MEDIUM

Earn 100

6.2 g of a sample containing Na₂CO₃, NaHCO₃ and non - volatile inert impurity on gentle heating loses 5% of its weight due to reaction 2NaHCO₃ $⟶$ Na₂CO₃ + H₂O + CO₂. Residue is dissolved in water and formed 100 mL solution and its 10 mL portion requires 7.5 mL of 0.2 M aqueous solution of BaCl₂ for complete precipitation of carbonates.
Determine weight (in gram) of Na₂CO₃ in the original sample.

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Important Questions on Some Basic Concepts of Chemistry

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

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 $= 6 \times 10^{23}$ )

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

)

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

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

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

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:

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

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)

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

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

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

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)

MEDIUM

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 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

The minimum amount of

O_{2} (g)

consumed per gram of reactant is for the reaction:

(Given atomic mass:

F e = 56, O = 16, M g = 24, P = 31, C = 12, H = 1

)

EASY

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

The number of moles of hydrogen molecules required to produce

20

moles of ammonia through Haber’s process is:

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

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}

)

Important Questions on Some Basic Concepts of Chemistry

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