Tag: chemistry

Questions Related to chemistry

The balanced chemical reaction for the manufacturing of superphosphate is:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $Ca _3(PO _4) _2 +\ 2H _2SO _4 +\ 4H _2O \ \longrightarrow Ca(H _2PO _4) _2 \ + \ 2CaSO _4.2H _2O $

  2. $Ca _3(PO _4) _2 +\ H _2SO _4 +\ 4H _2O \ \longrightarrow Ca(H _2PO _4) _2 \ + \ CaSO _4.2H _2O $

  3. $Ca _3(PO _4) _2 +\ 2H _2SO _4 +\ 2H _2O \ \longrightarrow 2Ca(H _2PO _4) _2 \ + \ CaSO _4.2H _2O $

  4. $Ca _3(PO _4) _2 +\ 4H _2SO _4 +\ 2H _2O \ \longrightarrow Ca(H _2PO _4) _2 \ + \ 2CaSO _4.2H _2O $

Show answer
Correct Option: A
Explanation:

A well powdered phosphate rock or bone ash mixed known quantity of concentrate sulphuric acid is introduced into a cast iron chamber provided with mechanical stirrer and two valves at bottom. Each valve opens in a big chamber called den. The mixture is stirred for 2 to 5 minutes and then dumped mechanically into one of the dens through the valve. The mass is kept in the den for about 24 hours.

${ Ca } _{ 3 }{ \left( P{ O } _{ 4 } \right)  } _{ 2 }+2{ H } _{ 2 }S{ O } _{ 4 }+4{ H } _{ 2 }O\longrightarrow Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }+2CaS{ O } _{ 4 }.2{ H } _{ 2 }O+Heat$

A mixture of calcium sulphate and calcium dihydrogen phosphate is obtained .This mixture is called superphosphate.

What is the chemical formula of triple superphosphate?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $Ca(H _2PO _4).2H _2O$

  2. $Ca{(H _2PO _4)} _2.H _2O$

  3. $Ca(H _2PO _4).3H _2O$

  4. $CaSO _4.3H _2O$

Show answer
Correct Option: B
Explanation:

Triple Superphosphate is manufactured in a two stage process. First, sulphuric acid is reacted with phosphate rock, to produce phosphoric acid. Gypsum is a by-product of the stage and is removed. Secondly, the phosphoric acid is reacted with phosphate rock resulting in triple superphosphate.
Calcium superphosphate is an inorganic compound with the chemical formula $Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }$. It is commonly found as the monohydrate $Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }.{ H } _{ 2 }O$ . Both salts are colourless solids. They are used mainly as superphosphate fertilizers.

What is the other name for calcium dihydrogen phosphate?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. Superphosphate

  2. Calcium phosphorite

  3. Monocalcium phosphate

  4. none of the above

Show answer
Correct Option: C
Explanation:

Monocalcium phosphate is an inorganic compound with the chemical formula $Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }$. It is commonly found as the monohydrate $Ca{ ({ H } _{ 2 }P{ O } _{ 4 }) } _{ 2 }.{ H } _{ 2 }O$ Both salts are colourless solids. They are used mainly as superphosphate fertilizers.

Calcium phosphate used in the manufacturing of superphosphate is available in which form?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. Powdered phosphate rock

  2. Bone ash

  3. Both $A$ and $B$

  4. Liquid

Show answer
Correct Option: C
Explanation:

As a mineral resource, “phosphate rock” is defined as unprocessed ore and processed concentrates that contain some form of apatite, a group of calcium phosphate minerals that is the primary source for phosphorus in phosphate fertilizers, which are vital to agriculture.

Bone ash is a white material produced by the calcination of bones. Typical bone ash consists of about 55.82% calcium oxide, 42.39% phosphorus pentoxide, and 1.79% water. The exact composition of these compounds varies upon the type of bones being used, but generally the formula for bone ash is: ${ Ca } _{ 5 }(OH){ (P{ O } _{ 4 }) } _{ 3 }$.

What is the end product when $MgCl _2 \cdot 6H _2O$  is strongly heated?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $MgO$

  2. $MgCl _2$

  3. $Mg _2OCl _2$

  4. All of the above.

Show answer
Correct Option: A
Explanation:

When $MgCl _2 \cdot 6H _2O$  is strongly heated, the end product is $MgO$.
$MgCl _2 \cdot 6H _2O \xrightarrow {heat} MgCl _2 \cdot 2H _2O \xrightarrow {heat}  Mg _2OCl _2 \xrightarrow {heat}  MgO $
The byproducts obtained are $H _2O$, $HCl$ and $Cl _2$.

What happens when $MgCl _2 \cdot 6H _2O$ is heated?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $MgCl _2 \cdot 2H _2O$ is obtained

  2. Anhydrous $MgCl _2 $ is obtained

  3. $MgCl _2 \cdot 4H _2O$ is obtained

  4. All of the above

Show answer
Correct Option: A
Explanation:

When $MgCl _2 \cdot 6H _2O$ is heated, $MgCl _2 \cdot 4H _2O$ is obtained. Four molecules of water (per molecule of hexahydrate) are lost. This is dehydration.

Single superphosphate is preferred for phosphorus application in groundnut because it also provides:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. sulphur

  2. calcium

  3. sulphur and calcium both

  4. none of the above

Show answer
Correct Option: C
Explanation:

Phosphorus and calcium are the major nutrients limiting groundnut production,which can be obtained from SSP along with phosphorus. So, that is why is used in groundnut cultivation.

Which of the following is not a nitrogenous fertilizer?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. Ammonium sulphate

  2. Urea

  3. Ammonium nitrate

  4. Superphosphate

Show answer
Correct Option: D
Explanation:

Monocalcium phosphate is an inorganic compound with the chemical formula $Ca{ ({ H } _{ 2 }{ PO } _{ 4 }) } _{ 2 }$. It is commonly found as the monohydrate $Ca{ ({ H } _{ 2 }{ PO } _{ 4 }) } _{ 2 }.{ H } _{ 2 }O$. Both salts are colourless solids. They are used mainly as superphosphate fertilizers.

Which of the following is/are true?

some important compounds of magnesium and calcium the s-block elements chemistry

  1. $MgCl _2 \cdot 5 MgO \cdot xH _2O$ is soral magnesia

  2. Soral magnesia is a cement usd in dental filling

  3. Both of the above

  4. $MgCl _2.KCl.8H _2O$ is soral magnesia

Show answer
Correct Option: C
Explanation:

$MgCl _2 \cdot 5 MgO \cdot xH _2O$  is soral magnesia.
Soral magnesia is a cement usd in dental filling.

Single super phosphate contains:

some important compounds of magnesium and calcium the s-block elements chemistry

  1. 20% $P _2O _5$

  2. 16 to 18% $P _2O _5$

  3. 20 to 25% $P _2O _5$

  4. 10 to 46% $P _2O _5$

Show answer
Correct Option: B
Explanation:

Single superphosphate (SSP) contains 16-18% ${ P } _{ 2 }{ O } _{ 5 }$, 11-12% sulfur, and 20% calcium. SSP is manufactured by reacting rock phosphate with sulfuric acid. SSP does not have a great influence on soil pH.