Name: chemical formula mass and percent composition
Uploaded: 2020-09-03T13:38:26.000Z
Duration: 2 min 56 s
Channel: JoVE

K12 Standards

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NC K-12 Science Standard Course of Study

9-12

Chemistry

Matter and its Interactions

PS.Chm.3.3

formula-mass-and-mole-concepts-of-compounds

Formula Mass and Mole Concepts of Compounds

Bir bileşiğin en küçük temsili birimi, bir kimyasal formülle gösterilen moleküldür Kimyasal formüldeki tüm atomların atomik kütleleri, toplanırsa, bileşiğin atomik kütle birimi cinsinden ölçülen moleküler kütlesini verir. Örneğin, sakkaroz veya sofra şekerinin moleküler kütlesini bulmak için, her bir elementin atomik kütlesi, karşılık gelen elementin atom sayısı ile çarpılır. Toplam, sakkarozun moleküler kütlesini verir.Bir mol kimyasal bileşikte bulunan tüm moleküllerin kütlesine, mol başına gram olarak ölçülen molar kütlesi denir. Bir bileşiğin molar kütlesi sayısal olarak moleküler kütlesine eşittir. Örneğin, moleküler kütlesi 342, 3 atomik kütle birimine sahip sakkaroz, mol başına 342, 3 gramlık bir molar kütleye sahip olacaktır.Kimyasal bir maddede bulunan gerçek molekül veya parçacık sayısını bilmek, bileşimini, etkileşimlerini ve kombinasyonlarını anlamak için çok önemlidir. Bununla birlikte, bir bileşiğin belirli bir örneğinde, gerçek molekül sayısını sıradan yollarla saymak pratik değildir. Molar kütle, mol ve Avogadro sayısı arasındaki ilişkiyi kullanarak, mevcut toplam moleküller hesaplanabilir.Konsepte göre, bir bileşiğin molar kütlesi, 6.022 x 10^23 parçacığı oluşturan bileşiğin bir molüne eşdeğerdir. Bu nedenle, 342, 3 gram sakkaroz, 6.022 x 10^23 sakkaroz molekülü içerir. Bununla birlikte, örneğin bir sakkaroz numunesi 150 gram ağırlığındaysa, molekül sayısı bir çapraz çarpım yöntemi kullanılarak hesaplanabilir.Sonuç olarak, 150 gram sakkarozun 2, 63 x 10^23 sakkaroz molekülünden oluştuğu görülmektedir. Bir bileşikteki her bir elementin yüzdesi, bir kütle-yüzde değeri kullanılarak ifade edilebilir. Hesaplamak için, bileşiğin bir molündeki elementin kütlesi, bileşiğin bir molünün toplam kütlesine bölünür ve bir yüzdeye dönüştürülür.Pratikte, sakkarozdaki hidrojenin kütle yüzdesini hesaplamak için, hidrojen atomlarının toplam kütlesi ve sakkaroz moleküllerinin toplam kütlesi formüle dahil edilir. Hesaplanan değer, sakkarozun kütle olarak yüzde 6, 4 hidrojen içerdiğini göstermektedir.

bileşiklerin formül kütlesi ve mol kavramları

<h4>Kovalent Bileşiklerin Formül Kütlesi</h4>
 
 Kimyasal formüller, maddelerin temel bileşimini temsil eder. Kovalent bileşikler için formül, maddenin tek bir molekülünü oluşturan atomların sayılarını ve türlerini temsil eder; bu nedenle, formül kütlesi doğru bir şekilde moleküler kütle olarak adlandırılabilir. Kovalent bir bileşik olan kloroformun moleküler formülü (CHCl3), tek bir molekülün bir karbon atomu, bir hidrojen atomu ve üç klor atomu içerdiğini gösterir. Bir kloroform molekülünün ortalama moleküler kütlesi, bu atomların ortalama atom kütlelerinin toplamına eşittir:
 Kimyasal formüller, maddelerin temel bileşimini temsil eder. Kovalent bileşikler için formül, maddenin tek bir molekülünü oluşturan atomların sayılarını ve türlerini temsil eder; bu nedenle, formül kütlesi doğru bir şekilde moleküler kütle olarak adlandırılabilir. Kovalent bir bileşik olan kloroformun moleküler formülü (CHCl3), tek bir molekülün bir karbon atomu, bir hidrojen atomu ve üç klor atomu içerdiğini gösterir. Bir kloroform molekülünün ortalama moleküler kütlesi, bu atomların ortalama atom kütlelerinin toplamına eşittir:
 
 <img alt=""Eq1"" src=""https://www.jovecore.com/CDNSource/lessons/1017/1017_Equations-01.png"" style=""height: 40px;"" />
 
 <h4>İyonik Bileşiklerin Formül Kütlesi</h4>
 
 İyonik bileşikler, elektriksel olarak nötr olan katı maddeler elde etmek üzere belli oranlarda birleştirilen ayrık katyonlardan ve anyonlardan oluşur. İyonik bir bileşik için formül kütlesi, kovalent bileşikler için formül kütlesi ile aynı şekilde hesaplanır: bileşiğin formülündeki tüm atomların ortalama atom kütlelerini toplayarak. Bununla birlikte, iyonik bir bileşik için formül, ayrı bir molekülün bileşimini temsil etmez, bu nedenle doğru bir şekilde "moleküler kütle" olarak adlandırılamaz.
 
 Örneğin, bildiğimiz sofra tuzu veya sodyum klorür (NaCl), 1:1 oranında birleştirilen sodyum katyonlarından (Na+) ve klorür anyonlarından (Cl−) oluşan iyonik bir bileşiktir. Bu bileşik için formül kütlesi, bileşikteki elementlerin ortalama atomik kütlelerinin eklenmesiyle hesaplanır:
 
 <img alt=""Eq2"" src=""https://www.jovecore.com/CDNSource/lessons/1017/1017_Equations-02.png"" style=""height: 40px;"" />
 
 Bir iyonik bileşiğin formül kütlesini hesaplarken, sodyum katyonları ve klorür anyonları için kütleler yerine ortalama nötr sodyum ve klor atomları kütleleri kullanılmıştır. Bir sodyum katyonu bir sodyum atomundan biraz daha küçük bir kütleye sahip olsa da (bir elektron eksik olduğu için), bu fark bir klorür anyonunun bir klor atomundan biraz daha ağır olması (ekstra elektron nedeniyle) ile dengelenecektir. Dahası, bir elektronun kütlesi, tipik bir atomun kütlesine göre ihmal edilebilir derecede küçüktür.
 
 <h4>Kütle Yüzde Bileşimi</h4>
 
 Bir bileşiğin elemental içeriği kimyasal kimliğini tanımlar ve kimyasal formüller bu elemental içeriği temsil etmenin en özlü yoludur. Bileşikteki her bir elementin kütlesine göre yüzde, o elementin kütle yüzdesi olarak adlandırılır. Yüzde bileşimi, her bir elementin kütlesini bileşiğin toplam kütlesine bölerek hesaplanabilir ve daha sonra bir yüzdeye dönüştürülebilir.
 
 Yüzde bileşimi, bilinen formüllerin farklı bileşiklerinde belirli bir elementin nispi bolluğunu değerlendirme konusunda yararlıdır. Söz konusu bileşiğin moleküler veya ampirik formülü bilindiği sürece, yüzde bileşimi bileşiğin elementlerinin atomik veya molar kütlelerinden türetilebilir.
 
 Örneğin, bir nitrik asit molekülü (HNO3) 14,01 amu ağırlığında bir azot atomu, 1,008 amu ağırlığında bir hidrojen atomu ve üç oksijen atomu (3 × 16,00 amu) = 48,00 amu içerir. Bu nedenle nitrik asidin formül kütlesi ( 14,01 amu + 1,008 amu + 48,00 amu) = 63,02 amu'dur ve yüzde bileşimi:
 
 <img alt=""Eq3"" src=""https://www.jovecore.com/CDNSource/lessons/1017/1017_Equations-03.png"" style=""height: 40px;"" />
 
 <img alt=""Eq4"" src=""https://www.jovecore.com/CDNSource/lessons/1017/1017_Equations-04.png"" style=""height: 40px;"" />
 
 <img alt=""Eq5"" src=""https://www.jovecore.com/CDNSource/lessons/1017/1017_Equations-05.png"" style=""height: 40px;"" />
 
 Bu metin bu kaynaktan uyurlanmıştır: <a href=""https://openstax.org/books/chemistry-2e/pages/3-1-formula-mass-and-the-mole-concept"">Openstax, Chemistry 2e, Section 3.1: Formula Mass and the Mole Concept</a> and <a href=""https://openstax.org/books/chemistry-2e/pages/3-2-determining-empirical-and-molecular-formulas"">Openstax, Chemistry 2e, Section 3.2: Determining Empirical and Molecular Formulas.</a>

Bileşiklerin Formül Kütlesi ve Mol Kavramları

Kovalent Bileşiklerin Formül Kütlesi

Kimyasal formüller, maddelerin temel yapısını temsil eder. Kovalent bileşikler için formül ...

Education

JoVE Core

Kimya

Molecules, Compounds, and Chemical Equations

Moleküller, Bileşikler ve Kimyasal Denklemler

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KEY TERMS AND CONCEPTS

TEMEL TERİMLER VE KAVRAMLAR

chemical formula mass and percent composition

Chemical formula mass and percent composition help describe the makeup of compounds. A chemical formula shows which atoms are present and how many of each atom appear in a substance.

For covalent compounds, the formula shows the atoms in one molecule. That is why formula mass can also be called molecular mass. Chloroform, CHCl3, is one example. Its formula shows one carbon atom, one hydrogen atom, and three chlorine atoms. The molecular mass is the sum of their average atomic masses.

Ionic compounds are different because they contain cations and anions that combine in ratios that make the bulk material electrically neutral. Their formula mass is found the same way, by adding the average atomic masses of the atoms in the formula. Sodium chloride, or table salt, is one example. Its formula, NaCl, shows sodium and chloride in a 1:1 ratio. For ionic compounds, the term molecular mass is not the best choice because the formula does not describe a single molecule.

When calculating formula mass for an ionic compound, neutral atom masses are used instead of ion masses. A sodium cation has slightly less mass than a sodium atom because it has lost an electron. A chloride anion has slightly more mass than a chlorine atom because it has gained an electron. The difference is small, and the mass of an electron is negligibly small compared with the mass of a typical atom.

Percent composition tells how much of a compound’s mass comes from each element. It is found by dividing the mass of each element by the total mass of the compound and converting the result to a percentage. This is useful for comparing the relative amount of an element in compounds with known formulas.

Nitric acid, HNO3, shows how the calculation works. One molecule contains one nitrogen atom with a mass of 14.01 amu, one hydrogen atom with a mass of 1.008 amu, and three oxygen atoms with a total mass of 48.00 amu. Its formula mass is 63.02 amu. From that total, the percent composition of each element can be determined.

Chemical Formula Mass and Percent Composition

chemical-formula-mass-and-percent-composition

molecules and compounds

Atomic Elements, Molecules, and Bonds

Matter is made of elements, and elements are built from atoms. An atom is the smallest unit of an element that still keeps that element’s properties. A silver coin, for example, is made of silver atoms. Each atom keeps the unique properties of silver. Elements are pure substances made of identical atoms. They cannot be broken down into simpler substances by chemical changes. Most elements are atomic elements, which use single atoms as their basic unit. Carbon and sodium are examples of atomic...

molecular models

Molecular Model Types in Chemistry

Molecular models help chemists and students visualize the structures and shapes of atoms and molecules. They represent the molecular architecture of chemical compounds in a way that is easier to study than formulas alone. Skeletal models are simple two-dimensional drawings of compounds. They show the molecular framework, or the bonds, without drawing every atom. In this model, many carbon and hydrogen atoms are not shown directly. Their positions are implied by the ends and junctions of the...

organic compounds

Organic Molecules in Everyday Chemistry

Organic molecules are carbon-based compounds found in living things and in many everyday products. Most organic compounds have carbon as the main element, bonded to hydrogen and other carbon atoms. Some carbon-containing substances, such as carbonates, cyanides, and simple oxides like CO and CO2, are not classified as organic. Carbon can form up to four strong bonds, which helps explain why organic compounds can make chains and rings of many sizes and shapes. These molecules appear in...

formula mass and mole concepts of compounds

Chemical formula mass and percent composition help describe the makeup of compounds. A chemical formula shows which atoms are present and how many of each atom appear in a substance. For covalent compounds, the formula shows the atoms in one molecule. That is why formula mass can also be called molecular mass. Chloroform, CHCl3, is one example. Its formula shows one carbon atom, one hydrogen atom, and three chlorine atoms. The molecular mass is the sum of their average atomic masses. Ionic...

experimental determination of chemical formula

experimental-determination-of-chemical-formula

Finding Empirical and Molecular Formulas

Chemical formulas show the elemental makeup of a compound. When a formula is unknown, scientists often start by measuring the masses of the elements in the sample. Those mass data are then used to find the simplest whole-number ratio of atoms, which gives the empirical formula. To get from mass to atom ratio, the masses of the elements are first converted to moles using molar masses. Chemical formulas describe numbers of atoms, not masses, so this step is necessary. In one example, 1.71 grams...

chemical equations

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Chemical equations show the identities and relative amounts of substances in a chemical reaction. The substances that react are called reactants, and their formulas are written on the left side of the equation. The substances formed are called products, and their formulas are written on the right side. A plus sign (+) separates formulas on the same side, and an arrow (→) shows the change from reactants to products. The numbers in a chemical equation are shown with coefficients. A coefficient...

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Learn how to calculate formula mass for covalent and ionic compounds, then use it to find percent composition with examples like chloroform, salt, and nitric acid.

Chemical Formula Mass and Percent Composition | JoVE K12

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Ohio’s Learning Standards and Model Curriculum

Structure And Properties Of Matter

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Matter and Its Interactions

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CH.3

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New Jersey Student Learning Standards for Science

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CHEM.7.B

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Florida Department of Education

SC.912.P.8

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New York State Science Learning Standards

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The Mole Concept and Avogadro’s Number

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PS.Chm.2.1

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Analyze and interpret data to explain the mechanisms and properties of the two main types of intramolecular (ionic and covalent) bonds.

PS.Chm.3.1

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Construct an explanation to summarize the influences intermolecular forces have on the properties of chemical compounds.

PS.Chm.3.2

Analyze the structure of atoms and isotopes.

Chemical Formula Mass and Percent Composition

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