Frank solutions for Chemistry - Part 2 [English] Class 10 ICSE chapter 5 - Mole Concept And Stoichiometry [Latest edition]

Prove the Following :
Oxygen is a diatomic molecule.

Prove the Following :
2 X V.D. = Molecular mass.

Prove the Following :
One mole of any gas contains th e same number of molecules.

State Gay-Lussac's law of combining volumes.

State: Avogadro's law

Define atomicity of a gas.

Differentiate between 2H and H₂

When stating the volume of a gas, the pressure and temperature should also be given. Why?

The relative atomic mass of Cl atom is 35.5 a.m.u. Explain this statement.

What is the value of Avogadro's number?

What is the value of molar volume of a gas at STP?

Define the term: Vapour density.

Define the term.

Molar volume

Define the term Relative atomic mass.

Define the term : Avogadro's number

What are the main applications of Avogadro's law?

The empirical formula of a compound is C₂H₅. Its vapour density is 29. Determine the relative molecular mass of the compound and hence its molecular formula.

How does Avogadro's law explain Gay - lussac's law of combining volumes?

Explain the term : Gram atom

Explain the term : Gram mole

Explain the term : Mole

Calculate the relative molecular mass of Potassium chlorate.
(use K = 39, Cl = 35.5, O = 16, C = 12, H = 1, Na = 23, N = 14, S=32)

Calculate the relative molecular mass of Sodium acetate
(use K = 39, Cl = 35.5, O = 16, C = 12, H = 1, Na = 23, N = 14, S= 32)

Calculate the relative molecular mass of Ammonium sulphate.
(use K = 39, Cl = 35.5, O = 16, C = 12, H = 1, Na = 23, N = 14, S= 32)

Calculate the relative molecular mass of Chloroform.
(use K = 39, Cl = 35.5, O = 16, C = 12, H = 1, Na = 23, N = 14, S= 32)

Explain the terms empirical formula and molecular formula.

Give the empirical formula of C₆H₆.

Give the empirical formula of: C₆H₁₂O₆

Give the empirical formula of C₂H₂

Give the empirical formula of CH₃COOH

Give three pieces of information conveyed by the formula H₂O.

What do you understand by the term mole? How many elementary units are in one mole of a substance?

Fill in the blank.
Molecular weight of a gas is twice its __________.

Fill in the blank
Mass of 22.4 litre of a gas at STP is __________.

Fill in the blank
One gram atom of an element contains ______ atoms.

Fill in the blank.
One a.m.u. is the mass of ______ atom of C^₁₂.

Fill in the blank
 Avogadro's number is equal to ______

Give example of compound whose:
Empirical formula is the same as the molecular formula.

Give example of compound whose:
Empirical formula is different from the molecular formula.

Nitrogen and oxygen gas react as illustrated by the equation given below: N₂ + O₂ → 2NO
Calculate the volume of each reacting gas required to produce 1400cm³ of nitric oxide.

Calculate the number of molecules in 12.8g of sulphur dioxide gas. Take Avogadro's number as 6 x 10²³.
[S = 32, 0 = 16 ]

Calculate the weight of one molecule of oxygen .
[Avogadro's number = 6 x 1023, O = 16 ]

Calculate the percentage composition of oxygen in lead nitrate [Pb(NO₃)₂]. [Pb = 207, N= 14, O = 16]

The usefulness of a fertilizer depends upon percentage of nitrogen present in it. Find which of the following is a better fertilizer:
(a) Ammonium nitrate [NH₄NO₃]
(b) Ammonium phosphate [(NH₄)₃PO₄ (N=14,H=1,O=16,P=31)

A compound of lead has following percentage composition, Pb = 90.66%, O = 9.34%. Calculate empirical formula of a compound. [Pb = 207, O = 16]

Empirical formula of a compound is CH₂O. If its empirical formula is equal to its vapour density, calculate the molecular formula of the compound.

Potassium nitrate on strong heating decomposes as under :
2KNO₃ → 2KNO₂ + O₂
Calculate : Weight of potassium nitrite formed.
(K = 39, 0 = 16, N = 14)

Potassium nitrate on strong heating decomposes as under :
2KNO₃ → 2KNO₂ + O₂
Calculate : Weight of oxygen formed when 5.05g of potassium nitrate decomposes completely.
(K = 39, 0 = 16, N = 14)

What is the volume occupied by 48g of oxygen gas at STP?

What is the volume occupied by 16g of sulphur dioxide. gas at STP?

Determine the  molecular mass of a gas if 5g of it occupy a volume of 4 L at STP.

What weight of sulphuric acid will be required to dissolve 3g of magnesium carbonate?
[Mg = 24, C =12, 0 = 16 ]
MgCO₃ + H₂SO₄ → MgSO₄ + H₂O+ CO₂

Calculate the percentage of water in ferrous sulphate crystals.
[Fe = 56, S = 32, O =16, H = 1].

An organic compound has the following percentage composition: C = 12.76%, H = 2.13%, Br = 85.11%. The vapour density of the compound is 94. Find out its molecular formula.

Two oxides of a metal (M) have 20.12% and 11.19% oxygen. The formula of the first oxide is MO. Determine the formula of the second oxide.

Calculate the volume of air at STP, required to convert 300 mL of sulphur dioxide to sulphur trioxide. Air contains 21% of oxygen by volume.

10g of NaCl solution is mixed with 17g of silver nitrate solution. Calculate the weight of silver chloride precipitated.
AgNO₃ + NaCl → AgCI + NaNO₃

A student puts his signature with graphite pencil. If the mass of carbon in the signature is 10^-12 g. Calculate the number of carbon atoms in the signature.

Under the same conditions of temperature and pressure you collect 2L of carbon dioxide, 3L of chlorine, 5L of hydrogen, 4L of nitrogen and 1L of sulphur dioxide. In which gas sample will there be :
a. The greatest number of molecules. 
b. The least number of molecules.
Justify your answer.

What volume of hydrogen sulphide at STP will burn in oxygen to yield 12.8g suIphurdioxide according to the equation?
2H₂S + 3O₂ → 2H₂O + 2SO₂

What volume of hydrogen sulphide at STP will burn in oxygen to yield 12.8g what volume of oxygen would be required for complete combustion?

Find the total percentage of oxygen in magnesium nitrate crystal Mg(NO₃)₂.6H₂O.
[H = 1, N = 14, O = 16, Mg = 24]

A compound contains 87.5% by mass of nitrogen and 12.5% by mass of hydrogen. Determine the empirical formula of this compound.

Is it possible to change the temperature and pressure of a fixed mass of a gas without changing its volume? Explain your answer.

Define or explain the meaning of term 'molar volume'.

What is the mass of nitrogen in 1000Kg of urea [CO(NH2)2] ?
[H = 1, C= 12, N= 14, O = 16]

Calculate the empirical formula of the compound having 37.6% sodium, 23.1% silicon and 39.3% oxygen.(Answer correct to two decimal places) (O = 16, Na = 23, Si = 28)

(NH₄)₂Cr₂O₇ → N₂ + Cr₂O₃ +4H₂O.
What volume of nitrogen at STP, will be evolved when 63g of ammonium dichromate is decomposed?
(H= 1, N = 14, 0 = 16, Cr = 52)

Calculate the percentage of boron (B) in borax (Na₂B₄O₇.10H₂O). [H = 1, B = 11, O = 16, Na = 23],
answer correct to 1 decimal place.

The compound A has the following percentage composition by mass: C =26.7%, O = 71.1%, H = 2.2%.
Determine the empirical formula of A.(Answer to one decimal place)  (H=1,C=12,O=16)

If the relative molecular mass of A is 90, what is the molecular formula of A?

Water can split into hydrogen and oxygen under suitable conditions. The equations representing the change is:  2H₂O(I) → 2H₂ (g) + O₂(g)
If a given experiment results in 2500cm³ of hydrogen being produced, what volume of oxygen is liberated at the same time under the same conditions of temperature and pressure?

Water can split into hydrogen and oxygen under suitable conditions. The equations representing the change is:  2H₂O(I) → 2H₂ (g) + O₂(g)
Ammonia burns in oxygen and the combustion in the presence of a catalyst may be represented as:
2NH₃ (g) +2^1/2O₂ (g) → 2NO (g) + 3H₂O (I)
What mass of steam is produced when 1.5 g of nitrogen monoxide is formed?

Concentrated nitric acid oxidizes phosphorous to phosphoric acid according to the following equation :
P + 5HNO₃ → H₃PO₄ + H₂O + 5NO₂
What mass of phosphoric acid can be prepared from 6 .2 g of phosphorous?

Concentrated nitric acid oxidizes phosphorous to phosphoric acid according to the following equation :
P + 5HNO₃ → H₃PO₄ + H₂O + 5NO₂
What mass of nitric acid will be consumed at the same time?

Concentrated nitric acid oxidizes phosphorous to phosphoric acid according to the following equation :
P + 5HNO₃ → H₃PO₄ + H₂O + 5NO₂
What will be the volume of steam at the same time measured at 760mm of Hg pressure and 273°C? [H=1, N=14, O=16, P=31]

Ammonia may be oxidized to ni trogen monoxide in the presence of a catalyst according to th e equation as:
4NH₃ + 5O₂ → 4NO + 6H₂O
If 27L of reactants are consumed, what volume of ni trogen monoxide is produced at the same temperature and pressure?

If a crop of wheat removes 20 Kg of nitrogen per hectare of soil, what mass of the fertilizer calcium nitrate,Ca(NO₃)₂ would be required to replace nitrogen in 10 hectare field? (N = 14, O = 16, Ca = 40)

A vessel contains N molecules of oxygen at a certain temperature and pressure. How many molecules of sulphur dioxide can the vessel accommodate at the same temperature and pressure?

Each of the two flasks contains 2.0 g of gas at the same temperature and pressure. One flask contains oxygen and the other hydrogen. Which sample contains the greater number of molecules?

If the hydrogen sample contains N molecules, how many molecules are present in oxygen sample?

If 112 cm³ of hydrogen sulphide is mixed with 120 cm³ of chlorine at STP, what is the mass of sulphur formed?
H₂S + Cl₂ → 2HCI + S

Washing soda has the formula Na₂CO₃.10H₂O.What is the mass of anhydrous sodium carbonate left when all the water of crystallization is expelled by heating 57.2 g of washing soda?

When excess lead nitrate solution was added to a solution of sodium sulphate, 15.1g of lead sulphate was precipitated. What mass of sodium sulphate was present in the original solution?
Na₂SO₄ + Pb(NO₃)₂ → PbSO₄ + 2NaNO₃
(H = 1, C = 12, O = 16, Na = 23, S = 32, Pb = 207)

Determine the empirical formula of the compound whose composition by mass is 42% nitrogen, 48% oxygen and 9% hydrogen.[N=14,O=16,H=1]

When gases react their volumes bear a simple ratio to each other, under the same conditions of temperature and pressure. Who proposed this gas law?

What volume of oxygen would be required for complete combustion of 100L of ethane according to the following equation?
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Chlorine, nitrogen, ammonia and sulphur dioxide gases are collected under the same conditions of temperature and pressure.
Copy the following table which gives the volumes of the gases collected, and the number of molecules (X) in 20L of nitrogen.You are to complete the table by giving the number of molecules in th e other gases, in terms of X.

Mention the term defined by the following sentence:
The mass of a given volume of gas compared to the mass of an equal volume of hydrogen.

The reaction 4N₂O + CH₄ → CO₂ + 2H₂O + 4N₂ takes place in the gaseous state. If the volumes of all the gases are measured at the same temperature, and pressure, calculate the volume of dinitrogen oxide (N₂O), required to give 150cm³ of steam.

Calculate the percentage of phosphorous in the fertilizer superphosphate, Ca(H₂PO₄)₂. [Ca = 40, H =1, P =31, O = 16] (Correct to 1 decimal place)

A metal M, forms a volatile chloride containing 65.5% Chlorine. If the density of the chloride relative to hydrogen is 162.5, find the molecular formula of the chloride. [M = 56, Cl = 35.5]

Samples of the gases O₂, N₂, CO₂ and CO under the same conditions of temperature and pressure contain the same number of molecules represented by X. The molecules of Oxygen, occupy V litres and have a mass of 8 g. Under the same conditions of temperature and pressure :
What is the volume occupied by : X molecules of N_2.

Samples of the gases O₂, N₂, CO₂ and CO under the same conditions of temperature and pressure contain the same number of molecules represented by X. The molecules of Oxygen, occupy V litres and have a mass of 8 g. Under the same conditions of temperature and pressure :
What is the volume occupied by : 3X molecules of CO? [C=12,N=14,O=16]

Samples of the gases O₂, N₂, CO₂ and CO under the same conditions of temperature and pressure contain the same number of molecules represented by X. The molecules of Oxygen, occupy V litres and have a mass of 8 g. Under the same conditions of temperature and pressure :
What is the mass of CO₂ in g?

Samples of the gases O₂, N₂, CO₂ and CO under the same conditions of temperature and pressure contain the same number of molecules represented by X. The molecules of Oxygen, occupy V litres and have a mass of 8 g. Under the same conditions of temperature and pressure:
In answering the above questions, which law have you used?

Calculate the percentage of platinum in ammonium chloroplatinate (NH₄)₂PtCl₆.
[N = 14, H = 1, Pt = 195, Cl =35.5]
(Give your answer correct to the nearest whole number)

The percentage composition of sodium phosphate, as determined by analysis is : 42.1% Na, 18.9% P, 39% of O. Find the empirical formula of the compound.
[H =1, N =14, Na = 23, P = 31, Cl = 35.5, Pt = 195]

What volume of oxygen is required to burn completely a mixture of 22.4 dm³ of methane and 11 .2 dm³ of hydrogen in to carbon dioxide and steam? Equations of the reactions are given below:
CH₄ + 2O₂ → CO₂ + 2H₂O
2H₂ + O₂ → 2H₂O

The gases hydrogen, oxygen, carbon dioxide, sulphur dioxide and chlorine are arranged in order of their increasing relative molecular mass. Given 8 g of each gas at STP, which gas will contain the least number of molecules and which gas the
most?

A flask contains 3.2g of sulphur dioxide. Calculate the following: The number of molecules of sulphur dioxide present in the flask.

A flask contains 3.2g of sulphur dioxide.Calculate the following : The moles of sulphur dioxide present in the flask.

A flask contains 3.2g of sulphur dioxide. Calculate the following : The volume occupied by 3.2g of sulphur dioxide at STP.

The reaction of potassium permanganate (VII) with acidified iron (II) sulphate is given below:
2KMno₄ + 10FeSO₄ + 8H₂O → K₂SO₄ + 2MnSO₄ + 5Fe2(SO₄)₃ + 8H₂O
If 15.8g of potassium permanganate (VII) was used in the reaction, calculate the mass of iron (II) sulphate used in the above reaction.

When heated, potassium permanganate decomposes according to the following equation:

\[\ce{2KMnO4 -> \underset{solid residue}{K2MnO4 + MnO2} + O2}\]

Some potassium permanganate was heated in test tube. After collecting one litre of oxygen at room temperature, it was found that the test tube had undergone a loss in mass of 1.32 g. If one litre of hydrogen under the same conditions of temperature and pressure has a mass of 0.0825 g, calculate the relative molecular mass of oxygen.

When heated, potassium permanganate decomposes according to the following equation:

\[\ce{2KMnO4 -> \underset{solid residue}{K2MnO4 + MnO2} + O2}\]

Given that the molecular mass of potassium permanganate is 158 g, what volume of oxygen (measured at room temperature) would be obtained by the complete decomposition of 15.8 g of potassium permanganate? (Molar volume at room temperature is 24 litres). [K = 39, Mn = 55, O = 16]

The equations given below relate to the manufacture of sodium carbonate (Molecular weight of Na₂CO₃ = 106).

1. \[\ce{NaCl + NH3 + CO2 + H2O -> NaHCO3 + NH4Cl}\]
2. \[\ce{2NaHCO3 -> Na2CO3 + H2O + CO2}\]

Equations (1) and (2) are based on the production of 21.2 g of sodium carbonate.

1. What mass of sodium hydrogen carbonate must be heated to give 21.2 g of sodium carbonate?
2. To produce the mass of sodium hydrogen carbonate calculated in (a), what volume of carbon dioxide, measured at STP, would be required?

The volumes of gases A, B, C and D are in the ratio, 1 : 2 : 2 : 4 under the same conditions of temperature and pressure.

1. Which sample of gas contains the maximum number of molecules?
2. If the temperature and pressure of gas A are kept constant, then what will happen to the volume of A when the number of molecules is doubled?
3. If this ratio of gas volume refers to the reactants and products of a reaction, which gas law is being observed?
4. If the volume of A is actually 5.6 dm³ at STP, calculate the number of molecules in the actual Volume of D at STP (Avogadro's number is 6 × 10²³).
5. Using your answer from (iv), state the mass of D if the gas is dinitrogen oxide (N₂O).

Calculate the percentage of nitrogen in aluminium nitride. [Al = 27, N = 14]

Determine the empirical formula of a compound containing 47.9‰ K, 5.5‰ beryllium and 46.6‰ fluorine by mass.

Given that the relative molecular mass of copper oxide is 80, what volume of ammonia (measured at STP) is required to completely reduce 120g of copper oxide? The equation for the reaction is :
3CuO + 2NH₃ → 3Cu + 3H₂O + N₂

Calculate the number of moles and number of molecules present in 1.4 g of ethylene gas. What is the volume occupied by the same amount of ethylene?

What is the vapour density of ethylene? (Avogadro's number = 6 x 10²³; Atomic weight of C = 12, H = 1; Molar volume = 22.4 litres at STP)

Calculate the percentage of sodium in sodium aluminium fluoride (Na₃AIF₆).
[F = 19, Na = 23, Al = 27]

560ml of carbon monoxide is mixed with 500ml of oxygen and ignited. The chemicaI equation for the reaction is as folIows:
2CO + O₂ → 2CO₂
Calculate the volume of oxygen used and carbon dioxide formed in the above reaction.

A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at STP)
NH₄NO₃ → N₂O + 2H₂O
What volume of dinitrogen oxide is produced at the same time as 8.96 L of steam?

A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at STP)
NH₄NO₃ → N₂O + 2H₂O
What mass of ammonium nitrate should be heated to produce 8.96L of steam?

A sample of ammonium nitrate when heated yields 8.96 litres of steam (measured at STP)
NH₄NO₃ → N₂O + 2H₂O
Determine the percentage of oxygen in the ammonium nitrate?

A compound 'X' consists of 4.8% of C and 95.2% of Br by mass.
Determine the empirical formula of this compound.
[C = 12, Br = 80]

A compound 'X' consists of 4.8% of C and 95.2% of Br by mass.
If the vapour density of the compound is 252, what is the molecular formula of the compound?

A compound 'X' consists of 4.8% of C and 95.2% of Br by mass. 
Name the type of chemical reaction by which X can be prepared from ethane.

Choose the correct alternative :
The gas laws which relates the volume of a gas to the number of molecules of the gas is :

The equation for the burning of octane is:

\[\ce{2C8H18 + 25O2 -> 16CO2 + 18H2O}\]

How many moles of carbon dioxide are produced when one mole of octane burns?

The equation for the burning of octane is:

\[\ce{2C8H18 + 25O2 -> 16CO2 + 18H2O}\]

What volume, at STP, is occupied by 8 moles?

The equation for the burning of octane is:

\[\ce{2C6H18 + 25O2 -> 16CO2 + 18H2O}\]

If the relative molecular mass of carbon dioxide is 44, what is the mass of carbon dioxide produced by burning two moles of octane?

The equation for the burning of octane is:

\[\ce{2C8H18 + 25O2 -> 16CO2 + 18H2O}\]

What is the empirical formula of octane?

A compound has the following percentage composition by mass: carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. Determine the empirical formula of this compound. Work correctly to 1 decimal place. (H = 1; \[\ce{C}\] = 12; \[\ce{Cl}\] = 35.5)

A compound has the following percentage composition by mass: carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. The relative molecular mass of this compound is 168, so what is its molecular formula?

A compound has the following percentage composition by mass: carbon 14.4%, hydrogen 1.2% and chlorine 84.5%. By what type of reaction could this compound be obtained from ethylene?

From the equation:

\[\ce{C + 2H2SO4 -> CO2 + 2H2O + 2SO2}\]

Calculate the mass of carbon oxidized by 49 g of sulphuric acid (C = 12, relative molecular mass of sulphuric acid = 98)

From the equation:

\[\ce{C + 2H2SO4 -> CO2 + 2H2O + 2SO2}\]

Calculate the volume of sulphur dioxide measured at STP,  liberated at the same time.

A gas cylinder of capacity of 20 dm³ is filled with gas X the mass of which is 10 g. When the same cylinder is filled with hydrogen gas at the same temperature and pressure the mass of the hydrogen is 2 g, hence the relative molecular mass of the gas is ______.

Calcium carbide is used for the artificial ripening of fruits. Actually the fruit ripens because of the heat evolved while calcium carbide reacts with the moisture. During this reaction calcium hydroxide and acetylene gas are formed. If 200 cm³ of acetylene is formed from a certain mass of calcium carbide, find the volume of oxygen required and carbon dioxide formed during the complete combustion. The combustion reaction can be represented as below.

\[\ce{2C2H2_{(g)} + 5O2_{(g)}-> 4CO2_{(g)} + 2H2O_{(g)}}\]

A gaseous compound of nitrogen and hydrogen contains 12.5%  hydrogen by mass. Find the molecular formula of the compound if its relative molecular mass is 37.

[N = 14, H = 1].

Correct the following statement :
Equal masses of all gases under identical conditions contain the same number of molecules.

Commercial sodium hydroxide weighing 30 g has some sodium chloride in it. The mixture on dissolving in water and subsequent treatment with excess silver nitrate solution formed a precipitate weighing 14.3 g. What is the percentage of sodium chloride in the commercial sample of sodium hydroxide? The equation for the reaction is

\[\ce{NaCl + AgNO3 -> AgCl + NaNO3}\]

[Relative molecular mass of NaCl = 58, AgCI = 143]

A gas cylinder contains 24 × 10²⁴ molecules of nitrogen gas. If Avogadro's number is 6 × 10²³ and the relative atomic mass of nitrogen is 14, calculate the mass of nitrogen gas in the cylinder.

A gas cylinder contains 24 × 10²⁴ molecules of nitrogen gas. If Avogadro's number is 6 × 10²³ and the relative atomic mass of nitrogen is 14, calculate the volume of nitrogen at STP in dm³.

A certain gas 'X' occupies a volume of 100 cm³ at S.T.P. and weighs 0.5 g. Find its relative molecular mass.

LPG stands for liquefied petroleum gas. Varieties of LPG are marketed including a mixture of propane (60%) and butane (40%). If 10 litres of this mixture is burnt, find the total volume of carbon dioxide gas added to the atmosphere. Combustion reaction can be represented as:

\[\ce{C3H8_{(g)} + 5O2_{(g)} -> 3CO2_{(g)} + 4H2O_{(g)}}\]

\[\ce{2C4H10_{(g)} + 13O2_{(g)} -> 8CO2_{(g)} + 10H2O_{(g)}}\]

Calculate the percentage of nitrogen and oxygen in ammonium nitrate. [Relative molecular mass of ammonium nitrate is 80, H = 1, N = 14, O = 16].

4.5 moles of calcium carbonate are reacted with dilute hydrochloric acid.

1. Write the equation for the reaction.
2. What is the mass of 4.5 moles of calcium carbonate? (Relative molecular mass of calcium carbonate is 100).
3. What is the volume of carbon dioxide liberated at STP?
4. What mass of calcium chloride is formed? (Relative molecular mass of calcium chloride is 111).
5. How many moles of HCl are used in this reaction?

Calculate the volume of 320g of SO₂ at STP .
(Atomic mass : S = 32 and O = 16)

State Gay-Lussac's law of combining volumes.

Calculate the volume of oxygen required for the complete combustion of 8.8 g of propane (C₃H₅).
(Atomic mass: C = 14, O = 16, H = 1, Molar Volume = 22.4 dm³ at STP.)

An organic compound with vapour density = 94 contains C = 12.67%, H = 2.13% and Br = 85.11%. Find the molecule formula.

[Atomic mass: C = 12, H = 1, Br = 80]

Calculate the mass of 10²² atoms of sulphur.

[Atomic mass: S = 32, C = 12 and O = 16 and Avogadro's number = 6 × 10²³]

Calculate the mass of 0.1 mole of carbon dioxide.

[Atomic mass: S = 32, C = 12 and O = 16 and Avogadro's number = 6 × 10²³]

O₂ is evolved by heating KCIO₃ using MnO₂ as a catalyst.
\[\ce{2KCI3 ->[MnO2] 2KCl + 3O2}\]

1. Calculate the mass of KClO₃ required to produce 6.72 litres of O₂ at STP. [atomic masses of K = 39, Cl = 35.5, O = 16].
2. Calculate the number of moles of oxygen present in the above volume and also the number of molecules.
3. Calculate the volume occupied by 0.01 mole of CO₂ at STP.

Solve the following:

What volume of oxygen is required to burn completely 90 dm³ of butane under similar conditions of temperature and pressure?

\[\ce{2C4H10 + 13O2 -> 8CO2 + 10H2O}\]

Solve the following:

The vapour density of a gas is 8. What would be the volume occupied by 24.0 of the gas at STP?

Solve the following:

A vessel contains X number of molecules of hydrogen gas at a certain temperature and pressure. How many molecules of nitrogen gas would be present in the same vessel under the same conditions of temperature and pressure?

Oxygen oxidase ethyne to carbon dioxide and water as shown by the equation :
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
What volume of ethylene gas at STP is required to produce 8.4 dm³ of carbon dioxide at STP?

A compound made up of two elements X and Y has an empirical formula X2Y. if the atomic weight of X is 10 and that Y is 5 and the compound has a vapour density (V.D.) 25, find its molecular formula.

Give one word or phrase for the following:

The ratio of the mass of a certain volume of gas to the mass of an equal volume of hydrogen under the same conditions of temperature and pressure.

Give one word or phrase for the following:

Formation of ions from molecules.

State Avogadro's Law

A cylinder contains 68g of ammonia gas at STP

1. What is the volume occupied by this gas?
2. How many moles of ammonia are present in the cylinder?
3. How many molecules of ammonia are present in the cylinder? [N - 14, H - 1]

Which of the following would weight the least?
[Atomic masses : Ag = 108, N - 14, O = 16,C = 12]

Complete the following calculations. Show working for complete credit :
Calculate the mass of calcium that will contain the same number of atoms as are present in 3.2 gm of Sulphur. [Atomic masses : S = 32, Ca = 40]

Complete the following calculations. Show working for complete credit :
If 6 litres of hydrogen and 4 litres of chlorine are mixed and exploded and if water is added to the gases formed, find the volume of the residual gas.

Complete the following calculations. Show working for complete credit :
 If the empirical formula of a compound is CH and it has a vapour density of 13, find the molecular formula of the compound.

Consider the following reaction and based on the reaction answer the questions that follow :
\[\ce{(NH4)2Cr2O7 ->[heat] N2(g) + 4H2O(g) + Cr2O3}\] 
Calculate :
(i) The quantity in moles of (NH₄)₂Cr₂O₇ if 63 gm of (NH₄)₂Cr₂O₇ is heated.
(ii) The quantity in moles of nitrogen formed.
(iii) The volume in litres or dm³ of N₂evolved at STP.
(iv) The mass in grams of Cr₂O₃ formed at the same time
[Atomic masses : H = 1, Cr=52, N=14]

A gas cylinder contain 12 × 10²⁴ molecules of oxygen gas
If Avogadro's number is 6 × 10²³,
calculate :
(i) The mass of oxygen present in the cylinder.
(ii) The volume of oxygen at STP present in the Cylinder[O=16]

A gaseous hydrocarbon contains 82.76% of carbon. Given that its vapour density is 29, find its molecular formula.
[C = 12, H = 1]

The equation 4NH₃5O₂ → 4NO + 6H₂O represents the catalytic oxidation of ammonia. If 100 cm³of ammonia is used, calculate the volume of oxygen required to oxidise the ammonia completely.

A gas of 32 g mass has a volume of 20 litres at STP. Calculate the gram molecular weight of the gas.

How much calcium oxide is formed when 82g of calcium nitrate is heated? Also find the volume of nitrogen dioxide evolved:
2Ca(NO₃)₂→ 2CaO + 4NO₂ + O₂ (Ca = 40,N = 14, O = 16)

The ratio between the number of molecules in 2g of hydrogen and 32 g of oxygen is
[Given that H=1,O=16]

Calculate the number of gram atoms in 4.6 grams of sodium (Na = 23)

Calculate the percentage of water of crystallization in CuSO_4. 5H₂O
(H = 1, O = 16, S = 32, Cu = 64)

A compound of X and Y has the empirical formula XY₂. Its vapour density is equal to its empirical formula weight. Determine its molecular formula.

Propane burns in air according to the following equation:

\[\ce{C3H8 + 5O2 -> 3CO2 + 4H2O}\]

What volume of propane is consumed on using 1000 cm³ of air, considering only 20% of air contains oxygen?

The mass of 11.2 litres of a certain gas at s.t.p is 24 g. Find gram molecular mass of the gas

A gas cylinder can hold 1 kg of hydrogen at room temperature and pressure.
(a) Find the number of moles of hydrogen present
(b) What weight of CO₂can the cylinder hold under similar conditions of temperature and pressure? (H = 1 C = 12, O = 16)
(c) If the number of molecules of hydrogen in the cylinder is X, calculate the number of CO₂ molecules in the cylinder with the same conditions of temperature and pressure.
(d) State the law that helped you to arrive at the above result.