PDF | Mole as a fundamental unit like meter, liter, second etc. is equally A poor understanding and difficulty in realization of mole concept can. MOLES AND CALCULATIONS USING THE MOLE CONCEPT. INTRODUCTORY TERMS. A. What is an amu? x g. B. We need a conversion to the. Mole definiVon. A mole is the amount of any substance that contains the same number of elementary. enVVes as there are atoms in 12 grams of 12C.

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The Mole Concept. CHAPTER OUTLINE. Determining Formula and Molar Masses. The Mole. Percent Composition. Empirical and Molecular. INTRODUCTION: A mole is a unit which is used to. A mole is a unit which is used to express the amount of substance. It is defined as the amount of substance. describe the terms – mole and molar mass;. • calculate the mass per cent of different elements constituting a compound;. • determine empirical formula and.

The formula mass for this compound is computed as Figure 3.

Table salt, NaCl, contains an array of sodium and chloride ions combined in a ratio. Its formula mass is Note that the average masses of neutral sodium and chlorine atoms were used in this computation, rather than the masses for sodium cations and chlorine anions.

This approach is perfectly acceptable when computing the formula mass of an ionic compound. Even though a sodium cation has a slightly smaller mass than a sodium atom since it is missing an electron , this difference will be offset by the fact that a chloride anion is slightly more massive than a chloride atom due to the extra electron. Moreover, the mass of an electron is negligibly small with respect to the mass of a typical atom.

Even when calculating the mass of an isolated ion, the missing or additional electrons can generally be ignored, since their contribution to the overall mass is negligible, reflected only in the nonsignificant digits that will be lost when the computed mass is properly rounded. The few exceptions to this guideline are very light ions derived from elements with precisely known atomic masses.

Example 2 Computing Formula Mass for an Ionic Compound Aluminum sulfate, Al2 SO4 3, is an ionic compound that is used in the manufacture of paper and in various water purification processes. What is the formula mass amu of this compound?

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For purposes of computing a formula mass, it is helpful to rewrite the formula in the simpler format, Al2S3O Following the approach outlined above, the formula mass for this compound is calculated as follows: Check Your Learning Calcium phosphate, Ca3 PO4 2, is an ionic compound and a common anti-caking agent added to food products.

What is the formula mass amu of calcium phosphate? For example, water, H2O, and hydrogen peroxide, H2O2, are alike in that their respective molecules are composed of hydrogen and oxygen atoms. However, because a hydrogen peroxide molecule contains two oxygen atoms, as opposed to the water molecule, which has only one, the two substances exhibit very different properties.

Today, we possess sophisticated instruments that allow the direct measurement of these defining microscopic traits; however, the same traits were originally derived from the measurement of macroscopic properties the masses and volumes of bulk quantities of matter using relatively simple tools balances and volumetric glassware.

This relationship holds good when reactants are completely converted into products. How many molecules of water are present in 9 gram of water?

In nuclear reactions. The resulting solution was dried and ignited when 1. Show that the above data are in accordance with law of constant composition? The residue is found to weigh 18 gram.

What is the mass of CO2 released in this reaction? In case of isotopes. In another experiment 2. In another experiment.

Mole Concept.pdf - The Mole Concept Model 1 Some selected...

Show that these data are in agreement with the law of multiple proportion. This is a simple ratio. In compoundA The weight of cupric oxide formed was Illustration Two compounds each containing only tin and oxygen had the following composition.

The carbon content in one of these is Show that these results illustrate the law of constant composition. Hence the data illustrate the law of multiple proportion. When gases combined or produced in a chemical reaction. H2O and N2O3 is as given below: N and O reacts with each other N: The stoichiometric coefficients in the chemical equation give the quantitative information of the chemical process.

These coefficients represent the relative number of molecules or moles of the reactants and products. It comes into the picture when reaction involves two ore more reactants.

Mole Concept.pdf

Divide given moles of each reactant by their stoichiometric coefficient. For solving such reactions.

It may also be defined as the reactant that is completely consumed when a reaction goes to completion. Calculation of Limiting Reagent: By calculating the required amount by the equation and comparing it with given amount. By calculating amount of any one product obtained taking each reactant one by one irrespective of other reactants.

The one giving least product is limiting reagent. What is the percentage of CaCO3 in the original mixture? The amount of product that is actually obtained is called the actual yield.

Knowing the actual yield and theoretical yield. How many carbon atoms are present in 0. Calculate the average atomic mass of chlorine A Since the amount of Ar is less than 1 mole, the mass will be less than the mass of 1 mole of Ar, approximately 40 g.

Answer How many copper atoms are in 5. How many Au atoms are in this quantity of gold?

One of these amino acids is glycine, which has the molecular formula C2H5O2N. How many moles of glycine molecules are contained in The recommended daily dietary allowance of vitamin C for children aged 4—8 years is 1. What is the mass of this allowance in grams? Solution As for elements, the mass of a compound can be derived from its molar amount as shown: The molar mass for this compound is computed to be How many carbon atoms are in the same sample?There is still some hydrogen left in the reaction vessel after the reaction.

Andrews, Michael L.

Unformatted text preview:. Sesha Sai Kumar. Computing Formula Mass for an Ionic Compound Aluminum sulfate, Al 2 SO 4 3 , is an ionic compound that is used in the manufacture of paper and in various water purification processes.