Tag: salts

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Multiple choice salts salts and their classification acids, bases and salts chemistry

What is the state of a precipitated compound?

  1. $(l)$
  2. $(g)$
  3. $(aq)$
  4. $(s)$
Reveal answer Fill a bubble to check yourself
D Correct answer
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'.

Multiple choice salts salts and their classification acids, bases and salts chemistry

Which type of reaction produces precipitates which are ionic compounds?

  1. Decomposition

  2. Double Replacement

  3. Synthesis

  4. Single Replacement
Reveal answer Fill a bubble to check yourself
B Correct answer
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).

Multiple choice salts salts and their classification acids, bases and salts chemistry

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?

  1. $2$
  2. $3$
  3. $12$
  4. $18$
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $=226$ $g$
$(226+18x)$ $g$ $\overset {gives}{\longrightarrow}$ $226$ $g$
$4.74$ $g$ $\overset {gives}{\longrightarrow}$ $2.49$ $g$
$\cfrac{226+18x}{4.74g}=\cfrac{226}{2.49}$
$x\approx 12$

Multiple choice salts salts and their classification acids, bases and salts chemistry

According to Lewis theory, neutralisation is the :

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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

Multiple choice salts salts and their classification acids, bases and salts chemistry

Where does the equivalence point occur on a titration curve for a strong acid/strong base titration?

  1. At the endpoint, after pH 7.

  2. At pH 7, in the middle of the dramatic slope.

  3. At the very end of titration, between pH 10-12.

  4. Before the slope increases dramatically, between pH 2 and 4.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The equivalence point occur at pH 7, in the middle of the dramatic slope,
on a titration curve for a strong acid/strong base titration.
At the equivalence point, the salt of strong acid and strong base is completely hydrolyzed which gives a neutral solution with pH 7 as hydrogen ion concentration is equal to hydroxide ion concentration.

Multiple choice salts salts and their classification acids, bases and salts chemistry

$0.1\ M\ H _2SO _4$ has the same concentration of $H^+$ ions as $0.1 N HCl$.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

0.05 M $\displaystyle H _2SO _4$  has the same concentration of $\displaystyle H^+$ ions as 0.1 M HCl.
 0.05 M $\displaystyle   H _2SO _4$  $\displaystyle  = 2 \times 0.05 = 0.1$ M $\displaystyle H^+$ ions.
 0.1 M HCl $\displaystyle  = 0.1$ M $\displaystyle H^+$ ions.