Name: organic lab glassware and safe handling
Uploaded: 2020-03-26T07:22:27.000Z
Duration: 3 min 8 s
Channel: JoVE

K12 Standards

Texas Essential Knowledge and Skills

High School

Chemistry

CHEM.1

CHEM.1.D

Basic Organic Chemistry Techniques

عادة ما تستخدم الإجراءات المختبرية في الكيمياء العضوية معدات وتقنيات الأواني الزجاجية القياسية. غالبا ما تستخدم قوارير الأكواب و Erlenmeyer للخلط البسيط والاحتفاظ بالمذيبات. تستخدم القوارير ذات القاع المستدير ذات العنق القصير أو الطويل للتفاعلات تحت الحرارة العالية أو الفراغ. وذلك لأن الشكل الدائري أكثر مقاومة للتشقق في ظل هذه الظروف. 
تفاعلات التسخين هي إجراء معملي شائع. ومع ذلك ، لا يستخدم موقد بنسن بشكل عام للمركبات العضوية لأنها قابلة للاشتعال. عند تسخين تفاعل في دورق أو قارورة إرلينماير ، عادة ما يتم استخدام صفيحة ساخنة مع محرك مغناطيسي. عند تسخين تفاعل في قارورة مستديرة القاع ، يتم استخدام حمام مائي أو عباءة تدفئة لاستيعاب شكل القارورة. 
يجب تسخين العديد من التفاعلات إلى درجة حرارة معينة لفترة زمنية محددة للمضي قدما. يتم إجراء هذه التفاعلات تحت الارتجاع. يستخدم إعداد الارتجاع قارورة مستديرة القاع تحتوي على مذيب تتداخل درجة غليانه مع درجة الحرارة المثلى للتفاعل. يتم تركيب مكثف على القارورة ، ويدخل الماء البارد في الذراع السفلي ويخرج من الذراع العلوي. عندما يتم تسخين الخليط وتقليبه ، يتبخر المذيب ثم يتكثف مرة أخرى في القارورة ، مما يحافظ على حجم التفاعل. 
تقنية شائعة أخرى تستخدم في مختبر الكيمياء العضوية هي الترشيح ، وهي طريقة لفصل المواد الصلبة عن السوائل. الترشيح بالجاذبية هو أبسط تقنية ترشيح تستخدم لفصل المواد الصلبة الحبيبية غير القابلة للذوبان. يتكون هذا الإعداد من قارورة Erlenmeyer وقمع مخروطي الشكل وقطعة مطوية من ورق الترشيح. يسكب الخليط في القمع ، ويمر السائل إلى القارورة ، والتي تسمى المرشح. تبقى المواد الصلبة على ورق الترشيح. 
تقنية الترشيح الأسرع هي الترشيح الفراغي. هنا ، يتم توصيل قمع Büchner بقارورة مرشح باستخدام محول مطاطي. تبدو قارورة المرشح مثل قارورة Erlenmeyer ، ولكن لها ذراع جانبي يربط القارورة بالمكنسة الكهربائية عبر أنابيب مفرغة من الهواء. بعد ذلك ، يتم وضع قطعة مسطحة من ورق الترشيح داخل القمع وتبللها قليلا قبل تشغيل المكنسة الكهربائية ببطء. يتم امتصاص السائل من خلال ورق الترشيح في القارورة ، بينما يتم الاحتفاظ بالمادة الصلبة على ورق الترشيح. 
 في هذا المختبر ، ستقوم بإجراء تفاعل بسيط لتكوين حمض البنزويك ، مما يتيح لك ممارسة تقنيات الكيمياء العضوية البسيطة ، مثل وزن المواد الصلبة وقياس الحجم وإجراء الترشيح الفراغي. ستتدرب بعد ذلك على تقنية الانعكاس باستخدام رباعي هيدروفوران.

تقنيات الكيمياء العضوية الأساسية

الأواني الزجاجية في الكيمياء العضوية
هناك قطع قياسية من الأواني الزجاجية تستخدم في مختبر الكيمياء العضوية. عادة ما تستخدم قوارير الأكواب والقوارير في الخلط البسيط أو لحمل المذيبات ولكن لا ينبغي استخدامها لقياس الحجم ، ما لم تكن هناك حاجة إلى حجم تقريبي فقط. يمكن تقسيم الأواني الزجاجية إلى الفئات التالية:
<ol>
	<li style="font-size:17px">الأواني الزجاجية الحجمية - يشمل ذلك الأواني الزجاجية مثل الأسطوانات المتدرجة والماصات الزجاجية الحجمية والقوارير الحجمية. الغرض من هذه العناصر هو قياس أو توزيع حجم دقيق للمادة. تستخدم الأسطوانة المتدرجة بشكل عام لقياس الأحجام في المختبر العضوي. الأسطوانة المتدرجة لها شكل أسطواني طويل مع علامات حجم على الجانب. من الضروري استخدام أصغر أسطوانة متدرجة ممكنة للحجم المطلوب لتقليل الخطأ. على سبيل المثال ، الأسطوانة المتدرجة سعة 25 مل كافية لقياس 20 مل من الكاشف ، ولكن ليس من الدقة قياس حجم أصغر ، مثل 5 مل. ومع ذلك ، لا تستخدم أسطوانة متدرجة سعة 25 مل لقياس 100 مل عن طريق قياس أربعة أحجام سعة 25 مل ؛ من الأفضل استخدام الأسطوانة المتدرجة سعة 100 مل. </li>
	<li style="font-size:17px">احتواء التفاعل - يمكن استخدام هذه القطع المتخصصة لإيواء تفاعل كيميائي عضوي. القوارير المستديرة القاع هي مثال على هذه الأواني الزجاجية. على عكس قوارير Erlenmeyer ، توفر القوارير ذات القاع المستدير مساحة سطح أكبر وبالتالي توفر تدفئة أو تبريدا أكثر اتساقا. تستخدم القوارير المستديرة السفلية لأداء التفاعلات تحت حرارة عالية أو فراغ لأن شكلها الدائري أكثر مقاومة للتشقق. في هذه الفئة توجد أيضا أواني زجاجية متخصصة تعرف باسم المكثفات ، والتي تستخدم لجمع الأبخرة الغازية وتكثيفها مرة أخرى في المرحلة السائلة المراد جمعها. </li>
	<li style="font-size:17px">الترشيح - تستخدم هذه القطع من الأواني الزجاجية بشكل أساسي للمساعدة في عزل الرواسب من خليط التفاعل. لعزل الرواسب الصلبة ، يلزم وجود جهاز ترشيح. يستخدم أبسط إعداد قمعا زجاجيا متصلا بقارورة Erlenmeyer. يوجد داخل القمع قطعة من ورق الترشيح. يسكب خليط التفاعل الذي يحتوي على المادة الصلبة في القمع ، وستسحب الجاذبية السائل لأسفل إلى القارورة ، تاركة وراءها المادة الصلبة. يعرف هذا باسم ترشيح الجاذبية. ومع ذلك ، قد يتطلب هذا الإعداد فترة طويلة من الوقت لتصفية المادة الصلبة. يستبدل إعداد الترشيح الفراغي قارورة Erlenmeyer بقارورة مفرغة بذراع جانبي والقمع الزجاجي بقمع مرشح من البورسلين يعرف باسم قمع Büchner. هذا الذراع الجانبي متصل بمصدر فراغ. كما كان من قبل ، يسكب خليط التفاعل في قمع المرشح ويتم مساعدة الترشيح بقوة من الفراغ. </li>
	<li style="font-size:17px">الفصل - تستخدم هذه القوارير أو القمرات المتخصصة بشكل أساسي لاستخراج الطور السائل السائل ، وهي تقنية تسمح بفصل المنتجات باستخدام مذيبات ذات أقطاب مختلفة أو كارهة للماء. ستشكل هذه السوائل غير القابلة للامتزاج محلولا غير متجانس ينقسم إلى مرحلتين. تحتوي الممرات الفاصلة على صمام يعرف باسم محبس التثبيت في الأسفل ، مما يسمح بفصل المراحل عن طريق سكبها في وعاء جديد. </li>
	<li style="font-size:17px">النقل - تتكون هذه الأواني الزجاجية في الغالب من زجاجات أو قوارير ذات غطاء مقابل. تستخدم هذه الأواني الزجاجية بشكل أساسي لنقل المواد التي يحتمل أن تكون خطرة بأمان. </li>
	<li style="font-size:17px">الاستخدام العام - تتكون هذه الفئة من الأواني الزجاجية مثل الأكواب وقوارير إرلينماير والقضبان الزجاجية وأي قطع متنوعة أخرى. </li>
</ol>
وزن الكواشف العضوية
يمكن أن تأتي الكواشف العضوية بأشكال متعددة ، ومن المهم ممارسة تقنية معملية جيدة عند الحصول على هذه الكواشف لاستخدامها في التجارب. قم دائما بمراجعة MSDS الخاصة بالكاشف لتحديد المخاطر المحتملة عند العمل معه. يجب قياس الكواشف الصلبة باستخدام قوارب الوزن أو ورق الوزن والنوع المناسب من الميزان. 
إذا كان القياس الدقيق مطلوبا، فاستخدم الميزان التحليلي. إذا كان سيتم استخدام كمية كبيرة من الكاشف ، فاستخدم ميزان تحميل علوي. ضع قارب وزن أو ورق وزن على الميزان واضغط على زر "الفارغة". ستعمل ميزة الفارغة على إبطال كتلة ورق الوزن. استخدم دائما الملاعق لنقل الكواشف الصلبة من الإمداد إلى قارب الوزن. لا تقم أبدا بإعادة استخدام نفس الملعقة لكواشف مختلفة لأن ذلك يمكن أن يلوث كواشف المخزون. ولا تعيد الكاشف الزائد إلى زجاجة المخزون أبدا. بدلا من ذلك ، تخلص منه بالطريقة المناسبة حسب التعليمات. 
عند نقل المادة الصلبة إلى الوعاء المناسب ، استخدم قمعا صغيرا لصب المادة الصلبة بالداخل بعناية. إذا بقي أي مادة صلبة ، فاستخدم كمية صغيرة من المذيب لاستخدامها في قارب الوزن وانقلها إلى القارورة. 
يمكن قياس السوائل العضوية باستخدام الأواني الزجاجية الحجمية ، مثل الأسطوانة المتدرجة. احسب حجم السائل باستخدام كثافته ، ثم قم بتفريغ قارورة التفاعل على الميزان. استخدم ماصة أو أسطوانة متدرجة لنقل الحجم مباشرة إلى قارورة التفاعل. اتبع الإرشادات الخاصة بنوع معين من الأواني الزجاجية. لا تقم أبدا بإعادة استخدام نفس قطعة الأواني الزجاجية لكواشف متعددة ولا تقم أبدا بإعادة الكاشف الزائد إلى زجاجات المخزون السائل. بالنسبة للسوائل ، c 
التدفئة التفاعلات العضوية
في بعض الأحيان تكون الحرارة مطلوبة لتمكين حدوث تفاعل كيميائي عضوي. في إعداد المختبر العام ، يتم تطبيق الحرارة بشكل شائع باستخدام موقد بنسن مع لهب غاز مباشر. في مختبرات الكيمياء العضوية ، يمكن أن يخلق اللهب المكشوف من موقد بنسن وضعا خطيرا. الكواشف العضوية ، وخاصة المذيبات ، شديدة الاحتراق وبعضها يشكل أبخرة بسهولة نسبية. لهذا السبب ، لا تستخدم شعلات بنسن في مختبرات الكيمياء العضوية. 
بدلا من ذلك ، يتم استخدام حمامات التدفئة أو ألواح التسخين أو العباءات لتوفير مصدر غير مباشر للحرارة. تستخدم ألواح التسخين المزودة بوظيفة التحريك المغناطيسي لتسخين الأكواب وقوارير Erlenmeyer. تم تصميم عباءات التسخين لتسخين قارورة مستديرة القاع بأحجام متفاوتة بأمان. تستخدم الحمامات المائية عندما لا تحتاج درجة حرارة التفاعل إلى تجاوز 100 درجة مئوية. يتم غمر التفاعل في الأواني الزجاجية في حمام مائي يتم تسخينه بواسطة لوح ساخن. يتم تعديل درجة الحرارة إلى النطاق المناسب. إذا كانت درجة الحرارة المطلوبة يجب أن تتجاوز 100 درجة مئوية وليس 250 درجة مئوية ، فيمكن استخدام عباءة السيليكون. إذا كان يجب أن تتجاوز درجة الحرارة 250 درجة مئوية ، فيمكن استخدام حمام رملي. 
تتطلب العديد من التفاعلات تسخينها إلى درجة حرارة معينة لفترات طويلة من الزمن حتى تستمر. ومع ذلك ، إذا تم تسخين التفاعل لفترة طويلة من الزمن ، فقد يتبخر المذيب ، مما يتسبب في فقدان محلول التفاعل. بدلا من ذلك ، غالبا ما يتم استخدام إعداد الارتجاع ، والذي يستخدم قارورة مستديرة القاع تحتوي على مذيب. تتداخل درجة غليان المذيب مع درجة الحرارة المثلى للتفاعل. يتم تثبيت القارورة ذات القاع المستدير على حامل ، ويتم تركيب مكثف على القارورة. يتدفق الماء البارد عبر المكثف من أسفل الذراع إلى الذراع العلوي بينما يتم تسخين الخليط وتقليبه. عندما يتم تسخين الخليط ، يتبخر المذيب ثم يتكثف مرة أخرى في القارورة ، مما يحافظ على حجم التفاعل.

الأواني الزجاجية في الكيمياء العضوية
هناك قطع قياسية من الأواني الزجاجية تستخدم في مختبر الكيمياء العضوية. أكواب وقوارير إرلينماير ...

Education

JoVE Lab Manual

الكيمياء

organic lab glassware and safe handling

Organic chemistry labs use specific glassware, careful weighing steps, and controlled heating to keep reactions safe and accurate. Beakers and Erlenmeyer flasks are often used for mixing or holding solvents, but they are not meant for measuring volume unless only an approximate amount is needed.

Volumetric glassware is used when a precise volume matters. This group includes graduated cylinders, volumetric pipettes, and volumetric flasks. A graduated cylinder is commonly used in the organic lab because it has volume markings along a long cylinder. It is best to choose the smallest cylinder that can measure the needed amount. For example, a 25-mL graduated cylinder can measure 20 mL, but it is not accurate for a small volume like 5 mL. It is also better to use a 100-mL graduated cylinder for 100 mL than to measure four separate 25-mL portions.

Other glassware is built to hold reactions or help them proceed under specific conditions. Round-bottom flasks provide more surface area than Erlenmeyer flasks and allow more even heating or cooling. They are useful for reactions under high heat or vacuum because their round shape is less likely to crack. Condensers are another important type of glassware. They collect vapor and turn it back into liquid so it can be collected again.

Glassware is also used for filtration, separation, transport, and general lab work. To remove solid precipitates, a simple gravity filtration setup uses a glass funnel, filter paper, and an Erlenmeyer flask. The liquid passes through while the solid stays behind, but the process can take a long time. A vacuum filtration setup is faster and uses a vacuum flask with a side arm, a B&amp;uuml;chner funnel, and a vacuum source. For liquid-liquid phase extractions, separatory funnels are used to split immiscible liquids into two layers. These flasks and funnels separate products by using solvents with different polarities or hydrophobicities. The stopcock at the bottom lets the layers be drained into a new container. Bottles and vials with matching caps are used for safe transport of hazardous material. Beakers, Erlenmeyer flasks, glass rods, and other mixed-purpose items fall into the general use category.

Organic reagents also need careful handling during weighing and transfer. Students should always check the reagent MSDS, or material safety data sheet, for hazards first. Solid reagents are measured on weighing boats or weighing paper with the correct balance. Use an analytical balance for precise mass and a top-loading balance for larger amounts. After placing the weighing boat on the balance, press tare to zero out its mass. Transfer solids with spatulas, but never use the same spatula for different reagents. Do not return extra reagent to the stock bottle. Instead, discard it as instructed. A small funnel can help move the solid into the reaction vessel, and any residue on the boat can be rinsed in with a small amount of the solvent being used.

Liquids are measured with volumetric glassware such as a graduated cylinder. Their volume can be calculated from density, and the reaction flask can be tared on the balance before transfer. A pipet or graduated cylinder is then used to add the liquid directly to the flask. The same piece of glassware should not be reused for multiple reagents, and excess liquid should never go back into the stock bottle. When heat is needed for an organic reaction, a Bunsen burner is avoided because organic solvents and vapors can ignite easily. Instead, labs use hotplates, heating baths, or heating mantles. Hotplates with magnetic stirring heat beakers and Erlenmeyer flasks. Heating mantles are made for round-bottom flasks. Water baths are used when the reaction temperature stays below 100 &amp;deg;C. Silicone mantles are used when the temperature must be above 100 &amp;deg;C but below 250 &amp;deg;C, and sand baths are used above 250 &amp;deg;C. For long heating times, a reflux setup helps prevent solvent loss. A round-bottom flask with solvent is clamped to a stand, a condenser is attached, and cold water flows from the bottom arm to the top arm while the mixture is heated and stirred. The solvent vapor condenses and returns to the flask, which keeps the reaction volume steady.

Organic Lab Glassware and Safe Handling

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balmer series

Hydrogen Emission Lines

Hydrogen emission lines show how electrons move between fixed energy levels in the Bohr model. Niels Bohr proposed this model for the hydrogen atom in 1913. In this model, an electron can only occupy certain orbits, and it cannot exist between them. These energy states are labeled with the quantum number n. The ground state is n = 1. Higher values, such as n = 2, 3, 4, and so on, are excited states. An electron changes state only by absorbing or emitting energy equal to the difference between...

beer's law

Absorbance Spectra and Beer-Lambert Analysis

Absorbance spectra and the Beer-Lambert Law show how light can be used to study molecules in solution. When light hits a substance, it may be absorbed, transmitted, or reflected. A substance often interacts with a range of wavelengths, and each wavelength can affect the molecules or atoms in a different way. When a molecule absorbs light, that energy can be used for translation, vibration, rotation, or electron excitement. Electron excitement is especially important in spectroscopy because it...

concentration dependence

Reaction Order and Rate Constants

Chemical kinetics describes the speed of a chemical reaction. The rate depends on the reaction mechanism, the complexity of the reaction, and the number of reactants involved. Reactant concentration also affects how fast a reaction happens. The rate law is the experimental relationship that connects these factors to reaction rate. In the rate law, each reactant contributes through a reaction order. The general form is r = k[A]^m[B]^n for aA + bB + ... → cC. Here, r is the reaction rate, k is...

temperature dependence

Reaction Rate, Arrhenius, and Catalysts

Chemical kinetics explains how fast a reaction happens and why that speed changes. The reaction rate is the speed of a chemical reaction. It is defined as the change in concentration of a reactant or product over time. Reaction speed depends on several factors, including the concentration of the reactants and the temperature of the reaction. Each reactant affects the rate in a specific way. That relationship is described by the rate law. The rate law is an equation that connects the...

galvanic cells

Battery Power from Redox Reactions

Electrochemistry studies how chemical change and electrical energy are linked. In this branch of chemistry, electrons move from one species to another. That movement can either produce current or be driven by an applied current. The main reaction in electrochemistry is the oxidation-reduction, or redox, reaction. A redox reaction has two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. These changes also shift the oxidation state of each substance. The...

electrolytic cells

Electroplating with Electrolytic Cells

Electrochemistry links electrical energy with chemical change, and electrolytic cells show how electricity can drive a nonspontaneous reaction. In these reactions, electrons move from one species to another. The key chemistry is a redox reaction, or oxidation-reduction reaction, which happens in two half-reactions. Oxidation is the loss of electrons, and reduction is the gain of electrons. The substance that loses electrons is the reducing agent, and the substance that gains electrons is the...

proper lab notebook keeping

Recording a Reproducible Lab Experiment

Accurate lab notebook records are essential in science and organic chemistry labs. Without clear notes, descriptions, quantities, and observations, an experiment cannot be repeated or checked. Good record keeping supports reproducibility, which means other people can follow the same work and get similar results. A laboratory notebook is useful in school labs, research settings, and industry. It can also become a legal record when an idea, process, substance, or technique is patented and...

basic organic chemistry techniques

Organic chemistry labs use specific glassware, careful weighing steps, and controlled heating to keep reactions safe and accurate. Beakers and Erlenmeyer flasks are often used for mixing or holding solvents, but they are not meant for measuring volume unless only an approximate amount is needed. Volumetric glassware is used when a precise volume matters. This group includes graduated cylinders, volumetric pipettes, and volumetric flasks. A graduated cylinder is commonly used in the organic lab...

melting points

How Impurities Change Melting Points

Melting point helps identify an organic compound by showing the temperature where a solid turns into a liquid at 1 atmosphere of pressure. It is a physical property, like solubility, density, color, and electronegativity. Because the exact start of melting is hard to measure, the result is reported as a range. The lower end is when the first drops of liquid appear. The upper end is when the last solid has melted. Scientists compare this range with literature values to help identify a compound. <br...

boiling points

Boiling Point and Vapor Pressure

Boiling point and vapor pressure are key physical properties of a liquid. For a pure compound, the boiling point can help identify the substance. In experiments, the boiling point is usually recorded as a range because exact values are hard to measure and may differ by a few degrees from the literature value. Vapor pressure explains why a liquid boils. In a sealed container, some molecules at the liquid surface gain enough energy to escape into the gas phase. At the same time, some gas...

recrystallization

Purifying Crystals by Solubility

Purifying crystals by solubility is a key organic chemistry technique. Recrystallization uses differences in solubility to separate a desired solid product from starting materials, solvent, and impurities. It is one of the three standard purification methods, along with distillation and extraction. Solubility is the maximum amount of a substance that can dissolve in a fixed volume of solvent at a given temperature. Different solutes dissolve in different solvents, and their behavior can vary...

extraction

Separating Mixtures with Solvent Extraction

Solvent extraction is a common way to separate and isolate a target compound in organic chemistry. In this process, a solute moves from one phase to another so it can be separated from unreacted starting materials or impurities. Extraction is also useful when a product is dissolved in a reaction solvent that is hard to remove by evaporation, such as a solvent with a high boiling point. There are three main types of extraction. In solid-liquid extraction, the solute moves from a solid phase...

simple distillation

Separating Liquids by Boiling Point

Separating liquids by boiling point is the goal of distillation. A miscible mixture contains liquids that mix evenly, and it can be heated so that the more volatile liquid evaporates first. Volatility is a liquid’s tendency to vaporize, and boiling begins when bubbles form in the liquid phase. In a closed container, liquid and vapor can reach equilibrium, which means the rate of vaporization equals the rate of condensation. The pressure from the vapor above the liquid is called vapor pressure.

steam distillation

Steam Distillation and Low-Boiling Separation

Steam distillation is a separation method for temperature-sensitive organic compounds. It works best when the organic compound is immiscible in water, meaning the two liquids do not mix. The method helps remove the organic molecule from a non-volatile contaminant without using the higher temperatures needed for many other separations. In steam distillation, the immiscible mixture is heated until both water and the volatile organic compound distill together. The vapor rises to a condenser,...

thin-layer chromatography

TLC Separation by Polarity

Thin-layer chromatography (TLC) separates compounds in a mixture by polarity. It uses the same basic parts as other chromatography methods: a stationary phase, a mobile phase, and the solute. In TLC, the stationary phase is a thin coating on a plate instead of material packed into a column. The stationary phase in most TLC systems is polar silica gel, a form of silicon dioxide. Its surface has OH groups that can form hydrogen bonds. The sample is first spotted on a pencil start line with a...

column chromatography

Separating Mixtures by Polarity

Column chromatography separates compounds in an organic chemistry lab by using differences in physical properties. It is especially useful for microscale separations when less than 10 grams of material is available for analysis. The method can separate a mixture based on solubility, polarity, hydrophobicity, size, and charge. Any chromatography system has three main parts: the stationary phase, the mobile phase, and the sample mixture. In column chromatography, the stationary phase is usually...

hydrolysis of an ester

Soap Formation from Triglycerides

Triglycerides are lipids made of a glycerol backbone linked to three fatty acids. They are common in vegetable oils and animal fats. Plant lipids are the basis of vegetable oils, while animal lipids are used as lard or general sources of fats. A fatty acid has a long carbon chain, usually between 12 and 20 carbons, with a weak organic acid at one end. Some fatty acids contain double bonds. These are unsaturated fats. The double bond usually gives the chain a bent, cis shape. As a result,...

synthesis of luminol

Luminol Chemiluminescence in Forensics

Luminol chemiluminescence shows how a chemical reaction can produce light and help with blood detection. Chemical reactions may be endothermic or exothermic, depending on whether they absorb or release heat as reactants become products. The enthalpy of a reaction is the energy difference between reactants and products, or ΔH. A positive ΔH means the reaction is endothermic. A negative ΔH means it is exothermic. Many reactions do not happen in a single step. They can pass through intermediates...

esterification

Ester Formation and Everyday Fragrances

Esters are organic compounds with a carbonyl group attached to an oxygen that connects to another alkyl or aryl group. Their general formula is RCOOR'. They are often made by reacting a carboxylic acid with an alcohol in an esterification reaction. In this process, the hydroxyl group of the acid is replaced by an alkyl or aryl group. Many simple esters have familiar fruit and flower smells because their structures are small and less complex. Formic acid and methanol can combine to form methyl...

identification of unknown aldehydes and ketones

identification-of-unknown-aldehydes-and-ketones

Carbonyl Tests for Aldehydes and Ketones

Aldehydes and ketones are carbonyl compounds, which means they contain a C=O functional group. A ketone has two alkyl or aryl groups attached to the carbonyl carbon. Acetone is the simplest ketone, with two methyl groups. An aldehyde is similar, but it has at least one hydrogen attached to the carbonyl carbon. Formaldehyde is the simplest aldehyde, and acetaldehyde has one hydrogen and one methyl group. The carbonyl carbon in both aldehydes and ketones is electrophilic because the oxygen atom...

uv-vis spectroscopy of dyes

How Dyes Absorb Visible Light

Dyes absorb visible light because their molecular structure lets them interact with specific wavelengths. When light hits a substance, some light is absorbed and the rest is reflected or transmitted. The color we see depends on the wavelength that is reflected. A blue substance reflects blue light, around 430 to 480 nm, and absorbs the complementary orange region, around 590 to 630 nm. Compounds that do not absorb in the visible range appear colorless to the human eye. Light also has energy and...

identifying alcohols

Alcohol Tests for Primary, Secondary, and Tertiary

Alcohol tests can help sort alcohols by structure and reactivity. Alcohols are organic molecules with a hydroxyl group attached to an alkyl or aryl group, written as ROH. If the carbon with the hydroxyl group has one R group, the alcohol is primary. If it has two R groups, it is secondary. If it has three R groups, it is tertiary. Alcohols can also be aromatic when they contain a benzene ring. Phenol is the simplest aromatic alcohol. To identify an alcohol, chemists can use its chemical...

chemistry

Comprehensive, curriculum-focused videos for both instructors and students in introductory chemistry lab courses.

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Learn how high school organic chemistry labs use glassware, filtration, separatory funnels, weighing tools, and safe heating methods for reactions.

Organic Lab Glassware and Safe Handling | JoVE K12

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Scientific Laws and Theories

Scientific Laws

In science, a law is defined as a concise, verbal or mathematical, statement that summarizes a vast number of experimental observations. ...

The Scientific Method

Chemistry is an empirical science. Scientists often pose questions to understand the chemistry in everyday life and seek answers to these questions. To ...

CHEM.1.A

What is an Experiment?

An experiment is a planned activity carried out under controlled conditions. The purpose of an experiment is to investigate the relationship between two ...

Study Design in Statistics

A study design is a set of techniques that allow a researcher to collect and analyze data from different variables defined for a specific research ...

Observational Studies

Observational studies are a type of analytical study where researchers observe events without any interventions. In other words, the researcher does not ...

Experimental Designs

An experimental design is a systematic process that allows researchers to evaluate the relationship between dependent and independent variables. There are ...

Randomized Experiments

The randomization process involves assigning study participants randomly to experimental or control groups based on their probability of being equally ...

Crossover Experiments

Crossover experiments, also called the repeated-measurements design, is a study design in which all experimental units are exposed to all treatments in ...

Controls in Experiments

When conducting an experiment, it is crucial to have control to reduce bias and accurately measure the dependent variables. It also marks the results more ...

Bias

Bias refers to any tendency that prevents a question from being considered unprejudiced. In research, bias occurs when one outcome or answer is selected ...

Blinding

Blinding is a commonly used method of not telling participants which treatment a subject is receiving. Blinding is a critical part of a randomized control ...

CHEM.1.B

Proper Personal Protective Equipment

Robert M. Rioux &#38; William A Elliott, Pennsylvania State University, University Park, PA
Hazards are many and varied in the laboratory, but the right ...

Emergency Eyewash and Shower Stations

Robert M. Rioux, Pennsylvania State University, University Park, PA
The Occupational Safety and Health Administration (OSHA) mandates that an emergency ...

Electrical Safety

Robert M. Rioux &amp; Suprita Jharimune, Pennsylvania State University, University Park, PA
Among the many hazards present in the laboratory, electrical ...

Working with Centrifuges

Source: Robert M. Rioux &amp; Suprita Jharimune, Pennsylvania State University, University Park, PA
Earth's gravitational force is capable of separating ...

Working with Hot and Cold Sources

Source: Robert M. Rioux &amp; Suprita Jharimune, Pennsylvania State University, University Park, PA
Working with extreme temperatures, both high and low, ...

guidelines-in-case-of-a-laboratory-emergency

Guidelines in Case of a Laboratory Emergency

Robert M. Rioux &amp; Zhifeng Chen, Pennsylvania State University, University Park, PA
The most common laboratory emergencies include chemical spills, ...

chemical-storage-categories-hazards-and-compatibilities

Chemical Storage: Categories, Hazards And Compatibilities

Source: Robert M. Rioux &amp; Taslima A. Zaman, Pennsylvania State University, University Park, PA
While the use of various chemicals in experimental ...

Safe Handling of Mineral Acids

Source: Robert M. Rioux &#38; Taslima A. Zaman, Pennsylvania State University, University Park, PA
A mineral acid (or inorganic acid) is defined as a ...

Handling Chemical Spills

Source: Robert M. Rioux &#38; Taslima Zaman, Pennsylvania State University, University Park, PA
Since chemicals are commonly used for laboratory research ...

Proper Use of Autoclaves

Robert M. Rioux &amp; Zhifeng Chen, Pennsylvania State University, University Park, PA
Autoclaving is one of the most commonly used methods in the ...

Fume Hoods and Laminar Flow Cabinets

Robert M. Rioux &amp; William A. Elliott, Pennsylvania State University, University Park, PA
Fume hoods and laminar flow cabinets are engineering controls ...

handling-air-and-water-sensitive-chemicals-using-a-schlenk-line

Handling Air- and Water-Sensitive Chemicals Using a Schlenk Line

Robert M Rioux, Ajay Sathe, Zhifeng Chen, Pennsylvania State University, University Park, PA
The use of reagents sensitive to oxidation or moisture ...

proper-operation-of-vacuum-based-equipment

Proper Operation of Vacuum Based Equipment

Source: Robert M. Rioux, Ajay Sathe &#38; Zhifeng Chen, Pennsylvania State University, University Park, PA
Vacuum is required for a number of laboratory ...

Operating the Glovebox

Robert M Rioux, Ajay Sathe, Zhifeng Chen, Pennsylvania State University, University Park, PA 
A glovebox is an isolated enclosure that is designed to ...

operation-of-high-pressure-reactor-vessels

Operation of High-pressure Reactor Vessels

Robert M Rioux, Pennsylvania State University, University Park, PA
The use of gases in a synthetic chemistry laboratory is essential for carrying out a ...

CHEM.1.C

Lab Techniques

Measurement Accuracy
The ability to repeat an experiment and get the same results, or reproducibility, is essential in scientific research. However, ...

Scientific Measurement and Lab Skills

Two-Dimensional Graphs
Some chemistry experiments take the form of directly changing one property of the system that you are studying otherwise known as ...

Proper Lab Notebook Keeping

Organic Lab Notebook Keeping
Record keeping is a vital skill in science and organic chemistry labs. Without proper notes, descriptions, quantities, or ...

Glassware in Organic Chemistry
There are standard pieces of glassware that are used in the organic chemistry lab. Beakers and Erlenmeyer flasks are ...

Measurement: Standard Units

Every measurement provides three kinds of information: the size or magnitude of the measurement (a number), a standard of comparison for the measurement ...

Measurement: Derived Units

The International System of Units or SI system, by international agreement, has fixed measurement units for seven fundamental properties: length, mass, ...

uncertainty-in-measurement-accuracy-and-precision

Uncertainty in Measurement: Accuracy and Precision

Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy ...

uncertainty-in-measurement-reading-instruments

Uncertainty in Measurement: Reading Instruments

Counting is the type of measurement that is free from uncertainty, provided the number of objects being counted does not change during the process. Such ...

uncertainty-in-measurement-significant-figures

Uncertainty in Measurement: Significant Figures

All the digits in a measurement, including the uncertain last digit, are called significant figures or significant digits. Note that zero may be a ...

CHEM.1.E

Scientific and engineering practices. The student, for at least 40% of instructional time, asks questions, identifies problems, and plans and safely conducts classroom, laboratory, and field investigations to answer questions, explain phenomena, or design solutions using appropriate tools and models. The student is expected to:

Organic Lab Glassware and Safe Handling

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