization of the atoms and orbital picture are all discussed and illustrated.
Homework 2 acids and bases 3 10
Просмотров 963 года назад
Homework 2 acids and bases 3 10
CHM 230 Lewis Acids 3 9
Просмотров 713 года назад
CHM 230 Lewis Acids 3 9
CHM 230 Acid Base Reaction and pKa 3.8
Просмотров 1423 года назад
CHM 230 Acid Base Reaction and pKa 3.8
CHM 230 pKa list 3.7
Просмотров 1433 года назад
CHM 230 pKa list 3.7
CHM 230 predict acidity of aniline 3 6
Просмотров 2233 года назад
CHM 230 predict acidity of aniline 3 6
CHM 230 acidity of phenol 3 5
Просмотров 953 года назад
CHM 230 acidity of phenol 3 5
CHM 230 acidity resonance effects 3 4
Просмотров 913 года назад
CHM 230 acidity resonance effects 3 4
CHM 230 Acidity charge and inductive effects 3 3
Просмотров 1163 года назад
CHM 230 Acidity charge and inductive effects 3 3
VSEPR Quiz Answers
Просмотров 1073 года назад
VSEPR Quiz Answers
Exam 1 Answers Review Chapter
Просмотров 713 года назад
Exam 1 Answers Review Chapter
CHM 230 Three Factors that affect acidity 3 2
Просмотров 1223 года назад
CHM 230 Three Factors that affect acidity 3 2
CHM 230 Intro to acidity 3 1
Просмотров 1033 года назад
CHM 230 Intro to acidity 3 1
230 Simple Distillation 3 of 3 Unknown Liquid
Просмотров 2193 года назад
230 Simple Distillation 3 of 3 Unknown Liquid
230 Simple Distillation 2of2 Hexane
Просмотров 2243 года назад
230 Simple Distillation 2of2 Hexane
230 Simple Distillation 1of3 Setting up
Просмотров 1033 года назад
230 Simple Distillation 1of3 Setting up

Комментарии

  • @Ylb801
    @Ylb801 Месяц назад

    Thank you. It's very helpful.

  • @alfredomartin6266
    @alfredomartin6266 Месяц назад

    great, would get better with a black pen

  • @montana.shaban5
    @montana.shaban5 4 месяца назад

    Thank you so much, from Libya This is the first time I understand Alkyl group 😊😊

  • @anaseshmela8512
    @anaseshmela8512 5 месяцев назад

    YES!! This is very helpful thank you!

  • @ahoycaptain5065
    @ahoycaptain5065 5 месяцев назад

    Great video, one question though, do we consider the prefixes “iso,tert,sec” when naming compounds in alphabetical order?

  • @asasdfdd1238
    @asasdfdd1238 6 месяцев назад

    So does excess of sulphuric and nitric acid form tnt ?

  • @ezanadaniel9149
    @ezanadaniel9149 10 месяцев назад

    GREAT VIDEO

  • @resikin
    @resikin 11 месяцев назад

    And 1-methylethyl is the same as isopropyl 😎 Thank you!!!

  • @angelcastaneda9482
    @angelcastaneda9482 11 месяцев назад

    You saved me

  • @deepshah3220
    @deepshah3220 Год назад

    Dr bob sir please give me your whatsapp number because my organic chemistry is so poor so I can solve my query with your help

  • @MaazKhan-dt1ne
    @MaazKhan-dt1ne Год назад

    What is structure of isopropyl bromide and secondary propyl bromide

    • @DrBob-fp6gp
      @DrBob-fp6gp Год назад

      The easiest way to answer this is with drawings. The propyl group is small and does not have a "secondary propyl" version. If you apply logic, you would put the bromide on the secondary carbon of the propyl, which would give you the same exact thing as the "isopropyl bromide". An isopropyl group is one that is connected by the secondary carbon, so it is also the secondary propyl group. For more complicated groups, like butyl, there is more variation. Propyls can only be normal or isopropyl groups.

  • @iamgroot7684
    @iamgroot7684 Год назад

    God bless you i finally understand

  • @henryj.8528
    @henryj.8528 Год назад

    These videos are very helpful to hobbyists. I would like to see more on lab techniques. One thing I've learned from your videos is to use small samples. You used only a five grams of salicylic acid and very small glassware to do the demo. Many chem channels use 1000 ml flasks and lots of material. I just want to do the experiments--I'm not trying to make anything. IIRC, plutonium chemistry was worked out in a watch glass and the first sample was microscopic. So I am buying very small lab ware. It's also cheaper... But it's been a while since I was in a chem class so the actual techniques are helpful. (For example, where to actually place the thermometer's bulb.) I would be interested in something on simple chromatography, various organic solvents, cleaning up household products into useful reagents, sources of fairly safe, easily obtainable chemicals that still demonstrate various processes.

  • @henryj.8528
    @henryj.8528 Год назад

    Well done demo.

  • @Divingplainandsimple
    @Divingplainandsimple Год назад

    Does the concentration of HCl limit this reaction? Would 1M HCl cause this reaction or is conc. required.

    • @DrBob-fp6gp
      @DrBob-fp6gp Год назад

      There are two aspects of the HCl to consider. The concentration of HCl is in the rate law, so the higher the concentration, the faster the reaction will proceed. Secondly, the total amount of HCl will limit the reaction. In our experiment we use concentrated HCl and at least a 10% excess. In that way the HCl will not limit the reaction.

  • @summerandfall1362
    @summerandfall1362 Год назад

    This guy is too beast 🧠

  • @anjuliirvin5780
    @anjuliirvin5780 Год назад

    You are my new teacher

  • @princejaiswal4014
    @princejaiswal4014 Год назад

    Thanku so much sir you videos were really very helpful for me Love from India🇮🇳.

  • @tracydbz1
    @tracydbz1 Год назад

    Thank you so much Sir. You are a life saver ❤. Because I swear these teachers that they have as teachers is useless. They just fly through the PowerPoint with no thorough explanation.

  • @ghala38
    @ghala38 Год назад

    Thank uu

  • @abhay.maurya548
    @abhay.maurya548 Год назад

    Ya kyon se language hai

  • @roro-uh1hh
    @roro-uh1hh Год назад

    Hello, I'm a student at Istanbul University Cerrahpaşa, Department of Chemistry. Before the exam , your videos helped me a lot, thank you.

  • @On99123
    @On99123 Год назад

    if you still confused you can figure it out via this link ruclips.net/video/N0o2T7DKTw8/видео.html

  • @ayubkhdhr
    @ayubkhdhr Год назад

    Thanks 😊

  • @Kashi-ht6ii
    @Kashi-ht6ii Год назад

    I am from India. And you 🙏

  • @kazishahjalal6852
    @kazishahjalal6852 Год назад

    This is literally a masterpiece. The best explanation you would get. A wonderful analysis.

  • @cielosierra7145
    @cielosierra7145 Год назад

    oh bob, thank you

  • @samuelnguni5527
    @samuelnguni5527 Год назад

    So helpful

  • @makaymiller9309
    @makaymiller9309 2 года назад

    Great explanation

  • @annnjeri5858
    @annnjeri5858 2 года назад

    U r the best teacher one can ever ask for... this concept was driving me crazy 😌

  • @samanthaecotothermia7896
    @samanthaecotothermia7896 2 года назад

    This is incredibly helpful, thank you for explaining this in simple terms!

  • @Kemax01
    @Kemax01 2 года назад

    thanks Dr. Bob for this video

  • @sharmainecalicdan2360
    @sharmainecalicdan2360 2 года назад

    Thank you!

  • @firassiddiqui4392
    @firassiddiqui4392 2 года назад

    should have at least 10X the views shortest, yet most complete video, and takes the time to go over the whole mechanism after explaining it once to help better understand

  • @weareallcreaterssimham1962
    @weareallcreaterssimham1962 2 года назад

    I am from India...... thank you sir.....

  • @omarshdifat9602
    @omarshdifat9602 2 года назад

    Use a smaller pencil

  • @omarshdifat9602
    @omarshdifat9602 2 года назад

    Use a smaller pencil

  • @rjtheragegamer7877
    @rjtheragegamer7877 2 года назад

    very help ful

  • @xKroos6
    @xKroos6 2 года назад

    Amazing

  • @abdoulayeba2950
    @abdoulayeba2950 2 года назад

    Merci infiniment.

  • @aleksajoksimovic
    @aleksajoksimovic 2 года назад

    Hey, I just discovered your channel and I have to say I'm impressed by your teaching style. It's incredible when an experienced & devoted teacher knows how to make new and scary topics easy to understand and apply. Please keep up the great work! :)

  • @bobpopofficial
    @bobpopofficial 2 года назад

    This 47 minute video was interesting the whole way through!

  • @soichikurihara-piche2909
    @soichikurihara-piche2909 2 года назад

    Thank you a lot, easy and simple

  • @josephmorrissey6790
    @josephmorrissey6790 2 года назад

    ayo bro your mic is kinda trippy

    • @DrBob-fp6gp
      @DrBob-fp6gp 2 года назад

      I know, it is the crappy mic of the document camera. Just getting through Covid times with remote teaching, not exactly hi fidelity audio.

  • @jonniepalmer7802
    @jonniepalmer7802 2 года назад

    Why does the OH2 not just leave the methyl group and make CH3Cl and water instead of CH3OH2+ and Cl-?

    • @DrBob-fp6gp
      @DrBob-fp6gp 2 года назад

      Great question. Under higher concentrations of HCl, it might dehydrate and do a substitution as you describe. This reaction is an example of an initial acid/base reaction, and we did not explore possible subsequent reactions.

  • @salmanabedi8749
    @salmanabedi8749 2 года назад

    thank u

  • @christinebatain9664
    @christinebatain9664 2 года назад

    Thank you so much Sir. God bless you!

  • @ghostrider1527
    @ghostrider1527 2 года назад

    thank you sir amazing teaching!!!!!!!!!!!

  • @LetsGoPirates22
    @LetsGoPirates22 2 года назад

    ty dr bob that helped a lot, im happy the dogs were excited about ochem I can be now too cause it makes sense