Tag: acids, bases and salts

Questions Related to acids, bases and salts

What additional factors affect the rate of dissolution of ionic solids like salts?

salts salts and their classification acids, bases and salts chemistry

  1. Enthalpy and entropy

  2. Enthalpy and surface area

  3. Entropy and temperature

  4. Enthalpy and temperature

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Correct Option: D
Explanation:

Enthalpy and temperature affect the rate of dissolution of ionic solids like salts.
Positive value of enthalpy change indicates that the dissolution of ionic salt is endothermic. Increasing temperature will increase the dissolution of ionic solids like salts.

On the other hand,
negative value of enthalpy change indicates that the dissolution of ionic salt is exothermic. Increasing temperature will decrease the dissolution of ionic solids like salts.
Hence, option (D) is the correct answer.

What are the products of the following reaction? 

$\displaystyle { H } _{ 2 }{ SO } _{ 4 }\left( aq \right) +{ Ba\left( OH \right)  } _{ 2 }\rightarrow $

salts salts and their classification acids, bases and salts chemistry

  1. $\displaystyle { O } _{ 2 }$

  2. $\displaystyle Ba{ SO } _{ 4 }$

  3. $\displaystyle { O } _{ 2 }$ and $\displaystyle Ba{ SO } _{ 4 }$

  4. $\displaystyle { H } _{ 2 }O$ and $\displaystyle Ba{ SO } _{ 4 }$

  5. None of these

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Correct Option: D
Explanation:

The products of the  reaction between barium hydroxide and sulphuric acid are barium sulphate and water.
$\displaystyle { H } _{ 2 }{ SO } _{ 4 }\left( aq \right) +{ Ba\left( OH \right)  } _{ 2 }\rightarrow \displaystyle Ba{ SO } _{ 4 } + \displaystyle { H } _{ 2 }O    $
It is acid base neutralisation reaction to form salt and water.

What is a titration curve?

salts salts and their classification acids, bases and salts chemistry

  1. A graph of volume vs. pH for a titration.

  2. A graph of acid vs. base for a titration.

  3. A graph of acid vs. pH for a titration.

  4. A graph of volume vs. acid for a titration.

  5. A graph of base vs. pH for a titration.

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Correct Option: A
Explanation:

A titration curve is a graph of volume of added base (or acid) vs. pH for a titration.

What is titration?

salts salts and their classification acids, bases and salts chemistry

  1. A technique used to analyze properties of solutions. It involves adding a titrant to the solution to be analyzed.

  2. A way to determine the concentration of an acid but not a base.

  3. A way to perform neutralization reactions.

  4. A way to determine the concentration of a base but not an acid.

Show answer
Correct Option: A
Explanation:

Titration is a technique used to analyze properties of solutions (concentrations). It involves adding a titrant to the solution to be analyzed.
The process of adding one solution from the burette to another in the conical flask in order to complete the chemical reaction between the two solutions is known as titration. Of two solutions, one must be standard (of known concentration) and other must be of unknown strength.

Among the following reactions, find the one which gives precipitation?

salts salts and their classification acids, bases and salts chemistry

  1. $\displaystyle { Ag }^{ + }\left( aq \right) +{ Cl }^{ - }\rightarrow AgCl\left( s \right) $

  2. $\displaystyle { C } _{ 5 }{ H } _{ 12 }\left( s \right) +8{ O } _{ 2 }\left( g \right) \rightarrow 5{ CO } _{ 2 }\left( g \right) +6{ H } _{ 2 }O\left( l \right) $

  3. $\displaystyle { NH } _{ 3 }\left( s \right) +{ H } _{ 2 }O\left( s \right) \leftrightharpoons { NH } _{ 4 }^{ + }\left( s \right) +{ OH }^{ - }\left( s \right) $

  4. $\displaystyle H{ C } _{ 2 }{ H } _{ 3 }{ O } _{ 2 }\left( l \right) +{ OH }^{ - }\left( aq \right) \rightarrow { H } _{ 2 }O\left( l \right) +{ C } _{ 2 }{ H } _{ 3 }{ O } _{ 2 }^{ - }\left( aq \right) $

  5. $\displaystyle Ca{ CO } _{ 3 }\left( s \right) \rightarrow CaO\left( s \right) +Ca{ O } _{ 2 }\left( g \right) $

Show answer
Correct Option: A
Explanation:

$A.$ Precipitation reaction
A precipitate of $AgCl$ is formed.
$\displaystyle { Ag }^{ + }\left( aq \right) +{ Cl }^{ - }\rightarrow AgCl\left( s \right) $
$B.$ Combustion reaction
$C.$ Hydrolysis
$D.$ Acid-base neutralization-Acetic acid is neutralized by hydroxide base.
$E.$ Decomposition reaction

How do you determine the concentration of the unknown substance from the titration data?

salts salts and their classification acids, bases and salts chemistry

  1. $(cH^+)(VH^+) = (cOH^-)(VOH^-)$

  2. $(cH^+)(VH^+) / (cOH^-)(VOH^-) = 1$

  3. $(cH^+)(VH^+) / (cOH^-)(VOH^-) = -log:( pH)$

  4. $-log (cH^+)(VH^+) = pH$

Show answer
Correct Option: A
Explanation:

You determine the concentration of the unknown substance from the titration data by using the following equation
$\displaystyle  (cH^+)(VH^+) = (cOH^-)(VOH^-)$
$\displaystyle  (cH^+)  $  represents hydrogen ion concentration or acid concentration.
$\displaystyle   (VH^+) $ represents volume of acid solution.
$\displaystyle   (cOH^-)  $  represents hydroxide ion concentration (or base solution concentration).
$\displaystyle   (VOH^-)$  represents volume of base solution.

What is the state of a precipitated compound?

salts salts and their classification acids, bases and salts chemistry

  1. $(l)$

  2. $(g)$

  3. $(aq)$

  4. $(s)$

Show answer
Correct Option: D
Explanation:

Precipitation is the formation of solid from a solution. When the reaction occurs in a liquid solution, the solid formed is called the 'precipitate'. The chemical that causes the solid to form is called the 'precipitant'.

Which type of reaction produces precipitates which are ionic compounds?

salts salts and their classification acids, bases and salts chemistry

  1. Decomposition

  2. Double Replacement

  3. Synthesis

  4. Single Replacement

Show answer
Correct Option: B
Explanation:

Double replacement reactions, also called as double displacement, exchange or metathesis reactions occur when parts of ionic compounds are exchanged, making two new compounds.

However, if during this reaction, a product is formed such that it is insoluble in water then it leads to precipitation of the product. There is a formation of an insoluble mass at the bottom of the test tube which is known as the precipitate. 
An example of the double replacement reaction where an ionic compound is precipitated is:-
$BaCl _2+Na _2SO _4 \rightarrow BaSO _4+2NaCl$
Here, $BaSO _4$ is an ionic product that forms an insoluble white mass as it is insoluble in water.
Hence, the correct answer is the option (B).

The "alum" used in cooking is potassium aluminum sulfate hydrate, $KAl(SO _{3}) _{2}\cdot xH _{2}O$. To find the value of x, a sample of the compound is heated. The mass of the empty crucible is $20.01\ g$.
The alum hydrate was added to the crucible until the total mass of the crucible and hydrate was $24.75\ g$. The sample was heated in the crucible until the final mass of the crucible and anhydrous product was $22.5\ g$.
What is the value of x?

salts salts and their classification acids, bases and salts chemistry

  1. $2$

  2. $3$

  3. $12$

  4. $18$

Show answer
Correct Option: C
Explanation:

Mass of crucible Hydrate $=24.75$

Mass of hydrate $=24.75-20.01=4.74$ $g$
Mass of anhydrate $=22.5-20.01=2.49$ $g$
$KAl(SO _3) _2\cdot xH _2O\longrightarrow KAl(SO _3) _2+xH _2O$
Mass: $(18x+226)$ $g$          Mass $=226$ $g$
$(226+18x)$ $g$ $\overset {gives}{\longrightarrow}$ $226$ $g$
$4.74$ $g$ $\overset {gives}{\longrightarrow}$ $2.49$ $g$
$\cfrac{226+18x}{4.74g}=\cfrac{226}{2.49}$
$x\approx 12$

According to Lewis theory, neutralisation is the :

salts salts and their classification acids, bases and salts chemistry

  1. transfer of proton from acid to base

  2. transfer of proton from base to acid

  3. transfer to electron pair from acid to base

  4. transfer of electron pair from base to acid

Show answer
Correct Option: D
Explanation:

According to Lewis theory, neutralization is the transfer of electron pair from base to acid.