Question 1. Calculate the mass of 6. Solution — No. Question 6. An atom of some element X weighs 6. Calculate the number of gram-atoms in 40 kg of it. Question 7. Total no. Question 8. Calculate the volume occupied by 1 mole atom of i monoatomic gas, and ii diatomic gas at NTP.
Solution — 1 mole atom of monoatomic gas occupies Question Solution — 6. Calculate the number of atoms in 5. In monoatomic gases, No. In diatomic gases, No. Calculate the number of sulphate SO 4 2- ions in mL of 0. Calculate the standard molar volume of oxygen gas.
Calculate the mass of 1 mole He gas. The density of He gas at NTP is 0. A metal M of atomic mass Calculate the apparent volume occupied by one atom of the metal. Calculate the number of oxygen atoms and its mass in 50 g of CaCO 3. Equal masses of oxygen, hydrogen and methane are taken in a container in identical conditions.
Find the ratio of the volumes of the gases. Let X g of each gas is taken. The atomic masses of two elements A and B are 20 and 40 respectively. Oxygen is present in a 1-liter flask at a pressure of 7. Calculate the number of oxygen molecules in the flask.
Mole Concept and Stoichiometry Solutions for ICSE Board Class 10 Science
Calculate approximately the diameter of an atom of mercury, assuming that each atom is occupying a cube of edge length equal to the diameter of the mercury atom. The density of mercury is Download as PDF. Mass of one atom of the element A is 3. How many atoms are contained in 1 gm of the element A?
Density of a 2. The molality of the solution is:. If water sample are taken from sea, rivers or lake, they will be found to contain hydrogen and oxygen in the approximate ratio of 1 : 8.
This indicates the law of :. Hydrogen and oxygen combine to form H2O2 and H2O containing 5. The data illustrates :. It is known that atom contain protons, neutrons and electrons. If the mass of neutron assumed to half of its original value whereas that of proton is assumed to be twice its of original value then the atomic mass of will be :.
The dot at the end of this sentence has a mass of about one microgram. Assuming that the black stuff is carbon, number of atoms of carbon needed to make such a dot is approximately. If 10 21 molecules are removed from mg of CO 2then the number of moles of CO 2 left are.
The gas may be. View all posts by india india. You are commenting using your WordPress. You are commenting using your Google account.
You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. Skip to content. Download as PDF 1. The data illustrates : a Law of conservation of mass b Law of constant proportion c Law of reciprocal proportion d Law of multiple proportion 5.
Total number of moles oxygen atoms in 3 litre O3 g at C and 8. One atoms of an element x weigh 6. Which of the following contains the largest mass of hydrogen atoms? If the mass of neutron assumed to half of its original value whereas that of proton is assumed to be twice its of original value then the atomic mass of will be : a Same b How many molecules are present in one gram of hydrogen?
The number of oxygen atoms is 4. Share this: Twitter Facebook. Like this: Like Loading Published by india india. Leave a Reply Cancel reply Enter your comment hereMole Methods to calculate mole Laws of chemical combination Significance of chemical equation Limitingreagent Problems related with mixture Percentage Yield Percentage purity Problems related with sequential reaction Problems related parallel reaction Principle of atom conservation Average atomic Mass Average molecular mass Empirical and molecular formula Experimental methods for determination.
MOLE A mole is the amount of substance that contains as many species [Atoms, molecules, ions or other particles] as there are atoms in exactly 12 gm of C Exercise a What is the mass of one atom of S? Mass of one molecule of the substance in amu 1 [Mass of an atom of C - 12] Illustration a What is the mass of one molecule of HNO3? Exercise a What is the mass of one molecule of H2SO4. Illustration A piece of Cu contains 6.
How many mole of Cu atoms does it contain? Exercise 5 mole of CO2 are present in a gaseous sample. How many molecules of CO2 are present in the sample? Although many books are still using the condition of 1 atm and K for STP. If volume is given under any other condition of temperature and pressure, then use the ideal gas equation to find the no.
Units of temperature :. How many mole of He are present in the sample? Note : We can use the following relationship as per requirement of question. Illustration How many molecules of O2 are present in 5. This relationship holds good when reactants are completely converted into products. Illustrations 1. Show that these results illustrate the law of conservation of mass. Exercise If 6. The residue is found to weigh 18 gram. What is the mass of CO2 released in this reaction?
Limitations : In case of isotopes, ratio is not fixed e. The resulting solution was dried and ignited when 1. In another experiment 2. Show that the above data are in accordance with law of constant composition? Exercise 7. In another experiment, The weight of cupric oxide formed was The mole concept is one of the topics with which you leave your preparation of physical chemistry in class One of the reasons for it being taught earlier is that the concept of mole will be required in almost every other topic of physical chemistry that you study later, irrespective of the complexity of that topic.
Apart from its relations in chemistry, it must be noted that mole concept is one of the easier topics in chemistry, so, make sure you do study it well and go through each and every point in this topic. So, when someone claims of a matter to be of One mole in quantity, that implies that the matter under consideration contains exactly 6.
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Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Skip to content. We Heartily Thank full for Your Decision! Reply Leave a Reply Cancel reply Your email address will not be published.The identity of a substance is defined not only by the types of atoms or ions it contains, but by the quantity of each type of atom or ion. For example, water, H 2 O, and hydrogen peroxide, H 2 O 2are 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 experimental approach required the introduction of a new unit for amount of substances, the molewhich remains indispensable in modern chemical science.
The mole is an amount unit similar to familiar units like pair, dozen, gross, etc. It provides a specific measure of the number of atoms or molecules in a bulk sample of matter. A mole is defined as the amount of substance containing the same number of discrete entities atoms, molecules, ions, etc. The mole provides a link between an easily measured macroscopic property, bulk mass, and an extremely important fundamental property, number of atoms, molecules, and so forth.
The number of entities composing a mole has been experimentally determined to be [latex]6. Consistent with its definition as an amount unit, 1 mole of any element contains the same number of atoms as 1 mole of any other element. The masses of 1 mole of different elements, however, are different, since the masses of the individual atoms are drastically different.
Figure 1. Each sample contains 6. From left to right top row : From left to right bottom row : Because the definitions of both the mole and the atomic mass unit are based on the same reference substance, 12 C, the molar mass of any substance is numerically equivalent to its atomic or formula weight in amu. Per the amu definition, a single 12 C atom weighs 12 amu its atomic mass is 12 amu. This relationship holds for all elements, since their atomic masses are measured relative to that of the amu-reference substance, 12 C.
Extending this principle, the molar mass of a compound in grams is likewise numerically equivalent to its formula mass in amu Figure 2.As discussed in Chapter 1, the mass number is the sum of the numbers of protons and neutrons present in the nucleus of an atom.
The mass number is an integer that is approximately equal to the numerical value of the atomic mass. Although the mass number is unitless, it is assigned units called atomic mass units amu. Because a molecule or a polyatomic ion is an assembly of atoms whose identities are given in its molecular or ionic formula, the average atomic mass of any molecule or polyatomic ion can be calculated from its composition by adding together the masses of the constituent atoms. The average mass of a monatomic ion is the same as the average mass of an atom of the element because the mass of electrons is so small that it is insignificant in most calculations.
The molecular mass of a substance is the sum of the average masses of the atoms in one molecule of a substance. It is calculated by adding together the atomic masses of the elements in the substance, each multiplied by its subscript written or implied in the molecular formula.
Because the units of atomic mass are atomic mass units, the units of molecular mass are also atomic mass units. The procedure for calculating molecular masses is illustrated in Example 2. Among its many uses, ethanol is a fuel for internal combustion engines. B Taking the atomic masses from the periodic table, we obtain.
C Adding together the masses gives the molecular mass:. Alternatively, we could have used unit conversions to reach the result in one step:. The same calculation can also be done in a tabular format, which is especially helpful for more complex molecules:. Until recently, it was used as a refrigerant. The structure of a molecule of Freon is as follows:. Unlike molecules, which form covalent bonds, ionic compounds do not have a readily identifiable molecular unit.
Therefore, for ionic compounds, the formula mass also called the empirical formula mass of the compound is used instead of the molecular mass.
The formula mass is the sum of the atomic masses of all the elements in the empirical formula, each multiplied by its subscript written or implied. It is directly analogous to the molecular mass of a covalent compound. The units are atomic mass units. Atomic mass, molecular mass, and formula mass all have the same units: atomic mass units.
Calculate the formula mass of Ca 3 PO 4 2commonly called calcium phosphate.Avogadro's Number, The Mole, Grams, Atoms, Molar Mass Calculations - Introduction
This compound is the principal source of calcium found in bovine milk. The formula mass of this molecular unit is calculated by adding together the atomic masses of three calcium atoms, two phosphorus atoms, and eight oxygen atoms. B Taking atomic masses from the periodic table, we obtain. C Adding together the masses gives the formula mass of Ca 3 PO 4 2 :. We could also find the formula mass of Ca3 PO4 2 in one step by using unit conversions or a tabular format:. Calculate the formula mass of Si 3 N 4commonly called silicon nitride.
The Mole Concept & Stochiometry Notes in pdf
It is an extremely hard and inert material that is used to make cutting tools for machining hard metal alloys.
It also describes the law of multiple proportions, which states that the ratios of the masses of elements that form a series of compounds are small whole numbers.Do you need help with your Homework? Are you preparing for Exams? Study without Internet Offline. Download pdf for free! Loading More Solutions Get this solution now! Download our free PDF or App. Get Solution now! Class 10 Concise Chemistry Solutions.
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