Why Do Two Chemical Compounds React
Chemistrystudies changes in matter. A chemicalreaction is a process in which one set of chemical compounds aretransformed into another. Reaction occur when there is an interaction betweenthe compounds in which some initial bonds are broken and some new bonds areformed.
Why does this happen? In simple terms, because the energy holding the new bonds together is higher than the energy that held the initial bonds. This is the definition of a thermodynamically favored process. Favorable thermodynamics is the most fundamental step that leads two compounds to react with each other. Other drastically important factor is reaction kinetics.
What Is The Future Of Chemistry
Chemistryis the science that studies and manipulates matter. We human beings are gettingpretty good at it, , but we arefar from an ideal position in which we can easily make any molecule or compoundat will in a matter of minutes.
That isprobably the future of chemical synthesis, being able to shape any compound atwill in a matter of minutes, without relying on long term challenging synthesis projects. Furthermore, the possibilities ofsynthetic chemistry are literally endless: there will always be room for makinga chemical even better, or finding a molecule that works even better for agiven task.
Another keyaspect of the chemistry of the future will be reaching true fullsustainability. Chemistry will be one of the main branches of science to solvethe problem of energy.
Also,chemistry, as the central science, will be responsible to helping technologyand interdisciplinary science in general to develop smoothly.
Properties Of Hydrogen Iodide
HI is a colorless gas that reacts with oxygen to give water and iodine. With moist air, HI gives a mist of hydroiodic acid. It is exceptionally soluble in water, giving hydroiodic acid. One liter of water will dissolve 425 liters of HI gas, the most concentrated solution having only four water molecules per molecule of HI.
The Other Hydrogen Halides As Ionizing Solvents
The low melting and boiling points of hydrogen chloride, bromide and iodide suggest that little or no association occurs in the liquid phase, quite unlike hydrogen fluoride which is extensively hydrogen bonded. This is further reflected in their low dielectric constants which are, to a first approximation, a good measure of the polarity of the solvent molecules. As might be expected salts have only a limited solubility in these solvents whilst certain covalent compounds, such as the boron, tin and phosphoryl halides and many organic compounds, are quite soluble. Hydrogen chloride has been studied the most extensively and will be discussed briefly hydrogen bromide and hydrogen iodide are very similar in solvent properties to hydrogen chloride but contamination of solutes with iodine formed by disproportionation of hydrogen iodide is often noticed.
As can be seen from Table 6, hydrogen chloride has a narrow liquid range which makes experimentation difficult if vacuum manipulation of the solvent is used the temperature must be closely controlled at about 90°C to prevent an excessive rise in pressure. The conductivity may be explained in terms of the self-ionization
TABLE 6. Physical properties of the hydrogen halides
KEITH J. LAIDLER, in, 1963
What Do You Teach In High School Chemistry
High school chemistry introduces students to more complicated topics such as stoichiometry, thermodynamics, virtual laboratory experiments, and more. This strong base of knowledge will prepare them for subjects such as physics and advanced biology in the near future.
Some other topics that should be covered in tenth grade chemistry include:
- The difference between physical properties and chemical properties of matter.
- The relationship between the number of neutrons in an atom of an element, its mass number, and its isotopes.
- How hydrogen bonding and van der Waals forces affect the volatility, boiling points, and melting points of liquids and solids.
- How kinetic-molecular theory explains the properties of plasmas.
- Spontaneous and nonspontaneous reactions.
- The Bronsted-Lowry definitions of acids and bases.
- The role of nuclear fusion to the production of essentially all elements heavier than helium.
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Primary Standards In The Wet Analysis
Different primary standards are used for the standardization of different substances.
Standardization of silver nitrate
Sodium chloride is used as the primary standard for this purpose. It has a relative molecular weight of 58.44 g/mol. To be exact, 1.4516 g of salt is weighed to form 0.1000 M solution in 250 ml of solution. Salt is added to the volumetric flask and dissolved in a few ml then diluted up to the 250 ml mark. This solution is employed for the standardization of silver nitrate solution.
AgNO3 + NaCl AgCl + NaNO3
Zinc powder is used for standardizing EDTA.
Zn2+ + EDTA4- Zn2-
Standardization of perchloric acid
KPH is used for standardizing the perchloric acid.
KHPhthalate + KOH K2Phthalate + H2O
What Is Hydroiodic Acid
Hydroiodic acid also called Hydriodic acid is a colourless gas, which reddens litmus strongly, and produces dense white fumes in moist air. The chemical formula for hydroiodic acid is HI. Hydroiodic acid is a strong acid made by dissolving hydrogen iodide in water. However both differ in the physical state one is gas and the other is an aqueous solution. It is one of the strongest of all common halide acids due to high stability of its corresponding conjugate base.
Other names Hydrogen iodide, iodane
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Pka And Buffer Capacity
In addition to using pKa to gauge the strength of an acid, it may be used to select buffers. This is possible because of the relationship between pKa and pH:
pH = pKa+ log10
Where the square brackets are used to indicate the concentrations of the acid and its conjugate base.
The equation may be rewritten as:
Ka/ = /
This shows that pKa and pH are equal when half of the acid has dissociated. The buffering capacity of a species or its ability to maintain pH of a solution is highest when the pKa and pH values are close. So, when selecting a buffer, the best choice is the one that has a pKa value close to the target pH of the chemical solution.
What Does Chemistry Mean
As an introduction to chemistry, it is the branch of science that studies matter and change. First, chemistry deals with the study of the composition and the properties of matter . Then, chemistry deals with change, or how these substances evolve when submitted to certain conditions, or how one substance changes or reacts while interacting with a different substance. The definition of chemistry cant be made shorter, since it covers basically everything!
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Gas Phase Ion Energetics Data
Data compilation copyrightby the U.S. Secretary of Commerce on behalf of the U.S.A.All rights reserved.
|gas phase Given: 3.0590463 eV B|
|rH°||gas phase Fe2- «DELTA»S=5.0 B|
|gas phase Given: 3.0590463 eV B|
|rG°||gas phase Fe2- «DELTA»S=5.0 B|
What Is Oxidation And Reduction In Chemistry
Redox processes are a type of chemical reaction inwhich one of the reacting compounds gets oxidized and the other gets reduced. Aredox reaction involves a transfer of electrons. We say that a compound, oratom within a compound, gets oxidized when it loses electrons and the other component gets reduced when it gains electrons.
One of themost typical examples of a redox process is the rusting of iron. Iron metal, Fe0 reacts with oxygen from air, O2 to give rust, or iron oxide, Fe2O3.
4 Fe0 + 3 O2 2 Fe2O3
In this newcompound, the new oxidation state of iron is +3. Iron has lost 3 electrons,therefore, getting oxidized:
Fe0 Fe3+ + 3 e
On theother hand, the new oxidation state of oxygen is -2. Each oxygen atom hasgained two electrons, getting reduced:
O2 + 4 e 2 O2-
A typical exampleof a redox process is an explosion in which the explosive compound gets oxidizedviolently. C4 is a common plastic explosive, much more energetic than dynamite.The main component of C4 is RDX , also known ascyclonite or, according to IUPAC, 1,3,5-trinitro-1,3,5-triazinane.
The processof oxidation of RDX is thermodynamically favorable, and gives rise to aexothermic reaction, in which a large amount of energy is released in the formof heat and light, causing the explosion.
The NNO2 bonds are extremely unstable and prone to oxidation. Thats what makes this kind of compounds highly explosive.
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What Does Hi Stand For Chemistry
We compiled queries of the HI abbreviation in Chemistry in search engines. The most frequently asked HI acronym questions for Chemistry were selected and included on the site.
We thought you asked a similar HI question to the search engine to find the meaning of the HI full form in Chemistry, and we are sure that the following Chemistry HI query list will catch your attention.
What Is Hydroiodic Acid Formula
The hydroiodic acid chemical formula is also called the Hydrogen iodide formula. It is the aqueous solution of hydrogen iodide. When the hydrogen iodide gas is dissolved in water, the Hydroiodic Acid is obtained. In its anhydrous form, it is a molecule that is made up of an iodine atom and a hydrogen atom. The molecular or chemical formula of Hydroiodic Acid is HI.
It is a colourless liquid, having an acrid odour. It is odourless and holds a cooling and saline pungent cooling taste. It can be prepared commercially by reacting iodine with hydrazine that gives nitrogen gas and hydrogen iodide. The hydroiodic acid symbol of the chemical formula hydroiodic acid is Hl.
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What Are Acids And Bases
Following the original definition by Arrhenius, , an acid is a compound that is able to release a hydrogen cation, or proton . For example, molecules of hydrochloric acid get ionized in solution giving a proton to water, through an acid-base equilibrium:
HCl + H2O H3O+ + Cl
HCl in water gives rise to hydronium cations and chloride anions. This is classical acid-base equilibrium.
On the other hand, bases, such as sodium hydroxide , can catch protons from water, giving rise to hydroxide anions.
NaOH +H2O HO + Na+
Whereas the Arrhenius acid-base model is very illustrative, it has its limitations, and other models are used to describe more advanced acid-base theories. The most important ones are the Brønsted-Lowry theory , and the Lewis theory.
Accordingto the Lewis theory, an acid is asubstance that accepts a lone pair of electrons, and a base is a substance thatdonates a lone pair of electrons. This accounts for acid-base equilibria whichcannot be explained by Arrhenius or Brønsted-Lowry theories, such as thebasicity of ammonia in water:
:NH3 + H2O ) NH4+ +:OH
Relative acidity or basicity of solutions or mixtures is measured using a logarithmic scale called the pH scale. It generally goes from 0, most acidic , through pH = 7 , up to 14, most basic . Nevertheless, compounds more basic and acidic than those do exist, pH = 014 is definitely not a closed range. Examples of common solutions or mixtures of different pH are shown in the scale below.
Why Is Chemistry Important
Everythingis chemistry. Everything that you can observe macroscopically is made ofchemicals. You are made of chemicals, your food is chemicals, you breathechemicals, we live out of and thanks to chemicals, everything you see under thesun is a mixture of chemicals.
Everything you see or do is based on chemical concepts and processes. Fireworks going off takes place thanks to our understanding and application of chemistry. A medicine that you take to cure your illness does it so through chemical processes. A building doesnt fall off because we know chemistry. Obviously, all these examples result from a bunch of different branches of science coming together. Chemistry, as the central science, is in charge of gluing them together.
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The Thermal Reactions Of Hydrogen Iodide With Alkyl Iodides1
J. Phys. Chem.
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Note: In lieu of an abstract, this is the article’s first page.
Alkyl Iodides By Hydroiodination Of Alkenes
The reaction of alkenes with hydrogen iodide affords the Markovnikov addition products exclusively. Classically, the HI is generated in situ by treatment of potassium iodide with phosphoric acid < 63OSC543> , but more modern methods of in situ HI generation include combinations of iodine with alumina < 87TL4497, 88JOC4477> and BH3diethylaniline complex with iodine in acetic acid < 90TL1919> . Controlled amounts of water can also generate HI when in the presence of either AlI3< 91CI175> , or TMS-Cl/NaI < 88S366> . Indeed, water is not needed at all if the substrate can donate an acidic proton, as in the example shown in Equation < 83S461> . Markovnikov addition of HI to enones can also be achieved by reaction with tetraethylammonium iodide and trifluoroacetic acid < 83T1529> .
A.K. HOLLIDAY Ph.D., D.Sc., F.R.I.C., A.G. MASSEY B.Sc., Ph.D., A.R.I.C., in, 1965
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What Is Chirality And Where Does It Come From
Chirality is a geometric property of certain molecules. A molecule is said to be chiral when its mirror image is not superimposable to the molecule itself. The classical source of chirality in a compound is the presence of a carbon atom with four different substituents. The concept is far better explained by this basic chemistry youtube video:
The origin of chirality, together with the origin of life is one of the most relevant questions in, not only chemistry, but science in general, so it is not possible to answer in a straightforward manner. The main theory backing it up is based on homochirality, which could have emerged over three steps: mirror-symmetry breaking, chiral amplification and chiral transmission. This is far beyond basic chemistry concepts, but you can further read about it here.
Essential Basic Chemistry Concepts Explained
Learning the basic chemistry concepts, in which an entire chemical education process is based on, can be overwhelming for beginners.
One of the reasons is the vast amount of information that there is out there.
For that reason, I decided to go ahead and explain here 15 important basic chemistry concepts, which hopefully will get you in a better shape for learning chemistry. These are clearly explained in most of the chemistry textbooks in our review.
In case you are starting to learn organic chemistry, we have also published an overview of the most important concepts that you will need, and a further review comparing SN1 and SN2 reactions.
We will start off with an introduction to basic chemistry: background on the most basic definitions of chemistry, a bit of history, and highlighting why and how chemistry is important. The basic units in chemistry will be defined: atoms, molecules, subatomic particles. Then, we will discuss them from a beginner point of view, and formulate them in the format of questions.
Therefore, we aim this article to people that are unfamiliar with chemistry or with science in general. If you are a teacher, you might want to redirect your students here.
Disclaimer: This is not intended to be a comprehensive description of each concept, but rather an introduction to each of them: chemistry basics for beginners. We cite and include sources that we consider useful for expanding them further.
So withoutfurther ado, lets dive in!
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What Is Stoichiometry
Stoichiometry is a very basic chemistry concept. It is just a way of measuring or determining the amount of each substance that is involved in a reaction , and the amount of products that are generated.
Before actually running a reaction in the lab, a chemist needs to figure out what is the number of molecules of each reagent is required for the reaction to proceed. For this purpose, we use a unit called mole. The mole is the base unit of amount of substance. One mole accounts for 6.022·1023 molecules. We need it to be a huge number, since there is a huge number of molecules in each gram of any reagent of a reaction.
Thestoichiometry of a reaction is the measurement of the relative quantities , measured in moles, of thereactants that are involved in the reaction.
For instance, each 2 molecules of hydrogen gas react with 1 molecule of oxygen gas, to generate 2 molecules of water :
2 H2 + 1 O2 2 H2O
So if we were to perform this reaction in a lab, we would have to mix together 2 moles of hydrogen per mole of oxygen. This means using 2 equivalents of hydrogen respect to the amount of oxygen. In this case, while handling gases, the number of moles of each can be controlled by establishing a partial pressure for each of them.
In case of more common solid reagents, we can consider a hypotetical synthesis of sodium carbionate from carbonic acid. We need 2 equivalents of sodium hydride per mole of carbonic acid employed .