Name: reaction rate, arrhenius, and catalysts
Uploaded: 2020-03-26T07:22:26.000Z
Duration: 3 min 17 s
Channel: JoVE

K12 Standards

Louisiana Student Standards for Science

High School

Chemistry

Matter And Its Interactions

HS-PS1-4

Temperature Dependence

המדד למהירות שבה תגובה מתקדמת נקרא קצב התגובה. קצב התגובה הכימית מוגדר על ידי חוק הקצב, המתאר את הקשר בין מהירות התגובה לבין ריכוזי המגיבים. במשוואה זו, k הוא קבוע הקצב, A ו-B הם שני המגיבים, ו-m ו-n הם סדרי התגובה שלהם.
קבוע הקצב ממיר את הקשר ליחידות הקצב הנכונות, שומות לליטר לשנייה. לפיכך, קבוע קצב יש יחידות שונות, בהתאם לסדר הכולל של התגובה. עם זאת, קבוע הקצב הוא בעל משמעות רבה יותר מאשר רק המרת יחידות. קבוע הקצב קשור לכמות האנרגיה המינימלית הדרושה להתרחשות תגובה כימית - הנקראת אנרגיית שפעול.
בתגובה, המגיבים נמצאים במצב התחלתי של אנרגיה פוטנציאלית. ככל שהתגובה מתקדמת, עליה להתגבר על אנרגיה פוטנציאלית מסוימת, אנרגיית ההפעלה, לפני שתגיע למצבה הסופי. האנרגיה נטו של התגובה היא ההבדל בין המצב הראשוני למצב הסופי. הבדל זה יכול להיות שלילי, כלומר התגובה משחררת אנרגיה, או חיובי, כלומר הוא סופג אנרגיה.
אם אין מספיק אנרגיה זמינה כדי להתגבר על אנרגיית ההפעלה, התגובה לא תתקדם. במקרים מסוימים, אנרגיה יכולה להיות מסופקת בצורה של חום. זה מספק אנרגיה נוספת כדי להתגבר על מחסום ההפעלה, ואת התגובה יכולה להמשיך. ניתן להוסיף גם זרז, המספק מסלול חלופי של אנרגיית שפעול נמוכה יותר בין המגיבים לתוצרים.
זרזים אינם נצרכים בתגובה, ולכן, אינם משפיעים על האנרגיה נטו של התגובה. אנרגיית ההפעלה נקבעת באופן ניסויי, והיא קשורה לקבוע התגובה k על ידי משוואת ארניוס כאשר A הוא הגורם הקדם-מעריכי או התדיר, R הוא קבוע הגז האוניברסלי, ו-T היא הטמפרטורה המוחלטת שבה מתרחשת התגובה.
ממשוואה זו אנו יודעים שהגדלת טמפרטורת התגובה או הפחתת אנרגיית ההפעלה מגדילה את קבוע הקצב. אם נחזור למשוואת חוק הקצב, המסקנה היא שקבוע קצב גבוה יותר מביא לקצב תגובה גבוה יותר. זה הגיוני מכיוון שככל שהטמפרטורה עולה, מולקולות נעות מהר יותר ומתנגשות בתדירות גבוהה יותר, וכתוצאה מכך חלק גדול יותר של מולקולות עם אנרגיה גבוהה יותר מאנרגיית ההפעלה.
במעבדה זו, תלמד כיצד למדוד את אנרגיית ההפעלה של תגובה באופן ניסיוני באמצעות פירוק של מי חמצן כתגובת המודל.

תלות בטמפרטורה

קינטיקה כימית 
קצב התגובה הוא המהירות שבה מתרחשת תגובה כימית. קצב התגובה מוגדר כשינוי בריכוז של רכיב בתגובה עם הזמן. מהירות התגובה תלויה במספר גורמים, כולל ריכוז המגיבים והטמפרטורה שבה מבוצעת התגובה. כל מגיב תורם למהירות התגובה על ידי גורם מסוים. קשר זה מוגדר על ידי חוק קצב התגובה.
<h4>חוק התעריפים</h4>
חוק הקצב הוא משוואה המתארת את הקשר בין ריכוז המגיבים, A ו-B, לבין סדרי התגובה שלהם, m ו-n. קבוע הקצב, k, מקשר את הריכוזים והסדר של המגיבים לקצב התגובה. זה תלוי בתגובה כמו הטמפרטורה שבה התגובה מבוצעת.
r = k [A]m[B]n for aA + bB → cC
<h4>משוואת ארניוס</h4>
משוואת ארניוס מקשרת בין קבוע קצב התגובה לאנרגיית ההפעלה של תגובה כימית. אנרגיית השפעול מוגדרת ככמות האנרגיה שתגובה כימית זקוקה לה כדי להתקדם. אם תגובה אינה עומדת בדרישת אנרגיית שפעול זו, התגובה לא תתקדם.
<img src="/CDNSource/lm/labs/51/51_Concepts_2.jpg">
הקשר המעריכי השלילי בין k לטמפרטורה מצביע על כך שככל שהטמפרטורה עולה, גם הערך של k עולה. מכיוון שניתן לקבוע את קבוע הקצב באופן ניסיוני על פני טווח של טמפרטורות, ניתן לחשב את אנרגיית השפעול באמצעות משוואת ארניוס. על ידי לקיחת הלוגריתם הטבעי של שני הצדדים, משוואת ארניוס משוכתבת מחדש כמשוואה ליניארית.
<img src="/CDNSource/lm/labs/51/51_Concepts_3.jpg">
תרשים של ln k לעומת 1/T מניב קו ישר עם שיפוע השווה ל- -Ea/R ויירוט y של ln A. מכיוון שקבוע הגז האידיאלי, R, ידוע, ניתן לקבוע את Ea באופן גרפי באמצעות סדרה של ערכי k בטמפרטורות שונות.
<h4>זרזים ואנרגיית שפעול</h4>
לחלק מהתגובות הכימיות יש אנרגיית שפעול גדולה מספיק שגורמת לתגובה להתקדם לאט, אם בכלל. תגובת הפירוק של מי חמצן לחמצן ומים מתרחשת באופן ספונטני, אך היא מתרחשת בקצב איטי להפליא. אחת הדרכים להתגבר על מחסום ראשוני זה היא לספק אנרגיה בצורה של חום. עם זאת, זה לא תמיד אידיאלי כמו חום מוגזם עלול להשפיע על יציבות המוצרים או מגיבים או עשוי להקל על תגובות לוואי.
אנרגיית ההפעלה של תגובות כימיות ניתנת לשינוי באמצעות זרזים. זרז מוריד את אנרגיית ההפעלה של תגובה כימית, אך הוא אינו נצרך על ידי התגובה. במילים אחרות, זרז מקל על התגובה הכימית בכך שהוא מקל על התגברות על דרישת אנרגיית ההפעלה הקריטית. בפירוק מי חמצן, תוספת של ברזל חנקתי מורידה את אנרגיית ההפעלה ומאפשרת לתגובה להתקדם בקצב מהיר יותר. עם זאת, חשוב לציין כי בעוד זרז עשוי להשפיע על קצב התגובה, זרז אינו משנה את כמות המוצר המיוצר על ידי התגובה.
<h4>הפניות</h4>
<ol>
	<li style="font-size:17px">Kotz, J.C., Treichel Jr, P.M., Townsend, J.R. (2012). כימיה ותגובתיות כימית. בלמונט, קליפורניה: Brooks/Cole, Cengage Learning.</li>
	<li style="font-size:17px">זילברברג, מ. (2009). כימיה: הטבע המולקולרי של חומר ושינוי. בוסטון, מסצ'וסטס: מקגרו היל.</li>
</ol>

קינטיקה כימית 
קצב התגובה הוא המהירות שבה מתרחשת תגובה כימית. קצב התגובה מוגדר כשינוי בריכוז של ...

Education

JoVE Lab Manual

כימיה

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 concentrations of reactants A and B, their reaction orders m and n, and the rate constant k. For a reaction written as aA + bB → cC, the rate law is r = k[A]^m[B]^n. The rate constant depends on the reaction and on the temperature at which it is performed.

The Arrhenius equation links the rate constant to the activation energy of a chemical reaction. Activation energy is the energy a reaction must have to proceed. If a reaction does not reach this energy requirement, it will not continue. The equation also shows that as temperature increases, k increases.

Because the rate constant can be measured at different temperatures, activation energy can be calculated from experimental data. Taking the natural log of both sides of the Arrhenius equation gives a linear form. A plot of ln k versus 1/T produces a straight line with slope -Ea/R and y-intercept ln A. Since R is known, Ea can be found graphically from a series of k values.

Some reactions have such a large activation energy that they are very slow. The decomposition of hydrogen peroxide into oxygen and water happens spontaneously, but at an incredibly slow rate. Heat can help overcome this barrier, but too much heat may affect the stability of the reactants or products or promote side reactions.

Catalysts offer another way to lower activation energy. A catalyst speeds up a reaction by making the energy barrier easier to cross, but it is not consumed. In the decomposition of hydrogen peroxide, iron nitrate lowers the activation energy and increases the reaction rate. A catalyst changes how fast the reaction occurs, but it does not change the amount of product formed.

Reaction Rate, Arrhenius, and Catalysts

lab techniques

Measuring with Accuracy in the Lab

Measuring with accuracy in the lab starts with careful records, the right tools, and correct reading of data. Scientists use lab notebooks to record how an experiment was done. These notes include the amounts of materials used and each step of the procedure. Without that record, an experiment cannot be repeated in the same way. Balances and glassware are used to measure solids and liquids for experiments. The precision of a measurement depends on the equipment used. Digital balances show the...

scientific measurement and lab skills

Graphs, Curve Fit, and Standard Deviation

Two-dimensional graphs help students compare an independent variable with a dependent variable in science data. In a chemistry example, temperature is the independent variable and volume is the dependent variable. After data are collected, the relationship between the two measurements must be quantified so it can be evaluated and compared with other relationships. A graph can also show when no relationship exists between the two variables. To make a two-dimensional graph, each data point needs...

stoichiometry, product yield, and limiting reactants

stoichiometry-product-yield-and-limiting-reactants

Balancing Equations and Reactant Limits

Chemical equations show how reactants change into products during a reaction. Stoichiometry is the study of the relative amounts of reactants and products. It is based on the Law of Conservation of Mass, which says matter is neither created nor destroyed. Because atoms are only rearranged, the number and identity of atoms must match on both sides of a reaction. That is why a chemical equation must be balanced. A balanced equation has the same number of atoms for each element in the reactants...

redox reactions

Oxidation States in Redox Reactions

Oxidation states help identify redox reactions. In a redox reaction, oxidation is the loss of one or more electrons, and reduction is the gain of one or more electrons. These reactions are often tracked by changes in oxidation state, also called oxidation number. Each atom in a molecule has an oxidation state. This number shows how oxidized an atom is compared with its free elemental form. It is written as the charge an atom would have if every bond were purely ionic. In that model, bonding...

ideal gas law

Gas Laws Behind the Ideal Gas Equation

The ideal gas equation brings together the main gas laws used in chemistry. Gases have molecules that are far apart, so their behavior is described with four measurable variables: pressure, volume, number of moles, and temperature. The ideal gas law links these variables with the gas constant, R, which equals 8.314 J·K−1 mol−1. Boyle’s law describes the link between pressure and volume. When temperature and the number of moles stay constant, pressure and volume change in opposite directions.

acid and base concentrations

Acids, Bases, and pH in Titration

Acids, bases, and pH explain how acidic or basic a solution is. An Arrhenius acid releases hydrogen ions when it dissolves in water, while an Arrhenius base releases hydroxide ions. These reactions also create conjugate partners: an acid forms a conjugate base after losing hydrogen, and a base forms a conjugate acid after losing hydroxyl. Every acid has a conjugate base, and every base has a conjugate acid. pH measures the amount of hydrogen ions in a solution. The pH scale runs from 0 to 14...

buffers

Buffer pH and the Common Ion Effect

Buffer solutions help keep pH steady when acids or bases are added. In water, an Arrhenius acid (HA) dissociates into hydrogen ions, H+, and a conjugate base, A-. More hydrogen ions make a solution more acidic and lower its pH. An Arrhenius base (BOH) dissociates into a conjugate acid, B+, and hydroxide ions, OH-. Strong acids and strong bases usually change pH a lot because they react completely in water and raise the amount of H+ or OH-. Buffers reduce those pH changes. A buffer usually...

enthalpy of reaction

Reaction Heat, Hess’s Law, and Calorimetry

Reaction heat is explained through enthalpy, Hess’s law, and calorimetry. These ideas show how heat moves during chemical reactions and how scientists measure it. Thermodynamics is the study of heat energy and other forms of energy, such as work. Its laws are used across science, from biology to physics. The first law says energy is conserved in an isolated system. Energy can change form, such as thermal energy becoming work, but it cannot be created or destroyed. The second law of...

solubility

Solubility in Water and Other Solvents

Solubility describes how much of a solute can dissolve in a specific solvent. It is usually reported as solute mass per solvent volume or as solute mass per solvent mass. For example, sodium chloride has a solubility of 36 g per 100 mL of water at room temperature. If solubility is given by solvent mass, that mass must be converted to volume for later calculations. Temperature changes solubility. Sodium carbonate dissolves at about 7 g per 100 mL of water at 0 °C, 22 g per 100 mL at room...

metal flame emission

Flame Test Metal Color Clues

Flame testing uses a metal sample and a flame to identify a substance by its color. Each element gives off a characteristic light emission in the flame, so the color can help distinguish one element from another. This same idea appears in fireworks, where different metal components create different colors. The color comes from energy absorbed by the metallic component. When a species absorbs energy, that energy can go into translation, vibration, rotation, or electron excitement. Electron...

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

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 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...

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 reaction rate, rate laws, the Arrhenius equation, activation energy, and catalysts explain why chemical reactions speed up with temperature.

Reaction Rate, Arrhenius, and Catalysts | JoVE K12

Minnesota Academic Standards in Science

9-12

3.2.1 9C.3.1.1.2

new-jersey-student-learning-standards-for-science

New Jersey Student Learning Standards for Science

Physical Science

Matter and Its Interactions

HS-PS1-5

Alabama Course of Study Science

Matter and Its Interactions: Energy

9-12.C.3.3.d

Next Generation Science Standards

new-york-state-science-learning-standards

New York State Science Learning Standards

HS. Chemical Reactions

HS-PS1-5.

Georgia Standards of Excellence

SC4.

Collision and Transition State Theory

התכוננו ללמד את תלות בטמפרטורה עם מדריך מדריכים זה באורך 4 דקות. כולל שלבי הכנה מרכזיים עבור מעבדת Chemistry ב-JoVE Lab Manual.

הכנת מדריך עבור תלות בטמפרטורה ב-Chemistry - 1.6K+ צפיות | JoVE Lab Manual

עקבו אחר הנהלים של תלות בטמפרטורה שלב אחר שלב בסרטון פרוטוקול סטודנטים זה באורך 11 דקות. חלק מאוסף Chemistry ב-JoVE Lab Manual.

פרוטוקול סטודנטים עבור תלות בטמפרטורה ב-Chemistry - 4.7K+ צפיות | JoVE Lab Manual

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 ...

Periodic Classification of the Elements

The periodic table arranges atoms based on increasing atomic number so that elements with the same chemical properties recur periodically. When their ...

the-periodic-table-and-organismal-elements

The Periodic Table And Organismal Elements

Atomic Structure

The Greek philosopher Democritus proposed that everything on Earth is made up of tiny particles called atomos, Greek for &#34;indivisible,&#34; from which ...

Electron Configurations

Electron configurations and orbital diagrams can be determined by applying the Aufbau principle (each added electron occupies the subshell of lowest ...

Electronic Structure of Atoms


An atom comprises protons and neutrons, which are contained inside the dense, central&#160;core called the nucleus, with electrons present around the ...

electron-configuration-of-multielectron-atoms

Electron Configuration of Multielectron Atoms

The alkali metal sodium (atomic number 11) has one more electron than the neon atom. This electron must go into the lowest-energy subshell available, the ...

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 ...

The Aufbau Principle and Hund's Rule

To determine the electron configuration for any particular atom, we can build the structures in the order of atomic numbers. Beginning with hydrogen, and ...

Coulomb's Law

Experiments with electric charges have shown that if two objects each have an electric charge, they exert an electric force on each other. The magnitude ...

Electric Charges

From lightning during thunderstorms to electronic devices, the phenomenon of electromagnetism is all around us. The electromagnetic force is one of the ...

sources-and-properties-of-electric-charge

Sources and Properties of Electric Charge

All objects we see around us consist of atoms, which combine to form molecules. The lightest element in the universe is hydrogen, and a hydrogen atom ...

Types of Forces

In most situations, forces can be grouped into two categories: contact forces and field forces.&#160; Contact forces occur as a result of direct physical ...

Electric Fields

Source: Yong P. Chen, PhD, Department of Physics &#38; Astronomy, College of Science, Purdue University, West Lafayette, IN
An electric field is generated ...

Intermolecular Forces

Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions ...

Van der Waals Interactions

Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions ...

Chemical Bonds


Atoms participate in a chemical bond formation&#160;to acquire a completed valence-shell electron configuration similar to that of the noble gas nearest ...

Electron Behavior

Electrons are negatively charged subatomic particles attracted to and orbit around the positively-charged nucleus of an atom. They reside in spaces ...

Subatomic Particles

Dalton was only partially correct about the particles that make up matter. All matter is composed of atoms, and atoms are composed of three smaller ...

Ions and Ionic Charges

In ordinary chemical reactions, the nucleus &mdash; which contains the protons and neutrons of each atom and thus identifies the element &mdash; remains ...

Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level and the composition of the nucleus of atoms.  Clarification Statement: Chemistry: Examples of properties that could be predicted from patterns could include reactivity of metals, types of bonds formed, numbers of bonds formed, atomic radius, atomic mass, or reactions with oxygen. Emphasis is on main group elements and qualitative understanding of the relative trends of ionization energy and electronegativity.

HS-PS1-1

Properties of Transition Metals

Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3&#8211;12 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 ...

Chemical Equations

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

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, ...

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. ...

Stoichiometry, Product Yield, and Limiting Reactants

Source: Smaa Koraym at Johns Hopkins University, MD, USA

	Preparation of 25% v/v Ethylenediamine in Deionized WaterExpand
	Here, we show the laboratory ...

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.  Clarification Statement: Chemistry: Examples of chemical reactions could include the reaction of sodium and chlorine, carbon and oxygen, or carbon and hydrogen. Reaction classification aids in the prediction of products (e.g. synthesis, decomposition, single displacement, double displacement, and acid-base).

HS-PS1-2

Reaction Rate, Arrhenius, and Catalysts

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