Name: air-free solvent transfer by vacuum
Uploaded: 2023-04-30T06:30:46.000Z
Duration: 9 min 41 s
Channel: JoVE

K12 Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

High School

Physical Science

HS. Chemical Reactions

HS-PS1-2.

Schlenk Lines Transfer of Solvents

1. Using Schlenk Lines
1&#160;Start Up
<ol>
	<li>Make sure that all working ports on the manifold are closed, and that all joints are properly greased with high vacuum grease.</li>
	<li>Attach the solvent trap(s) to the vacuum line, and seal by turning on the vacuum pump. NOTE: Each vacuum pump has its own &#8220;unique&#8221; sound when air is actively being pumped out of the system. It is important to &#8220;get to know&#8221; the regular sounds that your vacuum makes while pumping and while under full vacuum.</li>
	<li>Place vacuum-sealed dewars around the solvent trap(s) and fill the dewars with liquid nitrogen (best) or dry ice/acetone slurry (only for low vapor pressure solvents &#8212; risk of vacuum pump damage) to cryogenically protect the vacuum pump.</li>
	<li>Turn on the regulated inert gas flow, and adjust the flow by watching the rate at which the bubbler bubbles. (An approximate flow rate of 5 bubbles per 10 s is ideal)</li>
	<li>Connect desired apparatus to a manifold port using thick rubber tubing or directly using standard taper glassware.</li>
	<li>Clear the headspace (and potentially the apparatus) of residual air and moisture by performing 3 vacuum/inert gas backfill cycles: (1) open the reaction port to vacuum, wait for full vacuum, and then close the reaction port to vacuum; (2) slowly open the reaction port to inert gas, and then wait until the bubbler begins to bubble again. Rapidly opening the port to inert gas may result in air being sucked into the system through the bubbler. Close the reaction port to inert gas. (3) Repeat 3 times total.</li>
</ol>
2 Shut Down
<ol>
	<li>Close off all manifold ports, and turn off the inert gas flow.</li>
	<li>Remove the solvent trap dewar(s). CAUTION: if a blue liquid is present in the trap upon removal, it is possibly liquid oxygen (B.P. -183 &#176;C), which can condense at liquid nitrogen temperatures (B.P. -196 &#176;C) and can form explosive mixtures with organic compounds or cause a rapid pressurization explosion in a closed system upon warming.7 In the case where liquid oxygen is present, immediately replace the dewar in order to keep the trap cold, close the fume hood sash, and inform others of the situation. Leave the trap up and the system under vacuum, and leave it to slowly warm up and evaporate. Condensing liquid oxygen may be avoided by ensuring the manifolds no leaks and by limiting vacuum exposure to ambient atmosphere. A similar event can take place with liquid argon (B. P. -186 &#176;C), and care should be taken to not pump significant volumes of argon through an LN2 trap.</li>
	<li>Turn off vacuum pump and vent the system to ambient atmosphere by opening the solvent trap vent (if applicable) or a port on the main vacuum manifold.</li>
	<li>Remove the solvent traps, and dispose of any trapped volatiles into the appropriate waste container.</li>
</ol>
2. Drying Hydrocarbon Solvents/Reagents
CAUTION: Sodium metal reacts violently with water. Ketyl radicals are dangerously incompatible with some solvents, in particular halogenated solvents. Proper references should be consulted prior to choosing an appropriate desiccant for a given solvent. Follow the guidelines in Purification of Laboratory Chemicals.8-9
1 Preparation of a &#8220;Solvent Pot&#8221; &#8211; 5 g Ph2CO per liter of solvent.10
<ol>
	<li>See Figure 1 for needed glassware. Under inert atmosphere, measure approximately 1 cm5,6 Na metal (wire or chunk), cut it into smaller pieces, and place the pieces into a 500-mL round-bottom flask with a 24/40 standard taper neck joint.</li>
	<li>Weigh approximately 1.25 g of Ph2CO and place it into the 500&#160;mL round bottom flask with the sodium.</li>
	<li>Place a heavy duty stir-bar into the 500&#160;mL round bottom flask, then seal the flask using a 180&#176; 24/40 adapter that has been greased with a minimal amount of heavy duty high vacuum grease. Place a Keck clip over the joint to ensure a sturdy connection.</li>
	<li>Remove the flask from the glovebox and evacuate on the Schlenk/high vacuum line as described in Section 1.2.6. Seal the 180&#176; adapter and remove the flask from the line while it is under vacuum.</li>
	<li>Attach a funnel to the top of the solvent pot (do not use grease!) and fill the funnel with the desired solvent. Using a long needle attached to a nitrogen line, bubble nitrogen through the solvent to partially degas it.</li>
	<li>While maintaining nitrogen bubbling, slowly open the 180&#176; adapter to introduce solvent into the solvent pot. When the solvent level in the funnel approaches the 180&#176; adapter, close the adapter and remove the funnel. &#160;NOTE: Solvent can be introduced in other ways, with varying degrees of air-free rigorousness. Commonly, users may choose to fill the pot while open to air and degas more later, or may choose to fill the pot with pre-dried solvent directly taken from a solvent purification system.</li>
	<li>Stir the solvent pot for several hours, during which time the solution will turn deep purple indicating the formation of the sodium benzophenone ketyl radical. In the case that the pot does not turn deep purple, degas the solution (Section 2.2) and stir again.</li>
</ol>
2 Freeze-pump-thawing to degas solvent
CAUTION: Liquid nitrogen is commonly used to &#8220;freeze&#8221; solvents for freeze-pump-thaw cycles. It is highly recommended not to use liquid nitrogen unless absolutely necessary and upon consultation with supervisors. Cooling a closed system to liquid nitrogen temperatures greatly increases the chance of condensing liquid oxygen if there is a leak in the system. Furthermore, the large temperature gradient increases the chance of glass breaking due to thermal shock. In almost all cases, -78 &#176;C is sufficient to cool a system for degassing with minimal solvent loss.
<ol style="margin-left: 40px;">
	<li>Start up the Schlenk or high vacuum line (Section 1.1) and attach the solvent pot to the manifold (Section 1.1.6).</li>
	<li>Use dry ice/acetone cooling bath to cool down the contents of the pot to -78 &#176;C. This may freeze the solvent depending on its freezing point.&#160; NOTE: A common misconception of &#8220;freeze-pump-thaw&#8221; is that the solvent must be frozen to degas it. This is untrue; in fact it is easier to degas a cold liquid than a frozen solid because gas will get trapped in the solid matrix.</li>
	<li>If the freezing point of the solvent is above -78 &#176;C and the solvent is frozen, open the solvent pot to vacuum by opening the 180&#176; adapter in order to remove the gas headspace in the pot.&#160; Wait for the system to return to full vacuum, and then close the solvent pot to vacuum.</li>
	<li>Allow the solvent pot to return to room temperature, and observe if any bubbles are forming in the solid/liquid mix. If bubbles are present, the solvent is not fully degassed and steps 2.2.2&#8211;2.2.4 should be repeated. Typically three &#8220;freeze-pump-thaw&#8221; cycles are sufficient for degassing.</li>
	<li>If the freezing point of the solvent is below -78 &#176;C and the solvent has a low vapor pressure at -78 &#176;C, then instead of performing steps 2.2.3 and 2.2.4, the solvent pot can be opened to vacuum for approximately 5 min (or until bubbling stops) to degas the system. After 5 minutes, close the 180&#176; adapter. A small amount of solvent may be lost to the vacuum pump trap.</li>
	<li>If the freezing point of the solvent is below -78 &#176;C and the solvent has a higher vapor pressure at -78 &#176;C, two options are available: perform steps 2.2.3 and 2.2.4 and cool with liquid nitrogen instead of the -78 &#176;C bath (less solvent loss, more inherent risk), or perform step 2.2.5 for shorter periods of time (more solvent loss, safer).</li>
</ol>
3. Vacuum transferring solvents/chemicals
<ol>
	<li>Dry a 500-mL receiving Straus flask and a U-shaped vacuum transfer bridge in a drying oven (125 &#176;C) for at least 1 h.</li>
	<li>Attach the Straus flask and solvent pot to the U-shaped bridge and grease all joints lightly with grease. Attach the U-shaped bridge to the vacuum line.&#160; NOTE: This heavy system should be supported by lab jacks and Keck clips to prevent it falling off of the line and breaking. Vacuum from the manifold may not be enough to hold it on the line.</li>
	<li>Evacuate the system as described in step 1.1.6.</li>
	<li>Degas the solvent pot as described in section 2.2.</li>
	<li>Close off the top U-bridge valve to close off the vacuum transfer setup from dynamic vacuum. The system should now be under static vacuum with the Straus valve open and the solvent pot 180&#176; adapter closed.</li>
	<li>Use a lab jack to raise a -78 &#176;C acetone/dry ice to cool the receiving Straus flask.&#160; CAUTION: Cooling a closed system with liquid nitrogen is dangerous, as there is a significant chance of condensing liquid oxygen if there is a leak. While it may be faster to vacuum transfer at liquid nitrogen temperatures, it is not worth the tradeoff in safety. This practice is banned in our laboratories. If a solvent can&#8217;t be vacuum transferred at a -78 &#176;C, it is suggested to use a better vacuum or consider thermal distillation.</li>
	<li>Turn on magnetic stirring to stir the solvent pot, then slowly open the stopcock of the 180&#176; adapter on the solvent pot, so that the liquid in the solvent pot will not rapidly boil over into the U joint.</li>
	<li>Shortly, solvent should begin condensing in the receiving flask. Wait until the solvent pot is almost dried or the desired amount of solvent has been collected. Close the stopcock on the receiving Straus flask and the valve on the solvent pot, which can be refilled or used again.</li>
	<li>If the solvent pot freezes during transfer, close the Straus flask valve and allow the solvent pot to warm to room temperature before continuing.</li>
	<li>If the vacuum transfer is extremely slow or slows down, re-degas the system by following the protocols in section 2.2.</li>
</ol>
4. Testing the collected solvent in a nitrogen glovebox
1 Preparation of the ketyl solution
<ol>
	<li>Weigh out 0.137 g of Ph2CO and more 0.028 g of Na metal in a 20&#160;mL vial.</li>
	<li>Add 20 mL of THF to the vial and a small stirbar, then cap the vial and stir overnight. This should generate a deep purple solution of 0.0337 M Na/Ph2CO ketyl radical with a small excess of Na remaining at the bottom of the vial.&#160;</li>
</ol>
2 Titration of the collected solvent
<ol>
	<li>Pipette approximate 4 mL of the solvent to be tested into a 4&#160;mL vial.</li>
	<li>Use a Pasteur pipette to carefully drop a single drop of purple Na/Ph2CO THF solution in to the vial.</li>
	<li>Gently stir the vial with a clean pipette tip and analyze the resulting color. Solvent that is 10 ppm H2O or less should remain pale purple. (Not blue)</li>
	<li>If the solvent will react with Ph2CO radical (e.g. halogenated solvents such as dichloromethane), test the solvent with Karl Fischer titration or, in the case of deuterated solvents, 1,2,3H NMR spectrometry.&#160;</li>
</ol>

schlenk lines transfer of solvents

Source: Hsin-Chun Chiu and Tyler J. Morin, laboratory of Dr. Ian Tonks&#8212;University of Minnesota Twin Cities
Schlenk lines and high vacuum lines are both used to exclude moisture and oxygen from reactions by running reactions under a slight overpressure of inert gas (usually N2 or Ar) or under vacuum. Vacuum transfer has been developed as a method separate solvents (other volatile reagents) from drying agents (or other nonvolatile agents) and dispense them to reaction or storage vessels while maintaining an air-free environment. Similar to thermal distillations, vacuum transfer separates solvents by vaporizing and condensing them in another receiving vessel; however, vacuum transfers utilize the low pressure in the manifolds of Schlenk and high vacuum lines to lower boiling points to room temperature or below, allowing for cryogenic distillations. This technique can provide a safer alternative to thermal distillation for the collection of air- and moisture-free solvents. After the vacuum transfer, the water content of the collected solvent can be tested quantitatively by Karl Fischer titration, qualitatively by titration with a Na/Ph2CO solution, or by 1H NMR spectroscopy.

The picture was taken of the vacuum transfer in progress (Figure 2) and after the Na/Ph2CO titration titration was performed (Figure 3).
Solvents collected via this method have been tested by ketyl titration. Figure 3 shows the common possible outcomes of the ketyl test. The purple color in (a) indicates &lt; 10 ppm H2O in the solvent; while the blue and colorless solutions indicate a wetter solvent that needs further pur...

Source: Hsin-Chun Chiu and Tyler J. Morin, laboratory of Dr. Ian Tonks&#8212;University of Minnesota Twin Cities
Schlenk lines and high vacuum lines are ...

Certain chemical reactions must be kept free of water and oxygen. A Schlenk line is a dual manifold used in the safe handling of air- and moisture-sensitive reagents.The apparatus was invented in the 1920s by Wilhelm Schlenk. A key component of his design is the Schlenk flask. It has a stopcock, where vacuum or inert gas can be applied to the system, as needed. The neck opening can be interfaced with another apparatus, or sealed with a septum, and reagents can be added without the introduction of air.Once the reagents have been introduced to the apparatus, they can be manipulated in an oxygen- and water-free environment.This video will highlight the basic operation procedures for a Schlenk line, and then demonstrate the principle in the laboratory via the vacuum transfer of solvents.A Schlenk line is a tubular glass apparatus, with one line used to deliver a vacuum, and another line used to deliver inert gas. Together, the system is called a dual manifold. The dual manifold has four to six valved ports, with thick rubber tubing leading to various reaction apparatuses. The inert gas manifold is connected to a pressure regulated inert gas source. It is vented through an oil bubbler to keep the line pressure slightly above atmospheric. The oil bubbler also prevents ambient air from entering the manifold, preventing contamination of the line.The vacuum manifold is connected to a vacuum pump. A cryogenic trap, often cooled with liquid nitrogen or a dry-ice slurry, is located between the vacuum manifold and the pump in order to condense volatile components, thus preventing them from entering and damaging the vacuum pump.A Schlenk line system can be used for many techniques and reactions, such as the vacuum transfer of solvents. This involves the transfer of solvents from vessel to vessel, while maintaining an air free environment.Now that you understand the principles of?Schlenk line operation, lets see a transfer of air- and oxygen-free solvent.To begin, make sure that all working ports on the manifold are closed, and that all joints are properly coated with high vacuum grease.Attach the solvent traps to the vacuum line, and seal them by turning on the vacuum pump.Place vacuum-sealed Dewars around the solvent trap, and fill with liquid nitrogen to cryogenically protect the pump.Turn on the regulated inert gas flow, and adjust by watching the bubbler. Connect the desired apparatus, such as a Schlenk flask, to the manifold port using thick rubber tubing or standard taper glassware.Clear the headspace in the flask by first opening the reaction port to vacuum and fully evacuating the flask. Close the port to vacuum, and then slowly open the reaction port to inert gas and wait until the bubbler begins to bubble again. Close the reaction port to inert gas, and repeat the process two more times.The next step is to prepare a solvent pot. This is used to produce water- and oxygen-free solvent for sensitive reactions. This procedure uses the common benzophenone-sodium setup.To begin, place the glassware and reagents into a glovebox under inert atmosphere. Measure approximately one cubic centimeter of sodium metal, and cut it into smaller pieces. Place the pieces into a 500-mL round-bottomed flask with a standard taper neck joint. Weigh 1.25 g of benzophenone and place it into the round-bottomed flask with the sodium. Add a heavy-duty stir-bar.Seal the flask using a 180? 24/40 adaptor that has been greased with a minimal amount of heavy-duty high vacuum grease. Place a Keck clip over the joint to ensure a secure connection.Remove the flask from the glovebox, and evacuate the flask headspace using the Schlenk line. Seal the 180? adaptor, and remove the flask from the line while under vacuum.Attach a funnel to the top of the solvent pot and fill the funnel with roughly 300 mL of the desired solvent. Using a long needle attached to a nitrogen line, bubble nitrogen through the solvent to partially degas it.While maintaining the nitrogen bubbling, slowly open the 180? adaptor to introduce solvent into the solvent pot. When the solvent level in the funnel approaches the adaptor, close the adaptor and remove the funnel.Stir the pot for several hours. The solution will turn deep purple indicating the formation of the sodium benzophenone ketyl radical. The formation of the radical signifies that the solvent is dry and oxygen-free. If the pot does not turn deep purple, degas the solution. Use the freeze-pump-thaw technique, as described in detail in this collection's "Degassing Liquids with Freeze-Pump-Thaw Cycling."Dry a 500?mL receiving Straus flask and a U-shaped vacuum transfer bridge in a drying oven. A Straus flask is a two-neck round bottom flask. One neck is threaded to allow for the connection of a plug valve.Coat all joints lightly with vacuum grease, and attach the U-shaped bridge to the vacuum line. Connect the Straus flask and solvent pot to the U-shaped bridge. Be sure to secure the heavy system in place using Keck clips. Evacuate the system and degas the solvent as described earlier.Close the top U-bridge valve to close the vacuum. The system should be under static vacuum with the Straus valve open and the solvent pot 180? adapter closed. Use a lab jack to raise a -78 degree acetone/dry ice slurry to cool the receiving Straus flask.Begin stirring the solvent pot, and then slowly open the stopcock of the 180? adaptor. Be sure to turn the stopcock slowly so the liquid will not rapidly boil into the U joint. Solvent will begin condensing in the receiving flask. If the solvent pot freezes during transfer, close the Straus flask valve and allow the solvent pot to warm to room temperature before continuing.If solvent transfer is extremely slow, degas the system again using freeze-pump-thaw.Wait until the solvent pot is almost dry, or until the desired amount of solvent has been collected. Close the stopcock on the receiving flask, and on the solvent pot. The sealed flask can now be removed from the system.To shut down the system, first close off all manifold ports, and turn off the inert gas flow.Next, remove the solvent trap and the Dewars. Take extreme caution if any blue liquid is present in the trap, as it could possibly be liquid oxygen. Consult safety protocols for appropriate action.Schlenk line systems are used in a wide range of air sensitive reactions in organic chemistry.Quantum dots are widely used for single-molecule fluorescence imaging. In this example, quantum dots were synthesized under an inert atmosphere using a Schlenk line. Small cadmium selenide quantum dot cores were first synthesized under inert gas and vacuum conditions. Their fluorescent properties are dictated by the size of the nanoparticle.The selenium was swiftly injected into the cadmium solution to complete the synthesis of the cores. They were then functionalized with mercury and biocompatible polymer coatings, increasing their fluorescent yield. The fluorescence duration of the dots far exceeded that of traditional dyes or proteins.The handling and analysis of volatile and air sensitive gases is typically challenging, but can be safely executed with the use of a Schlenk line. In this example, volatile gases were transferred to a lockable test tube, using a Schlenk line.The test tube was cooled using liquid nitrogen, in order to condense the gases and trap them in the test tube. The contained gases were then transferred to a mass spectrometer using the locked test tube, and a custom connection system.You've just watched JoVE's introduction to the Schlenk line system. You should now understand how to operate a Schlenk line, dry and purify solvents, and conduct a vacuum transfer.Thanks for watching!

Education

JoVE Science Education

Chemistry

Organic Chemistry

air-free solvent transfer by vacuum

Schlenk lines and high vacuum lines are used to move solvents without exposing them to moisture or oxygen. They do this by keeping reactions under a slight overpressure of inert gas, usually nitrogen or argon, or by using vacuum.

Vacuum transfer is a separate method for isolating solvents and other volatile reagents from drying agents or other nonvolatile materials. It lets users dispense clean solvent into a reaction vessel or storage vessel while the air-free environment is maintained. The method works in a way that is similar to thermal distillation, because the solvent is vaporized and then condensed in a second receiving vessel.

A key advantage of vacuum transfer is that the low pressure in Schlenk and high vacuum line manifolds lowers boiling points to room temperature or even below. This makes cryogenic distillations possible. It can also be a safer alternative to thermal distillation when collecting air-free, moisture-free solvents.

After transfer, the collected solvent can be checked for water content. Common tests include Karl Fischer titration, titration with a Na/Ph2CO solution, and 1H NMR spectroscopy.

Air-Free Solvent Transfer by Vacuum

introduction to catalysis

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conducting reactions below room temperature

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Schlenk lines and high vacuum lines are used to move solvents without exposing them to moisture or oxygen. They do this by keeping reactions under a slight overpressure of inert gas, usually nitrogen or argon, or by using vacuum. Vacuum transfer is a separate method for isolating solvents and other volatile reagents from drying agents or other nonvolatile materials. It lets users dispense clean solvent into a reaction vessel or storage vessel while the air-free environment is maintained. The...

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organic chemistry

This collection features techniques routinely used in the organic chemistry lab, focusing on regulating temperature and atmosphere during chemical reactions and post-reaction refinement.

Learn how Schlenk lines and high vacuum lines move solvents under inert gas or vacuum, separate them from drying agents, and support air-free collection.

Air-Free Solvent Transfer by Vacuum | JoVE K12

HS-PS1-5.

Overview

Principles of Schlenk Line Transfer

Schlenk Line Startup

Preparation of a Solvent Pot

Vacuum Transfer of Solvents

Applications

Summary

The Periodic Table

As early chemists discovered more elements, they realized that various elements could be grouped by their similar chemical behaviors. One such grouping ...

Alkali Metals

Group 1 elements are soft and shiny metallic solids. They are malleable, ductile, and good conductors of heat and electricity. The melting points of the ...

Halogens

Group 17 elements, known as halogens, are nonmetals. At room temperature, fluorine and chlorine are gases, bromine is a liquid, and iodine a solid. ...

Noble Gases


The elements in group 18 are noble gases (helium, neon, argon, krypton, xenon, and radon). They earned the name &ldquo;noble&rdquo; because they were ...

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Classifying Matter by Composition

Matter: Pure Substances and Mixtures
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Physical and Chemical Properties of Matter

The characteristics that enable us to distinguish one substance from another are called properties.

Physical Properties of Matter

A physical property is ...

Types of Chemical Bonds

Chemical bonding theories were pioneered by American chemist Gilbert&#xA0;N. Lewis. He developed a model called the Lewis model to explain the type and ...

Lewis Symbols and the Octet Rule

Chemical bonds are complex interactions between two or more atoms or ions, which reduce the potential energy of the molecule. Gilbert N. Lewis developed a ...

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence ...

The Born-Haber Cycle

Lattice Energy&#xA0;

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a ...

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Trends in Lattice Energy: Ion Size and Charge

An ionic compound is stable because of the electrostatic attraction between its positive and negative ions. The lattice energy of a compound is a measure ...

Covalent Bonding and Lewis Structures

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Electronegativity

Whether a bond is nonpolar or polar covalent is determined by a property of the bonding atoms called electronegativity.&#xA0;

Electronegativity values of ...

Ionization Energy

The amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state is called its first ionization energy ...

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Bond Polarity, Dipole Moment, and Percent Ionic Character

Bond Polarity

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Electron Affinity

The electron affinity (EA) is the energy change for adding an electron to a gaseous atom to form an anion (negative ion).



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Lewis Structures of Molecular Compounds and Polyatomic Ions

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Assembly of a Reflux System for Heated Chemical Reactions

Source: Laboratory of Dr. Philip Miller &#8212; Imperial College London
Many chemical experiments require elevated temperatures before any reaction is ...

Resonance

The Lewis structure of a nitrite anion (NO2&minus;) may actually be drawn in two different ways, distinguished by the locations of the N-O and N=O ...

Conducting Reactions Below Room Temperature

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstration by: Matt Smith
When new bonds are formed in the course of a chemical ...

Formal Charges

In some cases, there are seemingly more than one valid Lewis structures for molecules and polyatomic ions. The concept of formal charges can be used to ...

Coordination Chemistry Complexes

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
Transition metals are found everywhere from vitamin ...

Exceptions to the Octet Rule

Many covalent molecules have central atoms that do not have eight electrons in their Lewis structures. These molecules fall into three categories:


	...

determining-rate-laws-and-the-order-of-reaction

Determining Rate Laws and the Order of Reaction

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
All chemical reactions have a specific rate defining the ...

Bond Energies and Bond Lengths

Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, ...

Determining the Empirical Formula

Source: Laboratory of Dr. Neal Abrams - SUNY College of Environmental Science and Forestry
Determining the chemical formula of a compound is at the heart ...

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Dr&#xFC;de called the ...

determining-the-solubility-rules-of-ionic-compounds

Determining the Solubility Rules of Ionic Compounds

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
An ionic compound&#39;s solubility can be determined via ...

atomic-radii-and-effective-nuclear-charge

Atomic Radii and Effective Nuclear Charge

The elements in groups of the periodic table exhibit similar chemical behavior. This similarity occurs because the members of a group have the same number ...

Introduction to Catalysis

Source: Laboratory of Dr. Ryan Richards &#8212; Colorado School of Mines
Catalysis is among the most important fields of modern technology and presently ...

Ionic Radii

Ionic radius is the measure used to describe the size of an ion. A cation always has fewer electrons and the same number of protons as the parent atom; it ...

Introduction to Titration

Source: Laboratory of Dr. Yee Nee Tan &#8212; Agency for Science, Technology, and Research
Titration is a common technique used to quantitatively ...

Le Ch&#226;telier's Principle

Source: Laboratory of Dr. Lynne O&#39;Connell &#8212; Boston College
When the conditions of a system at equilibrium are altered, the system responds in ...

Preparing Anhydrous Reagents and Equipment

Source: Laboratory of Dr. Dana Lashley - College of William and Mary
Demonstrated by: Timothy Beck and Lucas Arney
Many reactions in organic chemistry are ...

Proton Exchange Membrane Fuel Cells

Source: Laboratories of Margaret Workman and Kimberly Frye - Depaul University
The United States consumes a large amount of energy &#8211; the current ...

Solutions and Concentrations

Source: Laboratory of Dr. Michael Evans &#8212; Georgia Institute of Technology
A solution is a homogeneous mixture containing some components in small ...

spectrophotometric-determination-of-an-equilibrium-constant

Spectrophotometric Determination of an Equilibrium Constant

Source: Laboratory of Dr. Michael Evans &#8212; Georgia Institute of Technology
The equilibrium constant, K, for a chemical system is the ratio of product ...

using-differential-scanning-calorimetry-to-measure-changes-in-enthalpy

Using Differential Scanning Calorimetry to Measure Changes in Enthalpy

Source: Laboratory of Dr. Terry Tritt &#8212; Clemson University
Differential Scanning Calorimetry (DSC) is a method of thermodynamic analysis based on ...

Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.

Chemical Equations

Chemical equations represent the identities and relative quantities of substances involved in a chemical reaction. The substances undergoing reaction are ...

Chemical Reactions in Aqueous Solutions

Chemical substances interact in many different ways. Certain chemical reactions exhibit common patterns of reactivity. Due to the vast number of chemical ...

Precipitation Reactions

In a precipitation reaction, aqueous solutions of soluble salts react to give an insoluble ionic compound &#x2013; the precipitate. The reaction occurs ...

Oxidation-Reduction Reactions

Oxidation&ndash;Reduction Reactions

Earth&rsquo;s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential ...

Oxidation Numbers

In redox reactions, the transfer of electrons occurs between reacting species. Electron transfer is described by a hypothetical number called the ...

Acids, Bases and Neutralization Reactions

An acid-base reaction is one in which a hydrogen ion, H+, is transferred from one chemical species to another. Such reactions are of central importance to ...

Synthesis and Decomposition Reactions

Synthesis and decomposition are two types of redox reactions. Synthesis means to make something, whereas decomposition means to break something. The ...

Develop a model to illustrate that the release or absorption of energy from a chemical reaction system depends upon the changes in total bond energy.

HS-PS1-4.

Reaction Rate

The rate of reaction is the change in the amount of a reactant or product per unit time. Reaction rates are therefore determined by measuring the time ...

Measuring Reaction Rates

Polarimetry finds application in chemical kinetics to measure the concentration and reaction kinetics of optically active substances during a chemical ...

Concentration and Rate Law

The rate of a reaction is affected by the concentrations of reactants. Rate laws (differential rate laws) or rate equations are mathematical expressions ...

Determining Order of Reaction

Rate laws describe the relationship between the rate of a chemical reaction and the concentration of its reactants. In a rate law, the rate constant k and ...

the-integrated-rate-law-the-dependence-of-concentration-on-time

The Integrated Rate Law: The Dependence of Concentration on Time

While the differential rate law relates the rate and concentrations of reactants, a second form of rate law called the integrated rate law relates ...

Half-life of a Reaction

The half-life of a reaction (t1/2) is the time required for one-half of a given amount of reactant to be consumed. In each succeeding half-life, half of ...

Temperature Dependence on Reaction Rate

The Collision Theory
Atoms, molecules, or ions must collide before they can react with each other. Atoms must be close together to form chemical bonds. ...

Apply scientific principles and evidence to explain how the rate of a physical or chemical change is affected when conditions are varied.

Air-Free Solvent Transfer by Vacuum

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