Tag: drying and dehydrating agents

Questions Related to drying and dehydrating agents

Which of the following salt gets hydrolyzed in aqueous solution? 

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. A salt of weak acid and weak base

  2. A salt of strong acid and weak base

  3. A salt of weak acid and strong base

  4. All of the above

Show answer
Correct Option: D
Explanation:
Salts, when placed in water, will often react with the water to produce $H _{3}O^+$ or $OH^-$.This is known as a hydrolysis reaction.
A salt can be made of either a weak acid and strong base(i.e., basic salt), strong acid and weak base(i.e., acid salt), or a weak acid and weak base(i.e., either neutral, acidic or basic) gets hydrolyzed in aqueous solution.

A solution of sodium chloride will:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. turn red litmus blue

  2. turn blue litmus red

  3. turn red litmus orange

  4. not change the colour of either red or blue litmus

Show answer
Correct Option: D
Explanation:

Litmus paper can be used as an indicator to know whether a given substance is acidic, basic or neutral in nature.

Acidic substances turn blue litmus paper red but they have no effect on the red litmus paper.
Basic substances turn red litmus paper blue but have no effect on the blue litmus paper.
On the other hand, neutral substances have no effect on the blue as well as the red litmus paper.
Hence, the correct answer is option (D).

All  salts  are:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. strong electrolytes

  2. weak electrolytes

  3. non electrolytes

  4. either weak or strong electrolyte

Show answer
Correct Option: A
Explanation:
As, substances that give ions when dissolved in water are called $electrolytes$.They can be divided into acids, bases and salts, because they all give ions when dissolve in water. 
$Strong$ $electrolytes$ completely ionize when dissolve in water, and no neutral molecules are formed in solution.
Example - $NaCl$, $HNO _{3}$ etc.

As we know, chemically, a salt is an ionic compound as it is composed of two oppositely charged ions - cation and anion. Due to the presence of ions, they are good conductors of heat and electricity in a molten state and in solutions.
So, all salts are strong electrolytes as they completely dissolve in water and dissociates into their component ions.

Hence, option $A$ is correct.

The loss of water of crystallization to the atmosphere by a compound is termed:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. deliquescence

  2. dehydration

  3. efflorescence

  4. hydrolysis

Show answer
Correct Option: C
Explanation:

Efflorescence, spontaneous loss of water by a hydrated salt,  which occurs when the aqueous vapor pressure of the hydrate is greater than the partial pressure of the water vapour in the air. 

An aqueous solution of a salt of a weak base and a strong acid is acidic, because of:

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. electrolysis

  2. hydrolysis

  3. dissociation

  4. none of these

Show answer
Correct Option: B
Explanation:

In neutralization reaction weak base reacts with strong acid to give salt of strong acidic solution and water.

${ NH } _{ 4 }OH+{ H } _{ 2 }{ SO } _{ 4 }\rightarrow \left( { NH } _{ 4 } \right) _{ 2 }{ SO } _{ 4 }+{ H } _{ 2 }O$

Aqueous solution of which of the following salts turns the red litmus blue?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $Na _2CO _3$

  2. $NaHCO _3$

  3. $Na _2CO _3\cdot 10H _2O$

  4. All of these

Show answer
Correct Option: D
Explanation:

Sodium carbonate and sodium bicarbonate are basic salts which turn red litmus blue as they are alkaline in nature having pH more than 7.

A salt is a general name given to the chemical produced during _______ reaction between an acid and a base

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. decomposition

  2. neutralization

  3. displacement

  4. double decomposition

Show answer
Correct Option: B
Explanation:

A salt is a general name given to the chemical produced during the neutralization reaction between an acid and a base.

Sea water contains about 24g of salts dissolved per litre of it.

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. True

  2. False

Show answer
Correct Option: B
Explanation:

Approximately for every litre of seawater there is $35$ $g$ of salt.

Salts are naturally found in seawater and salts are formed in the neutralization reaction.

Which of the following are efflorescent substances?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $Cu{SO} _{4}.5{H} _{2}O$

  2. ${Na} _{2}{CO} _{3}.10{H} _{2}O$

  3. ${K} _{2}{SO} _{4}.{Al} _{2}{({SO} _{4})} _{3}.24{H} _{2}O$

  4. ${({NH} _{4})} _{2}{SO} _{4}$

Show answer
Correct Option: A,B
Explanation:

An efflorescent substance is a chemical which has water associated with its molecules, and which, when exposed to air, loses this water through evaporation. An example of an efflorescent substance is the common copper(II) sulfate crystal $(CuSO _4.5H _2O)$, a blue crystalline solid that when exposed to air, slowly loses water of crystallization from its surface to crystallize to form a white layer of anhydrous copper(II) sulfate.


$Na _2CO _3.10H _2O$ loses 9 water molecules first and then becomes completely anhydrous. 

${K} _{2}{SO} _{4}.{Al} _{2}{({SO} _{4})} _{3}.24{H} _{2}O$ is not an efflorescent as its crystals do not lose water of crystallization by efflorescence nor it is oxidised in the air. ${({NH} _{4})} _{2}{SO} _{4}$ do not has associated water molecules.

Which of the following is deliquescent?

chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $ZnCl _2$

  2. $Hg _2Cl _2$

  3. $HgCl _2$

  4. $CdCl _2$

Show answer
Correct Option: A
Explanation:

$(A)$  $ZnCl _{2}$


$Reason$ : Zinc chloride is a chemical compound with the formula $ZnCl _{2}$ and its hydrates.All zinc chlorides are colourless or white and highly soluble in water.Zinc chloride or $ZnCl _{2}$ is a $deliquescent$ salt  and forms acidic solutions in polar organic solvents,such as water, ether and acetone etc.
As we know, $deliquescent$ substances are the water soluble substances which absorbs moisture from the air and then dissolve in the absorbed moisture to change into liquid state and this phenomenon is called $deliquescence$.$ZnCl _{2}$ is one of the example of $deliquescent$ substance.