Tag: drying and dehydrating agents

Questions Related to drying and dehydrating agents

$Na _2CO _3.10H _2O \longrightarrow Na _2CO _3.H _2O$

The given reaction is an example of:

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

  1. efflorescent substance

  2. deliquescent substance

  3. hygroscopic substance

  4. none of the above

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Correct Option: A
Explanation:

In this reaction water is being released. This type of substance is known as efflorescent substance.

If there are three moles of $H _2O$ for every one mole of $LiClO _4$, what is the hydrate formula?

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

  1. $\displaystyle LiClO _4 \cdot 3H _2O $

  2. $\displaystyle 3LiClO _4 \cdot 3H _2O $

  3. $\displaystyle 3LiClO _4 \cdot H _2O $

  4. $\displaystyle LiClO _4 \cdot (H _2O) _3 $

  5. $\displaystyle 3(LiClO _4) \cdot 3(H _2O) _3 $

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Correct Option: A
Explanation:

If there are three moles of $H _2O$ for every one mole of $\displaystyle LiClO _4$. The hydrate formula would be $\displaystyle LiClO _4 \cdot 3H _2O $

$Cu(s)+HNO _3(aq)\rightarrow Cu(NO _3) _2(aq)+H _2O(l)+NO(g)$ 

If $Cu(NO _3) _2$ goes into solution as ions, find the number of ions into which it will dissociate?

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

  1. $1$

  2. $2$

  3. $3$

  4. $4$

  5. $5$

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Correct Option: C

 A student is performing an experiment where a blue salt is being heated to dryness in order to determine the percent of water in the salt. Which pieces of laboratory equipment would be used to help determine this percentage?
 i. A crucible and cover
 ii. Tongs
iii. A triple beam balance 

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

  1. ii only

  2. iii only

  3. i and iii only

  4. ii and iii only

  5. i. ii and iii

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Correct Option: E
Explanation:

In this experiment, a known mass of hydrated copper(II) sulfate is heated to remove the water of crystallization and then weigh into it between 2 g and 3 g of hydrated copper(II) sulphate.A deep blue copper compound is made white through the addition of heat.So the apparatus needed is crucible,cover,tongs and triple beam balance.

Find the substances which dissociate completely when placed into excess amounts of distilled water? 
chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. $C _2H _5OH$

  2. $HCOOH$

  3. $LiNO _3$

  4. $Mg(OH) _2$

  5. All of the above

Show answer
Correct Option: C
Explanation:

Lithium nitrate, $\displaystyle LiNO _3$  dissociates completely when placed into excess amounts of distilled water.
It is a strong electrolyte.
$\displaystyle LiNO _3 \rightarrow Li^+  +  NO _3^-$

The type of bonding present in a substance can be determined from experimental data.
Based on the information in the table below, which of the following substances is MOST likely to represent the identity of the solid?

Melting Point Density Conductivity Conductivity in Aqueous Solution
$801^{\circ}C$ $2.17\ g/cc$ None Excellent
chemistry water drying and dehydrating agents hydrolysis of salts and the ph of their solutions chemical equilibrium and acids-bases

  1. Platinum, $Pt$

  2. Sodium chloride, $NaCl$

  3. Glucose, $C _{6}H _{12}O _{6}$

  4. Quartz, $SiO _{2}$

Show answer
Correct Option: B
Explanation:

$(B)$  Sodium chloride, $NaCl$


$Reason$ : Sodium chloride is an ionic compound with the chemical formula $NaCl$, in which sodium(cation) $Na^{+}$ and chloride(anion) $Cl^{-}$ ions are in the ratio $ 1 : 1 $.It is commonly known as table salt, common salt or halite. Seawater is the major source of this salt.
Some properties of sodium chloride are as follows - 
$1)$ It is easily soluble in water and partially or insoluble in other liquids.
$2)$ They are white crystals with a desity of $2.17 g/cc$, which do not have an odor but possess a taste.
$3)$ In its aqueous state $NaCl$ acts as a good conductor of electricity due to the free movement of ions.
$4)$ It has a melting point of $801^{o} C$ and a boilng point of $1,413 ^{o} C$.
$Uses$ :
$1)$ This salt is used in glass production.
$2)$ It is widely used in food industries as a food preservative and as a flavour enhancer.

Identify the correct representation of reaction occurring during chloralkali process.

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

  1. $2NaCl(l) + 2H _{2}O(l) \rightarrow   2NaOH(l) + Cl _{2}(g) + H _{2}(g)$

  2. $2NaCl(aq) + 2H _{2}O(aq) \rightarrow 2NaOH(aq) + Cl _{2}(g) + H _{2}(g)$

  3. $2NaCl(aq) + 2H _{2}O(l)\rightarrow  2NaOH(aq) + Cl _{2}(aq) + H _{2}(aq)$

  4. $2NaCl (aq) + 2H _{2}O (l)\rightarrow   2NaOH (aq) + Cl _{2}(g) + H _{2}(g)$

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Correct Option: D
Explanation:

Sodium chloride in water is a brine solution which gives sodium hydroxide in aqueous solution and hydrogen and chlorine gases. It is known as chloralkali process. It is an industrial process for the electyrolysis of sodium chloride. It is the technology which is used to produce chlorine and caustic soda(sodium hydroxide) on commercial scale.

Which hydrolysis results in basic solution?

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

  1. Neutralisation reaction

  2. Weak acid

  3. Strong acid

  4. Weak base

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Correct Option: B
Explanation:

Base hydrolysis results in basic solution.

A base hydrolysis reaction will resemble the reaction for base dissociation. A common weak base that dissociates in water is ammonia:

$NH _3 + H _2O \rightarrow NH^{4+} + OH^-$

In the hydrolysis of ammonia, the ammonia molecule accepts a proton from the water (because water acts as a Bronsted-Lowry acid), producing a hydroxide anion ($OH^-$). Similar to a basic dissociation reaction, ammonia forms ammonium and a hydroxide from the addition a water molecule. 

State True or False.
$NH _{4}Cl$ when dissolved in water undergoes anionic hydrolysis.

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

  1. True

  2. False

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Correct Option: B
Explanation:

$NH _4Cl $ when dissolved in water undergoes cationic hydrolysis as follows: 
$NH _4Cl $ $\rightarrow $ $NH _4 ^+ + Cl^- $
Ammonium ion being a strong acid takes $OH^- $ ions furnished by water as : 
$NH _4^+ + H _2O \rightarrow NH _4OH\  (freely\  ionized) + H^+ $
Thus concentration of $OH^-$ ions decreases and that of $H^+ $ ion increases due to cationic hydrolysis and consequently the solution become acidic in nature. 

Which of the following substances can be used for drying gases?

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

  1. Calcium carbonate

  2. Sodium carbonate

  3. Sodium bicarbonate

  4. Calcium oxide

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Correct Option: D
Explanation:

Calcium oxide $(CaO)$ absorbs moisture and hence, can be used for drying gases.