Name: sublimation in separation and purification
Uploaded: 2024-04-04T10:51:23.000Z
Duration: 1 min 3 s
Channel: JoVE

K12 Standards

Tennessee Academic Standards

High School

Chemistry

Matter and Its Interactions

CHEM1.PS1.7

Sublimation

Sublimation is the direct phase transformation from the solid to the gaseous phase, bypassing the liquid state.
For example, solid carbon dioxide, or dry ice, sublimes to gaseous carbon dioxide at room temperature and pressure.
This transition occurs at the solid&#8211;gas phase boundary and is not observed above the triple point.
In simple sublimation, the substance is heated in a beaker covered with an upturned watch glass as a secondary surface.
The pure substance is deposited on the watch glass, while impurities are left behind.
Lyophilization, or, freeze-drying is the low-temperature dehydration of heat-sensitive materials with applications in chemistry, biology, and food preservation.
Here, the sample is frozen, and placed in a vacuum. When the temperature is raised, the ice sublimes to water vapor, yielding a cryo-desiccated product.

sublimation

Sublimation is the direct transformation of a solid to a gaseous state. For instance, at standard pressure and room temperature, solid carbon dioxide sublimes to gaseous carbon dioxide. The phase diagram depicts the conditions required for sublimation. This process occurs at the solid-gas phase boundary and is not observed above the triple point of the substance. The reverse of sublimation is called deposition, where a gaseous substance condenses directly into a solid. Sublimation and deposition can both be used to separate an analyte from interferents.
In simple sublimation, a solid sample is heated in a beaker covered with an inverted watch glass acting as the secondary surface. The analyte sublimes into a gas, and then cools to a solid again when it meets the watch glass. For successful purification, the sublimation temperature must be high enough to ensure high vapor pressure, but low enough to avoid either melting or decomposing the substance. Iodine is an example of a substance amenable to purification by simple sublimation.
If the sample is sensitive to heat, low-temperature sublimation techniques such as freeze-drying (also known as lyophilization) can be used. These techniques are often applied to dehydrate the desired material. Here, the sample is frozen using an ultra-low-temperature mixture (dry ice/acetone), and placed in a vessel attached to a vacuum pump. The ice in the sample sublimes to water, leaving behind the desired, cryo-desiccated product. Lyophilization is used extensively in purifying enzymes for use in biochemistry, molecular biology, and food preservation.&#160;

Sublimation is the direct phase transformation from the solid to the gaseous phase, bypassing the liquid state.
For example, solid carbon dioxide, or dry ...

Education

JoVE Core

Analytical Chemistry

Unit 1

Introduction to Separation Methods

KEY TERMS AND CONCEPTS

sublimation in separation and purification

Sublimation is the direct change of a solid into a gas. It skips the liquid state. A common example is solid carbon dioxide, or dry ice, which turns into gaseous carbon dioxide at standard pressure and room temperature.

The phase diagram shows when sublimation can happen. This process occurs at the solid-gas boundary. It is not seen above the triple point of a substance. The reverse process is deposition, which is when a gas changes directly into a solid.

Sublimation and deposition can help separate an analyte from interferents. In simple sublimation, a solid sample is heated in a beaker. The beaker is covered with an inverted watch glass, which acts as the secondary surface. The analyte becomes a gas, then cools and forms a solid again on the watch glass.

For purification to work well, the sublimation temperature must be chosen carefully. It must be high enough to give high vapor pressure. It must also stay low enough to avoid melting or decomposition. Iodine is one substance that can be purified this way.

Heat-sensitive samples can use low-temperature sublimation methods such as freeze-drying, also called lyophilization. These methods are often used to remove water from the desired material. The sample is frozen with an ultra-low-temperature dry ice and acetone mixture. It is then placed in a vessel connected to a vacuum pump. The ice sublimes to water, and the cryo-desiccated product remains.

Lyophilization is widely used to purify enzymes for biochemistry and molecular biology. It is also important in food preservation. These uses make sublimation a useful tool in both chemistry and applied science.

Sublimation in Separation and Purification

sublimation-in-separation-and-purification

states of matter and phase changes

Heating and Cooling During Phase Changes

Heating and cooling can change a substance from one state of matter to another. These phase changes depend on internal energy, which is the total kinetic energy of particles and the potential energy from their interactions. In the condensed phases, stronger intermolecular forces and the pressure on the substance affect that internal energy. The internal energy is highest in the gaseous state, lowest in the solid state, and in between for the liquid state. Phase transitions happen when...

distillation: vapor&ndash;liquid equilibria

Distillation and Boiling Point Changes

Distillation separates a miscible liquid mixture by using differences in boiling points. It works best when the two liquids have a significant boiling point gap, usually at least 20°C. In this process, the mixture is heated until the more volatile component reaches its bubble point and begins to vaporize. The vapor then rises into a condenser. A condenser is a glass tube with separate inner and outer sections. Cold water flows through the outer section and cools the vapor in the inner section,...

filtration

Filtration Setup and Filtrate Collection

Filtration separates a solid from a liquid by passing a suspension through a porous medium. The solid stays on the filter, and the liquid, called the filtrate, passes through. This makes filtration a physical separation process, not a chemical change. The filtering medium is chosen for the purpose of the separation, the amount of material, and the nature of the precipitate. A good filter medium should be inert, mechanically strong, nonabsorbent toward dissolved materials, and able to let...

centrifugation

Centrifugation for Separating Particles

Centrifugation separates particles in a liquid by using differences in size and density. The sample is placed in centrifugation tubes and spun at high angular velocity. This creates centrifugal force, which makes the different components move at different rates. After spinning, the supernatant, or liquid above the settled material, is decanted. In some cases, the pellet is kept for further purification. In other cases, the supernatant is kept and may be spun again for additional processing. <br...

Sublimation is the direct change of a solid into a gas. It skips the liquid state. A common example is solid carbon dioxide, or dry ice, which turns into gaseous carbon dioxide at standard pressure and room temperature. The phase diagram shows when sublimation can happen. This process occurs at the solid-gas boundary. It is not seen above the triple point of a substance. The reverse process is deposition, which is when a gas changes directly into a solid. Sublimation and deposition can help...

recrystallization: solid&ndash;solution equilibria

recrystallization-solidsolution-equilibria

Recrystallization for Purifying Solid Compounds

Recrystallization is a way to purify solid compounds by using differences in solubility. It does not involve a chemical reaction. Instead, it relies on physical properties of the desired compound and the impurities. The process is based on solid-solution equilibrium, also called solubility equilibrium. In this equilibrium, a component is split between the solid phase and the solution phase. At equilibrium, the chemical potential of that component is the same in both phases. To begin...

crystal growth: principles of crystallization

crystal-growth-principles-of-crystallization

Crystal Formation Through Supersaturation

Crystal formation through supersaturation begins when a solution contains more dissolved solute than it can normally hold. In crystallization, atoms or molecules line up into a rigid crystal lattice so the system can lower its energy. To start the process, the solute concentration and the solution temperature must be adjusted so the supersaturation ratio, S, is greater than one. Supersaturation can be increased in two main ways. One method is to concentrate the solution by evaporating the...

precipitation and co-precipitation

Selective Ion Separation by Precipitation

Selective ion separation by precipitation is used to isolate ions from a solution. In qualitative inorganic analysis, ions that form sparingly soluble precipitates with the same reagent can be separated by using differences in their solubility products. A solubility product is the limit at which an ionic solid begins to form from dissolved ions. One example is the separation of Cu(II) and Fe(II) ions as insoluble sulfides. Copper(II) sulfide is first precipitated by adding acidic H2S. The acid...

coagulation

Wastewater Cleanup by Coagulation

Coagulation helps remove colloidal particles from wastewater. Colloids are tiny solid particles suspended in a liquid. They are usually negatively charged, so they attract a compact first layer of positive ions. More counterions gather around them and form an electrical double layer. This charge barrier keeps the particles apart and stabilizes the colloid. These suspended solids can be a problem because they may contain toxins that are hard to remove. Coagulation is used to make the particles...

electrodeposition

Electrodeposition for Metal Ion Separation

Electrodeposition separates metal ions from a solution by using an electric current and an electrolytic cell. The cell has an anode and a cathode. When current flows, oxidation happens at the anode. At the cathode, metal ions gain electrons, undergo reduction, and deposit on the large metal surface. This method works well when metals have very different reduction potentials. Copper and nickel in the same solution can be separated this way. First, the solution is made acidic. Then current is...

extraction: partition and distribution coefficients

extraction-partition-and-distribution-coefficients

Solvent Partitioning in Chemical Extraction

Solvent partitioning in chemical extraction describes how a solute spreads between two immiscible solvents. Immiscible solvents do not mix, such as an aqueous phase and an organic phase. The distribution law, also called Nernst's distribution law or the partition law, explains how that solute is shared at a constant temperature and equilibrium. At equilibrium, the ratio of solute concentrations in the two solvents stays constant. For extraction from water into an organic solvent, this...

extraction: effects of ph

pH Control in Liquid Extraction

pH control in liquid extraction changes how amines and acids move between organic and aqueous phases. The pH of the aqueous phase affects the charge on acidic and basic solutes. The charged form is usually more soluble in the aqueous phase. For a weak base such as an amine, the neutral form is called B. Its partition coefficient, K, describes how the neutral molecule distributes between the two liquids. If the conjugate acid of the amine is soluble only in the aqueous phase, while the base...

extraction: advanced methods

Chelate Extraction for Metal Ion Separation

Chelate extraction is a way to separate metal ions by using an organic ligand, or chelating agent, to form an uncharged metal complex. The chelating agent needs hydrophobic groups, and it must act as a weak acid so it can lose a proton and bind to the metal. Most organic ligands used for this method are not stable in water or are insoluble in the aqueous phase. For that reason, the chelating agent is first placed in the organic phase. It then moves into the aqueous phase, where the...

chromatography: introduction

Chromatography: Separation by Polarity

Chromatography separates compounds by how they divide between a stationary phase and a mobile phase. The stationary phase is the material that holds the compounds for a time. The mobile phase is the solvent that carries the solutes to be analyzed. In column chromatography, a mixture flows through the stationary phase. The compounds separate based on their structure and polarity. Solutes that interact weakly with the stationary phase move faster through the column and exit first. Solutes that...

dialysis

Dialysis Separation by Diffusion

Dialysis separates small molecules from larger ones by diffusion through a semipermeable membrane. It is a purification method used to remove unwanted ions or small organic molecules from a sample while keeping larger analytes in place. The membrane is usually made of cellulose acetate or cellulose nitrate. Its pores are typically about 1 to 5 nm wide. Molecules such as chloride, sodium, and glucose can pass through these pores. Larger molecules, including proteins, hormones, and enzymes, are...

volatilization

Mass Loss in Gravimetric Analysis

Volatilization gravimetry is a way to measure mass loss in a sample by driving off a volatile substance. It helps estimate how much volatile material is present. In this method, a known amount of sample is heated to a high temperature in a crucible or another suitable vessel. As the sample heats, the volatile substance evaporates. The vapor is then completely removed from the crucible, either by continued heating or by bubbling an inert gas through the vessel. The non-volatile part stays...

ion exchange

Ion Exchange Resins and Charged Molecules

Ion exchange chromatography separates charged molecules from a solution by swapping them with mobile, or active, ions on a stationary phase. It is used to separate ions, soften and deionize water, and purify solutions. The method depends on a solid column made of high-molecular-weight, chemically stable polymers that are crosslinked to make them porous and essentially insoluble. These polymers are functionalized with either acidic or basic groups. When acidic groups are present, the resin is a...

key terms and concepts

Learn how sublimation and deposition separate substances, from dry ice and iodine purification to freeze-drying for heat-sensitive samples.

Sublimation in Separation and Purification | JoVE K12

analytical chemistry

JoVE Core Analytical Chemistry simplifies complex chemical principles by breaking them down into clear, engaging animations, making topics from SI Units to NMR spectroscopy more accessible and straightforward. Additionally, the scientist-in-action videos highlight the application of these concepts in real-world research conducted in laboratories globally.

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Formula Mass and Mole Concepts of Compounds

Formula Mass of Covalent Compounds

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Determining the Mass Percent Composition in an Aqueous Solution

Source: Laboratory of Dr. Neal Abrams &#8212; SUNY College of Environmental Science and Forestry
Determining the composition of a solution is an important ...

Solutions and Concentrations

Source: Laboratory of Dr. Michael Evans &#8212; Georgia Institute of Technology
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Reaction Stoichiometry

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Stoichiometry, Product Yield, and Limiting Reactants

Chemical equations represent how a chemical reaction proceeds from reactants to products through physical or chemical change using chemical formulas.
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Understand and be prepared to use values specific to chemical processes: the mole, molar mass, molarity, and percent composition. EXPLANATION: During the early and mid-1800s, a tremendous amount of early research poured into building an understanding of the way that atoms combine. This work required analysis of the percent composition of different substances. Joseph Proust's work with tin oxides led him to publish his law of definite proportions noting that a given pure substance will have a constant ratio for the combination of elements making up the substance. Building on Proust's work, John Dalton published his law of multiple proportions and atomic theory noting that multiple patterns exist for the way that atoms combine, yet the combining atoms are invariable. Meanwhile Amedeo Avogadro hypothesizes that given equal pressures and temperatures, two equal volumes of gas will contain equal numbers of atoms. Acknowledging that the exact number of atoms was unknown in these gaseous volumes, the Latin word "mole" was used. "Mole" translates to "lump" recognizing the ambiguous quantity of gas. A number of attempts have been undertaken historically to quantify the mole. Robert Millikan's oil drop experiment revealed the change of a single electron, which could then be divided into Faraday's Constant for the charge of a mole of electrons. Dividing the charge of a mole of electrons by the charge of a single electron yields the number of electrons in a mole, $6.022\times10^{\wedge}23$. Students should be familiar with how to translate between the given quantities. Student's first use atomism/Dalton's atomic theory in third grade noting that matter is made up of particles too small to be seen. This the first time where students will undertake the process of counting these invisible particles. Electrolysis of water provides a tangible experience to demonstrate the constituent parts of water, though the definite proportions of water may not be easily seen due to the solubility of the gasses produced. The concept of relative mass can be explored by comparing small groups of like items. For example, relative masses of beans can be compared with pinto, white, and black beans. If bags are created with equal numbers of like beans, students can develop a concept of why the smallest bean will have a relative mass of 1, analogous to hydrogen.

CHEM1.PS1.1

Chemical Equations

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

The Atomic Theory of Matter

The earliest recorded discussion of the basic structure of matter comes from ancient Greek philosophers. Leucippus and Democritus argued that all matter ...

Chemical Reactions

A chemical reaction is a process by which the bonds in the atoms of substances are rearranged to generate new substances. Matter cannot be created or ...

Balancing Redox Equations

Electrochemistry is the science involved in the interconversion of electrical and chemical reactions. Such reactions are called reduction-oxidation, or ...

Demonstrate that atoms, and therefore mass, are conserved during a chemical reaction by balancing chemical reactions. EXPLANATION: Standard 7.PS1.4 explores the idea that chemical reactions are rearrangements of atoms, and students undertake the process of balancing chemical reactions with that standard in seventh grade. The introduction of molar masses in high school makes an explicit connection between the number of atoms, as previously investigated, and the actual masses of the atoms, permitting the collection of more concrete evidence for the conservation of mass in chemical reactions.

CHEM1.PS1.2

Reaction Yield

The theoretical yield of a reaction is the amount of product estimated to form based on the stoichiometry of the balanced chemical equation. The ...

A balanced chemical equation provides the information of chemical formulas of the reactants and products involved in the chemical change. A ...

Limiting Reactant

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Chemical Equilibria: Systematic Approach to Equilibrium Calculations

In systems with multiple equilibria, the equilibrium calculations use a systematic approach involving a series of steps to make sure there are as many ...

Perform stoichiometric calculations involving the following relationships: mole- mole; mass-mass; mole-mass; mole- particle; and mass- particle. Show a qualitative understanding of the phenomenon of percent yield, limiting, and excess reagents in a chemical reaction through pictorial and conceptual examples. (states of matter liquid and solid; excluding volume of gasses). EXPLANATION: This standard builds on the idea that balancing chemical reactions provides evidence for conservation of mass and that the behavior of atoms follows predictable patterns. Students now have the opportunity to utilize this understanding as they perform and evaluate chemical reactions. (The concepts of limiting reagent and percent yield are presented; however, students are not expected to determine these values algebraically. Use of molar volume in stoichiometric processes is beyond the scope of this standard.)

CHEM1.PS1.3

Predicting Reaction Outcomes

Kinetics describes the rate and path by which a reaction occurs. In contrast, thermodynamics deals with state functions and describes the properties, ...

Introduction to Chemical Reactions

All chemical reactions begin with a reactant, the general term for one or more substances entering the reaction. Sodium and chloride ions, for example, ...

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 ...

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Types of Chemical Reactions: Exchange and Reversible

An exchange reaction is a chemical reaction in which both synthesis and decomposition occur, chemical bonds are both formed and broken, and chemical ...

Use the reactants in a chemical reaction to predict the products and identify reaction classes (synthesis, decomposition, combustion, single replacement, double replacement). EXPLANATION: Chemical reactions are rearrangements of atoms that follow predicable patterns. There are patterns both at the macroscopic level in the behavior of some of the reaction classes, as well as patterns in the rearrangements of the atoms underlying the reaction. Students should be able to predict the products of the reactions, which also requires the ability to recognize the general patterns for each type of reaction.

CHEM1.PS1.4

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Kinetic Molecular Theory and Gas Laws Explain Properties of Gas Molecules

The test of the kinetic molecular theory (KMT) and its postulates is its ability to explain and describe the behavior of a gas. The various gas laws ...

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Basic Postulates of Kinetic Molecular Theory: Particle Size, Energy, and Collision

The ideal-gas equation, which is empirical, describes the behavior of gases by establishing relationships between their macroscopic properties. For ...

Ideal Gas Law

Derivation of the Ideal Gas Law
Gases are a fundamental state of matter. A gas is a collection of molecules that have a significant distance between their ...

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Gas Laws: Boyle's, Gay-Lussac, Charles', Avogadro's, and Ideal Gas Law

Through experiments, scientists established the mathematical relationships between pairs of variables, such as pressure and temperature, pressure and ...

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Kinetic Molecular Theory: Molecular Velocities, Temperature, and Kinetic Energy

The kinetic molecular theory qualitatively explains the behaviors described by the various gas laws. The postulates of this theory may be applied in a ...

Kinetic Theory of an Ideal Gas

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Applications of the Ideal Gas Law: Molar Mass, Density, and Volume

The volume occupied by one mole of a substance is its molar volume. The ideal gas law, PV = nRT, &nbsp;suggests that the volume of a given quantity of gas ...

Conduct investigations to explore and characterize the behavior of gasses (pressure, volume, and temperature), develop models to represent this behavior, and construct arguments to explain this behavior. Evaluate the relationship (qualitative and quantitatively) at STP between pressure and volume (Boyle's Law), temperature and volume (Charles' Law), temperature and pressure (Gay-Lussac Law) and moles and volume (Avogadro's Law), and evaluate and explain these relationships with respect to kinetic molecular theory. Be able to understand, establish, and predict the relationships between volume, temperature, and pressure using combined gas law both qualitatively and quantitatively. EXPLANATION: When exploring the behavior of gasses, it is important to consider experimental design. Experiments used to show the relationships between these sets of variables should include one independent and one dependent variable. Other variables should be held constant. Pressure should serve as the dependent variable because it cannot be manipulated directly. Avogadro's Law can be used to relate the amount of gas in two different containers in lieu of knowing actual number of gas particles in an individual container. Individual demonstrations can be performed to explore each of the different gas laws.

CHEM1.PS1.5

Ideal Gas Equation

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Source: Laboratory of Dr. Andreas Z&#252;ttel - Swiss Federal Laboratories for Materials Science and Technology
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Chemical Stoichiometry and Gases: Using Ideal Gas Law to Determine Moles

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pV-Diagrams

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CHEM1.PS1.6

Separation of Mixtures via Precipitation

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States of Matter and Phase Changes

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Distillation: Vapor&ndash;Liquid Equilibria

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Filtration

Filtration is the physical separation of solids from a fluid using a filtration medium.
The filtration medium is chosen depending on the purpose of ...

Centrifugation

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...

Recrystallization: Solid&ndash;Solution Equilibria

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Precipitation and Co-precipitation

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Electrodeposition

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Extraction: Effects of pH

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Extraction: Advanced Methods

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Chromatography: Introduction

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Dialysis

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Analyze solutions to identify solutes and solvents, quantitatively analyze concentrations (molarity, percent composition, and ppm), and perform separation methods such as evaporation, distillation, and/or chromatography and show conceptual understanding of distillation. Construct argument to justify the use of certain separation methods under different conditions. EXPLANATION: In seventh grade, students developed an understanding that chemical and physical properties of a sample of matter could be used to identify a substance. Building on this understanding, students now explore the use of these physical and chemical properties to separate mixtures. Analysis of the substances is performed to aid in further discussion and facilitate further quantitative analysis.

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Bronsted-Lowry Acids and Bases

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Lewis Acids and Bases

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Identify acids and bases as a special class of compounds with a specific set of properties. EXPLANATION: The concept of pH is first introduced in seventh grade as a chemical property of matter. Students should be introduced to multiple explanations of acid and base behavior to permit classification of common substances (e.g. baking soda, ammonia, carbon dioxide) as acids or bases. To further develop discussions of solubility, qualitative discussions of the differences between strong and weak acids are appropriate. (Calculations of pH or ion concentrations are beyond the scope of this standard. Discussions of pOH are beyond the scope of this standard. Conjugate pairs are beyond the scope of this standard.)

CHEM1.PS1.8

Sublimation in Separation and Purification

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