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, , Name of student:, , Brother’s Academy, , Brother’s Chemistry, Standard: XI (FYJC), Section: I, Physical & Inorganic Chemistry, Chapter No. 02, Introduction to Analytical Chemistry, Maximum Marks: 04, Marks with option: 06, , Prof. Umar P. Pinjari, M.Sc. (Org. Chem.). SET., , , Contents:⇨, Chemical reactions and, , I, , Introduction, , V, stoichiometric calculations, , II, , Analysis, , VI, , Limiting reagents, , Mathematical operations and, III, , VII Concentration of solutions, error analysis, Determination of molecular, , IV, , VIII Use of graph in analysis, formula

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02. Introduction to Analytical Chemistry, I), , , Std: XI, , Introduction:⇨, , Analytical chemistry: - The branch of chemistry which deals with the study of separation,, identification, quantitative & qualitative determination of compositions of different substances is, called analytical chemistry. Analysis may be qualitative or quantitative., , 1), , Qualitative analysis is concerned with the detection of the presence or absence of elements in compounds, & of chemical compounds in mixtures., , 2), , Quantitative analysis deals with the determination of relative proportion of elements in compounds and, of chemical compounds in mixtures., , , i), , Importance & scope of analytical chemistry:, , Chemical analysis is one of the most important methods to monitoring the composition of raw materials,, intermediates & finished products & also the composition of air in streets & premises of industrial plants., , ii), , In agriculture, chemical analysis is used to determine the composition of soils & fertilizers., , iii), , In medicines, it is used to determine the composition of medicinal preparations., , iv), , Analytical chemistry has applications in forensic science, engineering & industry., , v), , Industrial process as a whole and the production of little kind of materials are closely associated with, analytical chemistry., , II), , Analysis:⇨, , Analysis is carried out on a small sample of the material to be tested and not on the entire bulk., When the amount of a solid or liquid sample is a few grams the analysis is called semi-microanalysis. It, is two types: qualitative and quantitative., Classical qualitative analysis methods include separations such as precipitation, extraction and, distillation. Identification may be based on differences in colour, odour, melting point, boiling point, and reactivity., Classical quantitative methods consist of volumetric analysis (Titrimetric analysis), gravimetric, (decomposition, precipitation) analysis, etc., , Classical methods of qualitative analysis: ⇒, , Chemical analysis of a sample is carried out mainly in two stages:, (a) By the dry method, , (b) By the wet method, , (a) By the dry method in which the sample under test is not dissolved and, (b) By the wet method in which the sample under test is first dissolved and then analyzed to determine, its composition., The dry method is usually used as preliminary tests in the qualitative analysis., The semi-micro qualitative analysis is carried out using apparatus such as: test tubes, beakers,, evaporating dish, crucible, spot plate, watch glass, wire gauze, etc., , Brother’s Academy, Amalner [Chemistry: I], , 2

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02. Introduction to Analytical Chemistry, There are two types of qualitative analysis: (a) Organic, , Std: XI, &, , (B) Inorganic, , The qualitative analysis of organic & inorganic compounds involves different types of tests. The, majority of organic compounds are composed of a relatively small number of elements such as carbon,, hydrogen, oxygen, nitrogen, sulphur, halogen, phosphorus. Elementary qualitative analysis is concerned, with the detection of the presence of these elements. The identification of an organic compound, involves tests such as detection of functional group, determination of melting or boiling point, etc., The qualitative analysis of simple inorganic compounds involves detection and confirmation of cationic, and anionic species i.e. basic and acidic radicals., , Chemical methods of quantitative analysis: ⇒, , Quantitative analysis of organic compounds involves methods such as determination of percentage of, constituent elements, concentrations of unknown compound in the given sample, etc., Qualitative analysis of simple inorganic compounds involves methods such as decomposition reaction, (gravimetric analysis), the progress of reaction between two solutions till its completion (titrametric or, volumetric analysis), etc. The quantitative analytical methods involve measurement of quantities such as, mass and volume using some apparatus such as weighing machine, burette, etc., , III), , Mathematical operation and error analysis:⇨, , The accuracy of measurement is of a great concern in analytical chemistry. This is because faulty, equipment, poor data processing or human error can lead inaccurate measurements. Also, there can be, intrinsic error in the analytical measurements., When measurements are not accurate, this provides incorrect data that can lead to wrong conclusions., e.g., , If a laboratory experiments requires a specific amount of a chemicals, then measuring the wrong amount, may results in an unsafe or unexpected outcome., Hence, the numerical data obtained experimentally are treated mathematically to reach the some, quantitative conclusions., Also an analytical chemist has to know how report the quantitative analytical data, indicating the, extent of the accuracy of measurement, perform the mathematical operation & properly express the, quantitative error in the result., , Scientific notation (Exponential notation): ⇒, , A chemist has to deal with numbers are expressed as large as 602,200,000,000,000,000,000,000 for the, molecules of 2 gm of hydrogen gas or as small as 0.00000000000000000000000166 gm that is mass of Hatom. To avoid the writing so many zeros in the mathematical operations, scientific notations i.e., exponential notations are used., n, In scientific notations, numbers are expressed in the form of N × 10 , where n is an exponent with, , positive or negative values & N can have a value between 1 to 10., , Brother’s Academy, Amalner [Chemistry: I], , 3

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02. Introduction to Analytical Chemistry, e.g., , Std: XI, 23, , (a) The number 602,200,000,000,000,000,000,000 is expressed as 6.022 × 10 ., , (b) The mass of H-atom, 0.00000000000000000000000166 gm is expressed as 1.66 × 10—24 gm, 2, (c) The number 123.456 is written as 1.23456 × 10 ., , (d) The number 0.00015 is written as 1.5 × 10—4., , Here the decimal has to be moved four places to the right and — 4 is the exponent in the scientific, , notation., Now let us perform mathematical operations on numbers expressed in scientific notation., , , , Addition and subtraction:To perform addition or subtraction operation, first numbers are written in such a way that they have the, same exponent. The coefficients are then added or subtract., , e.g., , 4, , 3, , 4, , 4, , a) For adding 5.55 × 10 and 6.95 × 10 , first the exponent is made equal. Thus, 5.55 × 10 + 0.695 × 10 ., Then these numbers can be added as follow;, , 4, , 4, , (5.55 + 0.695) × 10 = 6.245 × 10, , b) The subtraction of two numbers of can be done shown below;, —2, , 3.5 × 10, , — 5.8 × 10—3 = (3.5 × 10—2) — (0.58 × 10—2) = (3.5 — 0.58) × 10—2 = 2.92 × 10—2, , , , Multiplication:-, , e.g., , (a), (b), , (5.6 × 105) × (6.9 × 108) = (5.6 × 6.9) (10 5 + 8) = (5.6 × 6.9) × 1013 = 38.64 × 1013 = 3.864 × 1013, , (9.8 × 10—2) × (2.5 × 10—6) = (9.8 × 2.5) (10—2 + (—6)), —2 —6), , = (9.8 × 2.5) (10, , —8, , ) = 24.50 × 10, , —7, , = 2.45 × 10, , Precision and accuracy of measurement: ⇒, , Aim of any measurement is to get the actual value called true value or accepted value of a quantity., Nearness of the measured value to the true value is called the accuracy of measurement. Larger the, accuracy smaller the error. Accuracy depends upon the sensitivity or least count (The smallest quantity, that can be measured) of the equipment., e.g., , A burette reading of 10.2 mL. For all the three situations in the, given figure the reading would be noted is 10.2 mL. It means, that there is an uncertainty about the digit appearing after the, decimal point in the reading 10.2 mL. This is because the least, count of the burette is 0.1 mL. The meaning of the reading 10.2 mL, is that the true value of reading lies between 10.1 mL and 10.2 mL. This is indicated by writing 10.2 ± 0.1, mL. Here the burette reading has an error of ± 0.1 mL., , Errors may be expressed as absolute or relative error., Absolute error = Observed value — True value, , Relative error is generally a more useful quantity a more useful quantity than absolute error. Relative, , Brother’s Academy, Amalner [Chemistry: I], , 4

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02. Introduction to Analytical Chemistry, , Std: XI, , error is the ratio of an absolute error to the true value. It is expressed as a percentage., Relative error =, , 𝐀𝐛𝐬𝐨𝐥𝐮𝐭𝐞 𝐞𝐫𝐫𝐨𝐫, 𝐓𝐫𝐮𝐞 𝐯𝐚𝐥𝐮𝐞, , × 100%, , There can be error in a measurement due to a number of reasons including inefficiency of the person, doing measurement., Multiple readings of the same quantity are noted to minimize the error. If the readings match, closely, they are said to have high precision. High precision implies reproducibility of the readings., High precision is a prerequisite for high accuracy. Precision is expressed in terms of deviation. An, absolute deviation is the modulus of the difference between an observed value and the arithmetic, mean for the set of several measurements made in the same way. It is a measure of absolute error in, the repeated observation., Absolute deviation = │Observed deviation — Mean │, Arithmetic mean of all the absolute deviations is called the mean absolute deviation in the measurements., The ratio of means is called relative deviation., Relative deviation =, , , , 𝐌𝐞𝐚𝐧 𝐚𝐛𝐬𝐨𝐥𝐮𝐭𝐞 𝐝𝐞𝐯𝐢𝐚𝐭𝐢𝐨𝐧, 𝐌𝐞𝐚𝐧, , Distinguish between accuracy & precision., , × 100 %, , No., , Accuracy, , Precision, , 1., , Accuracy refers to nearness of the measured, value to the true value., , Precision refers to closeness of the multiple, readings of the same quantity., , 2., , Accuracy represents error with respect to true, , Precision is represents error in the repeated, , value., , measurement., , Accuracy is expressed in terms of absolute error, , Precision is expressed in the term of, , & relative error., , absolute deviation & relative deviation., , 3., , Significant figures: ⇒, , a), , Uncertainty in measured value leads to uncertainty in calculated result., , b), , Uncertainty in a value is indicated by mentioning the number of significant figures in that value., , e.g., , Consider the column reading 10.2 ± 0.1 mL recorded on burette having the least count of 0.1 mL. Here, it, , is said that the last digit ‘2’ in the reading is uncertain; its uncertainty is ± 0.1 mL. On the other hand,, the figure ‘10’ is certain., , c), , The significant figures in a measurement or result are the number of digits known with certainty plus, one uncertain digit., , d), , In a scientific experiment, a result is obtained by doing calculation in which values of a number of, quantities measured with equipment of different least counts are used., , , , Significant figures: - The significant figures in a measurement or result are the number of digits, known with certainty plus one uncertain digit., , , , Rules for deciding significant figures :-, , Brother’s Academy, Amalner [Chemistry: I], , 5

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02. Introduction to Analytical Chemistry, , Std: XI, , i), , All non-zero digits are significant., , ii), , All zeros between two non-zero digits are significant., , iii), , Zeros on the left of the first non-zero digit are not significant. Such a zero indicates the position of the, decimal point., , iv), , e.g. 127.34 gm contains five significant figures., e.g. 120.07 m contains six significant figures., , e.g. 0.025 has two significant figures, 0.005 has one significant figure., , Zeros at the end of a number are significant if they are on the right side of the decimal point., e.g. 0.0400 gm has three significant figures & 400 gm has one significant figure., , v), , In numbers written is scientific notation, all digits are significant., 2, —5, 2.035 × 10 has four significant figures & 3.25 × 10 has three significant figures., , e.g., , Calculations with significant figures: ⇒, , When performing calculations with measured quantities, the rule is that the accuracy of the final result, is limited to the accuracy of the least accurate measurement. In other words, the final result cannot be, more accurate than the least accurate number involved in calculations. Sometimes, the final result of a, calculation often contains figures that are not significant. When this occurs, the final result is rounded off., The following rules are used to round off a number to the required number of significant figures:, (a), , If the digit following the last digit to be kept is less than five, the last digit is left unchanged., , e.g., , 46.32 rounding off to two significant figures is 46., , (b), , If the digit following the last digit to be kept is more than five, the last digit to be kept increased by one., , e.g., , 52.87 rounded to three significant figures is 52.9., , (c), , If the digit following the last digit to be kept five, then the last digit increased by one if it is odd & it is, not changed if it is even., , , 1), , Significant figures in calculations:-, , For addition & subtraction of significant figures: - The maximum number of, digits to the right of the decimal point in the result should not be greater, than either of the original number., , e.g., , The final answer should be reported only up to one digit after the decimal point (since 18.5, have only one digit after the decimal point). So answer is 46.1., 2), , Multiplication & Division of significant figures: - The result is reported with the, same number of significant figures as there are in the measurement with the, few significant figures., , e.g., , Since the fewest number of significant figures are two (3.4), the result should be reported as 58., , , , Dimensional analysis:-, , The dimensional analysis or factor label method or unit factor method is basically used to, convert units from one system to other., e.g. a) Converting inch to cm: -, , Unit factor:, , 2.54 cm/ 1 cm, , b) Converting cm to inch: -, , Unit factor:, , 1 inch / 2.54 cm, , Brother’s Academy, Amalner [Chemistry: I], , 6

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02. Introduction to Analytical Chemistry, IV), , Std: XI, , Determination of molecular formula:⇨, , Molecular formula of a compound is the formula which indicates the actual number of atoms of the, constituent elements in a molecule., It can be obtained from the experimentally determined values of percent elemental composition, and molar mass of that compound., , Percent composition & empirical formula: ⇒, a), , i), , Percentage composition:, , The percentage composition of a compound is the percentage by weight of each element present in the, compound., , ii), , Quantitative determination of the constituent element by suitable methods provides the percent, elemental composition of a compound., , iii), , If the percent total is not 100, the difference as percentage oxygen., , iv), , From the percentage, the ratio of the atoms of the constituent elements in the molecule is calculated., , b), , Empirical formula:, , The simplest ratio of atoms of the constituent elements in a molecule is called the empirical formula, e.g., , The empirical formula of benzene is CH., , c), (i), , Molecular formula:, , Molecular formula of a compound is the formula which indicates the actual number of atoms of the, constituent elements in a molecule., , e.g., , Molecular formula of benzene is C6H6., , (ii), , It can be obtained from the experimentally determined values of percentage elemental composition &, the molar mass of that compound., , (iii), , Molecular formula can be obtained from the empirical formula if the molar mass is known., Molecular formula = r × Empirical formula, r=, , V), (a), , 𝐌𝐨𝐥𝐞𝐜𝐮𝐥𝐚𝐫 𝐟𝐨𝐫𝐦𝐮𝐥𝐚, 𝐄𝐦𝐩𝐢𝐫𝐢𝐜𝐚𝐥 𝐟𝐨𝐫𝐦𝐮𝐥𝐚, , Chemical reactions and stoichiometric calculations:⇨, , Stoichiometry: - The study of quantitative relation between the amount of reactants & products is, called stoichiomeytry., , (b), , Stoichiometric calculations: - Calculations based on balanced chemical equations to calculate the, amount of reactants & products are known as stoichiometric calculations., Balanced chemical equation is symbolic representation of a chemical reaction. It provides the, following information, which is useful in solving problems based on chemical equations:, , i), , It indicates the number of moles of the reactants involved in a chemical reaction & the number of, , Brother’s Academy, Amalner [Chemistry: I], , 7

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02. Introduction to Analytical Chemistry, , Std: XI, , moles the products formed., ii), , It indicates the relative masses of the reactants & products linked with chemical changes., , iii), , It indicates the relationship between the volume/s of the gaseous reactants & products, at STP., Hence, balanced chemical equation is useful in solving problems based on chemical equations., , Stoichiometric problems: ⇒, , Generally problems based on stoichiometry are of the following types:, a), , Problems based on mass-mass relationship., , b), , Problems based on mass-volume relationship., , c), , Problems based on volume-volume relationship., , , , Steps involved in problems based on stoichiometric calculations:, , 1), , Write down the balanced chemical equation representing the chemical reaction., , 2), , Write the number of moles and the relative masses or volumes of the reactants & products below the, respective formulae., , 3), , Relative masses or volumes should be calculated from the respective formula mass referring to, condition of STP., , 4), , Apply the unitary method to calculate the unknown factor/s as required by the problem., , VI), , , Limiting reagent: ⇨, , Limiting reagent: - The reactant which gets consumed & limits the amount of the product formed is, called the limiting reagent., , , , Explanation:-, , i), , When a chemist carries out a reaction, the reactants are not usually present in exact stoichiometric, amounts, i.e. in the proportions indicated by the balanced equation., , ii), , This is because the goal of a reaction is to produce maximum quantity of a useful compound from the, starting materials. Frequently, a large excess of one reactant is supplied to ensure that the most, expensive reactant is completely converted into the desired product., , iii), , The reactant which is present in lesser amount gets consumed after some time & subsequently, no, further reaction takes place, whatever be the amount left of the other reactant present., Hence, limiting reagent is the reactant that gets consumed entirely & limits the reaction., , e.g., , Consider the formation of nitrogen dioxide (NO2) from nitric oxide (NO) & oxygen., , Suppose initially we take 8 moles of NO & 7 moles of O 2., To determine the limiting reagent, calculate the number of moles of NO 2 produces from the given, initial quantity of NO & O2. The limiting reagent will yield the smaller amount of the product., , Brother’s Academy, Amalner [Chemistry: I], , 8

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02. Introduction to Analytical Chemistry, , Std: XI, , Starting with 8 moles of NO, the number of moles of NO 2 produced is,, 8 mol NO ×, , 𝟐 𝐦𝐨𝐥 𝐍𝐎𝟐, 𝟐 𝐦𝐨𝐥 𝐍𝐎, , = 8 mol NO2, , Starting with 7 moles of O 2, the number of moles of NO2 produced is,, 7 mol O2 ×, , 𝟐 𝐦𝐨𝐥 𝐍𝐎𝟐, 𝟏 𝐦𝐨𝐥 𝐎𝟐, , = 14 mol NO2, , Since 8 moles NO result in a smaller amount of NO 2, NO is the limiting reagent & O 2 is the excess, reagent, before reaction has started., , , , Excess of reagent: - The reactant taken in excess which remains un-reacted in a chemical reaction is, called as excess of reagent., , VII), , Concentration of solution: ⇨, , A majority of reactions in the laboratory are carried out in solutions. Therefore, it is important to, understand how the amount of substance is expressed when it is present in the form of a solution. The, concentration of a solution or the amount of substance present in given volume of a solution can be, expressed in any of the following ways:, (i), (iii), , Mass or weight percentage (W/W %), Molarity (M), , (ii), (iv), , Mole fraction (), Molality (m), , Mass percent (W/W %): ⇒, , It is obtained by using following relation:, , Mass or weight percentage (W/W %) =, , 𝐌𝐚𝐬𝐬 𝐨𝐟 𝐬𝐨𝐥𝐮𝐭𝐞, , 𝐌𝐚𝐬𝐬 𝐨𝐟 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧, , × 100, , Mole fraction ():⇒, , The ratio of number of moles of any component in the solution to the number of moles of solute &, solvent (solution) is called as mole fraction of any component., , It is denoted by ., , Mathematically it can be expressed,, 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐦𝐨𝐥𝐞𝐬 𝐨𝐟 𝐜𝐨𝐦𝐩𝐨𝐧𝐞𝐧𝐭, ,  Mole fraction =, , 𝐍𝐮𝐦𝐛𝐞𝐫 𝐨𝐟 𝐦𝐨𝐥𝐞𝐬 𝐨𝐟 𝐬𝐨𝐥𝐮𝐭𝐞 𝐚𝐧𝐝 𝐬𝐨𝐥𝐯𝐞𝐧𝐭 𝐢𝐧 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧, , Consider a solution contain n1 moles of solvent & n2 moles of solute. Hence total numbers of moles, in the solution are n1 + n2., Thus,, , mole fraction of solvent ( 1) =, mole fraction of solute ( 2) =, ,  1 +  2 =, , 𝐧𝟏, , 𝐧𝟏 + 𝐧𝟐, , +, , 𝐧𝟐, , 𝐧𝟏 + 𝐧𝟐, , 𝐧𝟏, , 𝐧𝟏 + 𝐧𝟐, 𝐧𝟐, , 𝐧𝟏 + 𝐧𝟐, , =1, , Hence the sum of mole fractions of all components in the solution is unity., Mole fraction is independent of temperature & it has no unit., , Brother’s Academy, Amalner [Chemistry: I], , 9

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02. Introduction to Analytical Chemistry, , Std: XI, , VIII) Use of graph in analysis:⇨, Analytical chemistry often involves deducing some relation between two or more proportion of, matter under study., e.g., , The relation between temperature & volume of a given amount of gas., A set of experimentally measured values of volume &, temperature of a definite mass of a gas upon plotting, on a graph paper appears as given below;, , When the points are directly connected, a, a zig-zag pattern results as shown below;, , A smooth curve (or average curve) passing through these points, can be drawn as shown below. The traight line is consistent, with the V  T., , While fitting the points into a smooth curve all the plotted points should be evenly distributed. This, can be verified mathematically, by drawing a perpendicular from each point to the curve. The, perpendicular represents deviation of each point from the curve. Take sum of all the perpendicular on, side of the line & sum of all the perpendiculars on another side of the line separately. If the two sums, are equal (or nearly equal), the curve drawn shows the experimental points in the best possible, representation., , *, , *, , *, , Brother’s Academy, Amalner [Chemistry: I], , *, , *, 11

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02. Introduction to Analytical Chemistry, , Std: XI, , Numerical Problems, 1), , Express the following quantities in exponential terms:, (a) 0.0003498, , 2), , (b) 235.4678, , (c) 70000.0, , (d) 1569.00, , Give the number of significant figures in each of the following:, a), , 4, , 1.230 × 10, , c) 1.23 × 104, , b) 0.002030, , d) 1.89 × 10—4, , 3), , Express the quantities in above question (2) with without exponents as the case may be., , 4), , Find out the molar masses of the following compounds:, a), , Copper sulphate crystal (CuSO 4•5H2O), , [Ans.: 249.5 gm/mol], , b), , Sodium carbonate, decahydrate (Na2CO3•10H2O), , [Ans.: 286 gm/ mol], , c), , Mohr’s salt [FeSO4 (NH4) 2SO4•6H2O], , [Ans.: 392 gm/mol], , {Atomic Mass: Cu = 63.5, S = 32, O = 16, H = 1, Na = 23, C = 12, Fe = 56, N = 14}, 5), , Work out the percentage composition of constituents elements in the following compounds:, a., , Lead phosphate [Pb3 (PO4) 2],, , b. Potassium dichromate (K 2Cr2O7), , c., , Macrocosmic salt: Sodium ammonium hydrogen phosphate, tetrahydrate (NaNH 4HPO4•4H2O), , {Atomic Mass: Pb = 207, P = 31, O = 16, K = 39, Cr = 52, Na = 23, N = 14}, [Ans.: (a) (1) % composition of Pb = 76.57 %, (2) % composition of p = 7.64 %, (3) % composition of O =, 15.78 %, (b) (1) % composition of K = 26.53 %, (2) % composition of Cr = 35.37 %, (3) % composition of, O = 38.10 %, (c) (1) % composition of Na = 11.00 %, (2) % composition of N = 6.70 %, (3) % composition, of H = 6.22 %, (4) % composition of P = 14.83 %, (5) % composition of O = 61.24%,], 6), , Find the percentage composition of constituent green vitrol crystals (FeSO 4•7H2O). Also find out the, mass iron & water of crystallization in 4.54 kg of the crystals., , {At. Mass : Fe = 56, S = 32, O = 16}, , [Ans.: Mass of Fe = 0.915 Kg, mass of 7H2O = 2.058 Kg], 7), , The red colour of blood is due to a compound called ‘haemoglobin’. It contains 0.335% of iron. Four, atoms of iron are present in one molecule haemoglobin. What is its molecular weight?, {At. Mass: Fe = 55.84}, , 8), , [Ans.: Molar mass = 66674.6 gm/mol], , A substance, on analysis, gave the following percent composition: Na = 43.4%, C = 11.3% & O = 45.3%., Calculate the empirical formula. {At. Mass: Na = 23u, C = 12u, O = 16 u} [Ans.: Na2CO3], , 9), , Assuming the atomic weight of a metal M to be 56, find the empirical formula of its oxide containing, 70.0% of M., , 10), , [Ans.: M2O3], , 1.00 gm of a hydrated salt contains 0.2014 gm of iron, 0.1153 gm of sulfur, 0.2301 gm of oxygen &, 0.4532 gm of water of crystallization. Find the empirical formula., , {At. Mass: Fe = 56, S = 32, O = 16}, , [Ans.: FeSO4], 11), , An organic compound containing oxygen, hydrogen & nitrogen contains 20% carbon, 6.7% hydrogen &, , Brother’s Academy, Amalner [Chemistry: I], , 12

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02. Introduction to Analytical Chemistry, , Std: XI, , 46.67% nitrogen. Its molecular mass was found to be 60. Find the molecular formula of the compound., [Ans.: CH4N2O], 12), , A compound on analysis gave the following percentage composition by mass: H = 9.09; O = 36.36; C =, 54.55. Molar mass of compound is 88. Find its molecular formula. [Ans.: Molecular formula = C 4H8O2], , 13), , Carbohydrates are compounds containing only carbon, hydrogen & oxygen. When heated in the, absence of air these compounds decompose to form carbon & water. If 310 gm of a carbohydrate leaves, a residue 124 gm of carbon on heating in absence of air, what is the empirical formula of the, carbohydrate?, , 14), , [Ans.: CH2O], , Write each of the following in exponential notation:, (a) 3,672,199, , 15), , (b) 0.000098, , —3, , (e) 0.011 × 10, , —1, , (c), , (c) 5.16 × 10, , —2, , (f) 14.3 × 10, , 𝟏, , (d) 43.71 × 10, , (h) 5.00858585, , 𝟏.𝟒 × 𝟏𝟎𝟗, , (d), , (𝟐.𝟕𝟕 × 𝟏𝟎𝟑)(𝟑.𝟕𝟔 × 𝟏𝟎𝟓), , 𝟑𝟑, , 𝟗.𝟎𝟎 × 𝟏𝟎−𝟒, , (𝟒 × 𝟏𝟎−𝟑 )(𝟗.𝟗 × 𝟏𝟎−𝟕 ), , (𝟕𝟖𝟗) (𝟏.𝟎𝟎𝟐 × 𝟏𝟎−𝟏𝟎) (𝟎.𝟑 × 𝟏𝟎−𝟐 ), , Perform each of the following calculations. Round off your answers to three digits:, , (c), , 𝟖.𝟗𝟒 × 𝟏𝟎𝟔, , 𝟒.𝟑𝟓 × 𝟏𝟎𝟒, , (b), , (8.39 107) (4.53 109), , (d), , (𝟗.𝟐𝟖 × 𝟏𝟎𝟗)(𝟗.𝟗 × 𝟏𝟎−𝟕 ), , Perform each of the following operations., , (𝟓𝟏𝟏) (𝟐.𝟗𝟖 × 𝟏𝟎−𝟔 ), , (a) 3.971 × 107 + 1.98 × 104, —4, , 19), , 5, , (g) 0.00477 × 10, , (b), , 𝟑.𝟒𝟎 × 𝟏𝟎𝟐𝟒, , (a) (3.26 104) (1.54 106), , 18), , —4, , 4, , (b) 3.75 × 10, , Perform each of the following calculations. Round off your answers to two digits:, (a), , 17), , (d) 198.75, , Write each of the following numbers in ordinary decimal form:, (a) 3.49 × 10—11, , 16), , (c) 0.00461, , (b) 1.05 × 10, , — 9.7 × 10—5, , (c) 4.11 × 10—3 + 8.1 × 10—4, , (d) 2.12 × 106 — 3.5 × 105, , A 1.000 mL sample of acetone, a common solvent used as a paint removal, was placed in a small bottle, whose mass was known to be 38.0015 gm. The following values were obtained when the acetone-filled, bottle was weighed: 38.7798 gm, 38.7795 gm & 38.7801 gm. How would you characterize the precision, & accuracy of these measurements if the actual mass of the acetone was 0.7791 gm?, , 20), , [Ans.: ± 0.07736%, 0.1027 %], , Your laboratory partner was given the task of measuring the length of a box (approx 5 in) as accurately, as possible, using a meter stick graduated in millimeters. He supplied you with following measurements:, 12.65 cm, 12.6 cm, 12.65 cm, 12.655 cm, 126.55 mm, 12 cm., , 21), , a), , State which of the measurements you would accept, giving the reason., , b), , Give your reason for rejecting each of others., , [Ans.: 12.6 cm], , What weight of calcium oxide will be formed on heating 19.3 gm of calcium carbonate?, , Brother’s Academy, Amalner [Chemistry: I], , 13

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02. Introduction to Analytical Chemistry, , Std: XI, , {Atomic Wt.: Ca = 40, C = 12, and O = 16}, 22), , [Ans.: 10.8 gm], , The hourly energy requirements of an astronaut can be satisfied by the energy released when 34 gm of, sucrose are ‘burnt’ in his body. How many grams of oxygen would be needed to be carried in space, capsule to meet his requirement for one day?, , *, , *, , [Ans.: 916.21 gm], , *, , *, , *, , IMP Questions on Introduction to Analytical Chemistry, , Q. No., , Question, , Marks, , 1., , Define Analytical chemistry. Why is accurate measurement crucial in science?, , 2, , 2., , How is Analytical chemistry useful?, , 2, , 3., , What is Qualitative analysis?, , 1, , 4., , What Quantitative analysis?, , 1, , 5., , What is chemical analysis? Discuss the importance of chemical analysis?, , 3, , 6., , What are the applications of analytical chemistry?, , 2, , 7., , What is meant by semi-microanalysis? What are the two types of semi-microanalysis?, , 2, , 8., , Mention the apparatus used to carry out semi-micro qualitative analysis?, , 1, , 9., , Which methods are included in the classical methods of analysis?, , 2, , 10., , How is the chemical analysis of a sample carried out?, , OR, , 2, , What are the stages involved in the chemical analysis of a sample?, 11., , What are the tests involved in the qualitative analysis of organic compounds?, , 2, , 12., , What is meant by the qualitative analysis of inorganic compounds?, , 2, , 13., , What are the tests involved in the quantitative analysis of organic compounds?, , 2, , 14., , What are quantitative analytical methods?, , 1, , 15., , How is the quantitative analysis of inorganic compounds carried out?, , 2, , What is meant by accuracy of measurement?, , OR, , 16., , 2, Define accuracy of measurement. How important is accuracy in measurement?, , 17., , What care should be taken by an analytical chemist while presenting data?, , 2, , 18., , How are scientific notations useful in presenting data? Explain giving examples., , 3, , Brother’s Academy, Amalner [Chemistry: I], , 14

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02. Introduction to Analytical Chemistry, 19., 20., , Std: XI, , Define least count., , 1, , ‘Accuracy depends upon the sensitive or least count of the measuring equipment’. Explain, , 3, , this statement with a suitable example., 21., , How is accuracy of a measurement expressed?, , 1, , 22., , What is the difference between absolute error and relative error?, , 2, , 23., , Define Precision., , 1, , 24., , Distinguish between accuracy and precision, , 2 or 3, , 25., , What is meant by precision?, , 2, , 26., , How is precision expressed?, , 2, , 27., , What is meant by absolute deviation in measurements?, , 1, , 28., , What is meant by relative deviation in measurements?, , 1, , 29., , What do you mean by significant figures? State the rules for deciding significant figures., , 3, , 30., , What is the relation between the least count of an instrument and accuracy?, , 1, , 31., , State the rules needed for rounding off figures during calculations., , 2, , 32., , What is meant by the percent elemental composition of a compound?, , 1, , 33., , Explain the terms percentage composition, empirical formula & molecular formula., , 3, , What is the relationship between empirical formula and molecular formula?, 34., , 2, Give suitable example., , 35., , What is a balanced chemical equation?, , 1, , 36., , Define Stoichiometry., , 1, , 37., , What are stoichiometric calculations?, , 1, , 38., , What information is provided by a balanced chemical equation?, , 3, , 39., , Mention the steps involved in the problems based on stoichiometric calculations., , 2, , 40., , What is a limiting agent? Explain., , 3, , 41., , What is meant by an excess reagent?, , 1, , 42., , Which reagent is the limiting reagent in a reaction? Explain giving a suitable example., , 3, , What are the different ways of expressing the concentration of a solution?, 43., , OR, 2, , How is concentration of a solution expressed?, 44., , Explain the following terms: (a) Mole fraction (b) Molarity (c) Molality, , 3 (1 mark, each ), , 45., , What is meant by mass percentage or weight percentage?, , 2, , 46., , Why does the molarity of the solution depends upon temperature?, , 1, , Brother’s Academy, Amalner [Chemistry: I], , 15