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MnO₂ on ignition converts into Mn₃O₄ . A sample of pyrolusite having 75% MnO₂, 20% inert impurities and rest water is ignited in air to constant weight. What is the percentage of Mn in the ignited sample ?

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Important Questions on Some Basic Concepts of Chemistry

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

1

gram of a carbonate

(M_{2} {CO}_{3})

on treatment with excess

HCl

produces

0.01186

moles of

{CO}_{2}

. The molar mass of

M_{2} {CO}_{3}

{gmol}^{- 1}

is:

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

What is the mass of the precipitate formed when 50 mL of

16.9 %

solution of

A g N O_{3}

is mixed with 50 mL of

5.8 %

NaCl solution?

(Ag = 107.8, N = 14, O = 16, Na = 23, Cl = 35.5)

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

In the following reaction:

$A + 2 B + 3 C ⇌ A B_{2} C_{3}$
$6.0 g$ of $A$ , $6.0 \times 10^{23}$ atoms of $B$ and $0.036 mol$ of $C$ reacted and formed $4.8 g$ of compound $A B_{2} C_{3}$ . If the atomic mass of $A$ and $C$ are $60$ and $80 amu$ , respectively. What is the atomic mass of $B$ in $amu$ ? (Avogadro number $= 6 \times 10^{23}$ )

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

When 262 g of xenon (atomic mass = 131) reacted completely with 152 g of fluoride (atomic mass = 19), a mixture of

X e F_{2}

and

X e F_{6}

was produced. The molar ratio of

X e F_{2} : X e F_{6}

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

For the following reaction, the mass of water produced from

445 g

C_{57} H_{110} O_{6}

is:

2 C_{57} H_{110} O_{6} (s) + 163 O_{2} (g) \to 114 {CO}_{2} (g) + 110 H_{2} O (l)

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

The amount of metallic

Zn

(Atomic weight

= 65.4

) required to react with aqueous sodium hydroxide to produce

1 g

H_{2}

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

A gaseous hydrocarbon on combustion gives $0.72 g$ of water and $3.08 g$ ${CO}_{2}$ . What is the empirical formula of the hydrocarbon?

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

300 K

and

1 atm

15 mL

of a gaseous hydrocarbon requires

375 mL

air containing

20 % O_{2}

by volume, for complete combustion. After combustion, the gases occupy

345 mL

. Assuming that the water formed is in liquid form and the volumes were measured at the same temperature and pressure, the formula of the hydrocarbon is:
(Assume complete combustion of reactant)

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time, the passage of air is stopped, but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$ ) of $Pb$ produced per $kg$ of $O_{2}$ consumed is ____. (Atomic weights in $g {mol}^{- 1} : O = 16, S = 32, Pb = 207$ )

Give the answer to the nearest integer value.

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

The ammonia is prepared by treating ammonium sulphate with calcium hydroxide is completely used by ${NiCl}_{2} \cdot 6 H_{2} O$ to form a stable coordination compound. Assume that, both the reactions are $100 %$ completed. If $1584 g$ of ammonium sulphate and $952 g$ of ${NiCl}_{2} \cdot 6 H_{2} O$ are used in the preparation, the combined weight (in grams) of gypsum and the nickel ammonia coordination compound produced is ____.

Atomic weights in $g {mol}^{- 1}$ :

$H = 1; N = 14 O = 16; S = 32 Cl = 35 .5; Ca = 40 Ni = 59$

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

When 22.4 L of

C_{4} H_{8}

at STP is burnt completely, 89.6 L of

C O_{2}

gas at STP and 72 g of water are produced.
The volume of the oxygen gas at STP consumed in the reaction is closest to

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

The molecular formula of a commercial resin used for exchanging ions in water softening is

C_{8} H_{7} S O_{3} N a

(molecular weight = 206)

. What would be the maximum uptake of

C a^{2 +}

ions by the resin if expressed in

mol

per

gm

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

LiOH

reacts with

{CO}_{2}

to form

{Li}_{2} {CO}_{3}

(atomic mass of

Li = 7

). The amount of

{CO}_{2}

(in g) consumed by

1 g

LiOH

is closest to

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

What is the quantity of hydrogen gas liberated when

46 g

sodium reacts with excess ethanol? (Given Atomic mass of

Na = 23 g

)

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

Excess of

NaOH (aq)

was added to

100 mL

{FeCl}_{3} (aq)

resulting into

2.14 g

Fe {(OH)}_{3}

. The molarity of

{FeCl}_{3} (aq)

is:

(Given the molar mass of

Fe = 56 g

{mol}^{- 1}

and molar mass of

Cl = 35 .5 g {mol}^{- 1}

)

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

5 L

of an alkane requires

25 L

of oxygen for its complete combustion. If all volumes are measured at constant temperature and pressure, the alkane is

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

The amount of arsenic pentasulphide that can be obtained when

35.5 g

arsenic acid is treated with excess

H_{2} S

in the presence of conc.

HCl

(assuming

100 %

conversion) is

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

20.0 g of a magnesium carbonate sample decomposes on heating to give carbon dioxide and 8.0 g magnesium oxide. What will be the percentage purity of magnesium carbonate in the sample?

(Atomic weight: Mg = 24)

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

A mixture of

100 m mol

Ca {(OH)}_{2}

and

2 g

of sodium sulphate was dissolved in water and the volume was made up to

100 mL .

What is the mass of calcium sulphate formed and the concentration of

{OH}^{-}

in resulting solution, respectively? (Molar mass of

Ca {(OH)}_{2}, {Na}_{2} {SO}_{4}

and

{CaSO}_{4}

are

74, 143

and

136 g {mol}^{- 1},

respectively;

K_{sp}

Ca {(OH)}_{2} is 5 .5 \times 10^{- 6}

)

MEDIUM

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Stoichiometry and Stoichiometric Calculations

A sample of

{NaClO}_{3}

is converted by heat to

NaCl

with a loss of

0.16 g

of oxygen. The residue is dissolved in water and precipitated as

AgCl

. The mass of

AgCl

(in

g

) obtained will be: (Given: Molar mass of

AgCl = 143 .5 g {mol}^{- 1}

)

MnO2 on ignition converts into Mn3O4 . A sample of pyrolusite having 75% MnO2, 20% inert impurities and rest water is ignited in air to constant weight. What is the percentage of Mn in the ignited sample ?

Important Questions on Some Basic Concepts of Chemistry

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MnO₂ on ignition converts into Mn₃O₄ . A sample of pyrolusite having 75% MnO₂, 20% inert impurities and rest water is ignited in air to constant weight. What is the percentage of Mn in the ignited sample ?