Tag: heavy water

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Questions Related to heavy water

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

What is formed when calcium carbide reacts with heavy water?

  1. $C _{2}D _{2}$
  2. $CaD _{2}$
  3. $Ca _{2}D _{2}O$
  4. $CD _{2}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Calcium carbide reacts with ordinary water and acetylene forms, similarly calcium carbide reacts with heavy water and  deuterated acetylene $C _{2}D _{2}$ forms.
Reaction:

$CaC _2+2D _2O\rightarrow C _{2}D _{2}$ + $Ca(OD) _2$

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Some statements about heavy water are given below:
$(a):$Heavy water is used as a moderator in nuclear reactions
$(b):$Heavy water is more associated than ordinary water
$(c):$Heavy water is more effective solvent than ordinary water
Select correct statements:

  1. $(a),\:(b)\:and\:(c)$
  2. $(b)\:and\:(c)$
  3. $(a)\:and\:(c)$
  4. $(a)\:and\:(b)$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Heavy water is $D _2O$, it has higher molar mass than water.
It is used in nuclear reactors, where it acts as a neutron moderator to slow down neutrons so that they are more likely to react with the fissile uranium-235 than with uranium-238, which captures neutrons without fissioning.
Also, dielectric constant of $D _2O$ is lower than water so solubility of inorganic substances is greater in$H _{2}O$ than $D _{2}O$.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Of the two solvent ${ H } _{ 2 }O$ and ${ D } _{ 2 }O$, $NaCl$ dissolves:

  1. equally in both solvents
  2. only in ${ H } _{ 2 }O$ but remains insoluble in ${ D } _{ 2 }O$
  3. more in ${ D } _{ 2 }O$
  4. more in ${ H } _{ 2 }O$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

$NaCl$ (and other ionic compounds) dissolve more in $H _2O$ than in $D _2O$ as the dielectric constant of $H _2O$ $(78.39)$ is higher than the dielectric constant of $D _2O:(78.06)$. This is due to lower molar mass of $H _2O$ as compared to that of $D _2O$.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Which of the following is not the possible enol form of propanone in the presence of heavy water?

  1. ${ CH } _{ 3 }-CD=\overset { \overset { OD }{ | } }{ C } -D$
  2. ${ CH } _{ 3 }-\overset { \overset { OD }{ | } }{ C= } CHD$
  3. ${ CH } _{ 2 }=\overset { \overset { OD }{ | } }{ C- } { CD } _{ 3 }$
  4. ${ CD } _{ 2 }=\overset { \overset { OD }{ | } }{ C- } { CD } _{ 3 }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the presence of D2O, the alpha-hydrogens of propanone are replaced by deuterium through keto-enol tautomerism. Option A shows a structure that is not a standard enol form of propanone as it implies incorrect substitution patterns or connectivity for the enolization of propanone.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Which one of the following statements is correct about $D _{2}O$ and $H _{2}O$?

  1. $D _{2}O$ has lower dielectric constant than $H _{2}O$
  2. $NaCl$ is more soluble in $D _{2}O$ than in $H _{2}O$

  3. Both (a) and (b) are correct

  4. None of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

D2O has a lower dielectric constant than H2O, which affects the solubility of ionic compounds. Consequently, many ionic salts, including NaCl, are less soluble in D2O than in H2O.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

Which one of the following processes will produce hard water?

  1. Saturation of water with $CaCO _3$
  2. Addition of $Na _2SO _4$ to water.
  3. Saturation of water with $MgCO _3$
  4. Saturation of water with $CaSO _4$
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of calcium and magnesium-containing minerals such as limestone, chalk and dolomite.
The following processes will produce hard water
1. saturation of water with $CaCO _3$
2. saturation of water with $MgCO _3$
3. saturation of water with $CaSO _4$
Hence options A,B & D are correct.

Multiple choice chemistry hard water and soft water heavy water study of heavy water hydrogen and its compounds

$D _2O$ differ in the following except:

  1. freezing point

  2. density

  3. ionic product of water

  4. its reaction with sodium
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The freezing point of water is $0 ^oC$, whereas the freezing point of heavy water is $3.8 ^0C$. 


At $20 ^0C$, the density of water is $0.9982$ g/mL, whereas the density of heavy water is $1.1056$ g/mL. 

Similarly, water and heavy water differ in the value of the ionic product. 

However, the chemical properties (such as reaction with sodium) of water are similar to that of heavy water due to the same electronic configuration.