Some important compounds of magnesium and calcium - class-XI

The gas evolved is $NH _{3}$.

In nature, calcium sulphate occurs in the form of  anhydrite $(CaSO _4)$ and gypsum $(CaSO _4 \cdot 2H _2O)$.

• A refractory material or refractory is a heat-resistant material
• Magnesium oxide is used to make linings for some furnaces. It is known as a refractory material - which just means that it is resistant to heat. You may have come across this on the CIE page about ceramics. Magnesium oxide has a high melting point (2852°C) and so resists the high temperatures in a furnace.
  

A suspension of Barium sulphate $(BaSO _4)$, a chalky powder, is ingested in to patient at the time of X-ray. Barium coated areas of the digestive tract then appear on an X-ray as white.

Heating gypsum (CaSO4.2H2O) to 120 degrees Celsius drives off 1.5 molecules of water, resulting in Plaster of Paris, which is calcium sulfate hemihydrate (CaSO4.1/2H2O).

Solubility of alkaline earth metal sulfates decreases down the group. Magnesium sulfate is highly soluble in water, making it the most stable in aqueous solution compared to the others which are less soluble or insoluble.

Gypsum is a hydrated calcium sulphate (CaSO4. 2H2O). Plaster of Paris is calcium sulphate hemihydrate. 

$\displaystyle { Mg\left( OH \right)  } _{ 2 }\rightleftharpoons M{ \underset { S }{ g }  }^{ 2+ }+2{ \underset { 2S }{ OH }  }^{ - }$
$\displaystyle { K } _{ sp }{ Mg\left( OH \right)  } _{ 2 }=\left[ { Mg }^{ 2+ } \right] { \left[ { OH }^{ - } \right]  }^{ 2 }$
$\displaystyle \Rightarrow \quad { K } _{ sp }{ Mg\left( OH \right)  } _{ 2 }=4{ S }^{ 3 }$
$\displaystyle 1.96\times { 10 }^{ -11 }=4{ S }^{ 3 }$
or $\displaystyle S={ \left[ \frac { 1.96\times { 10 }^{ -11 } }{ 4 }  \right]  }^{ 1/3 }$
or $\displaystyle S={ \left( 4.9\times { 10 }^{ -12 } \right)  }^{ 1/3 }$
$\displaystyle \therefore \quad S=1.69\times { 10 }^{ -4 }$
So, concentration of $\displaystyle \left[ { OH }^{ - } \right]=2S $
$\displaystyle \therefore \quad \left[ { OH }^{ - } \right] =3.38\times { 10 }^{ -4 }$
$\displaystyle \Rightarrow \quad pOH=-\log { \left[ { OH }^{ - } \right]  } $
$\displaystyle =-\log { \left[ 3.38\times { 10 }^{ -4 } \right]  } $
$\displaystyle \therefore \quad pOH=3.471$
$\displaystyle pH=14-pOH$
$\displaystyle =14-3.471$
$\displaystyle \therefore \quad pH=10.529$

The reaction between Mg and oxygen is as follow:

Tricalcium phosphate (TCP) is a calcium salt of phosphoric acid with the chemical formula $Ca _3(PO _4) _2$. It is also known as tribasic calcium phosphate and bone phosphate of lime (BPL). It is a white solid, with very low solubility.

The evolution of fluorine containing gases is a major problem in the SSP production process. Theese gases arise from the fluoride and silicon contained as impurities in the rock. These elements combine with the water to form flurosilic acid$ (H _2SiF _6). $ Any excess silicon dissolves (in acid) to form silicic acid $(SiO _2-H _2O).$Typical rock phosphate contains about 8% Silica and 3% Fluorine by weight.

Gypsum or Calcium Sulphate dihydrate $CaSO _4.2H _2O$ is mostly found in beds of sedimentary rocks.

Monocalcium phosphate is an inorganic compound with the formula $Ca{(H _2PO _4)} _2$. It is commonly found as the monohydrate $Ca{(H _2PO _4)} _2.H _2O$. Both salts are colourless solids. They are used mainly as water soluble superphosphate fertilisers.

Calcium sulphate can be produced from Calcium oxide by reacting it with Sulphuric acid. The reaction can be written as-
$CaO$ $+$ $H _2SO _4$ $=$ $CaSO _4$ $+$ $H _2O$

The correct formula of Epsom salt is ${ MgSO } _{ 4 }\cdot { 7H } _{ 2 }O$. 

$MgSO _4$ has 7 moles of water of hydration.
$CaSO _4$ has 2 moles of water hydration $BaSO _4$ has 1 mole of water of hydration.
Thus $MgSO _4$ has maximum x.

Anhydrous calcium sulphate, CaSO$ _4$ is known as 'dead burnt plaster'. It is formed by heating gypsum, $CaSO _4.2H _2O$ at a temperature above 393 K.

The purpose of adding gypsum is only to slow down the process of setting of the cement so that it gets sufficiently hardened.

$Mg{ SO } _{ 4 }\cdot 7{ H } _{ 2 }O$ is also known as Epsom salt.

Here answer is option C

Gypsum
is a mineral and is hydrated calcium sulphate in chemical form. Gypsum
plays a very important role in controlling the rate of hardening of the
cement. During the cement manufacturing process, upon the cooling of
clinker, a small amount of gypsum is introduced during the final
grinding process.Gypsum is added to control the “setting of cement”. If
not added, the cement will set immediately after mixing of water leaving
no time for concrete placing.
conclusion: hence the option (A) is correct

In the periodic table, on moving down, water solubility of alkaline earth metal decreases. Oxides and hydroxides of alkaline earth metal are basic except Be which is amphoteric.
Hence the metal M is Be.
conclusion: hence the option (D) is correct.

Several blocks of magnesium are fixed to the bottom of a ship to. Magnesium, on account of its lightness, great affinity for oxygen and toughness is used in ship. Being a lighter element, magnesium makes the ship lighter when it is fixed to the bottom of the ship.

Gypsum is calcium sulphate dihydrate $(CaSO _4 \cdot 2H _2O)$. Zlnorsper is not chemically similar to gypsum.

The formula of Potash magnerin is $K _{2} SO _{4} .MgSO _{4} .6H _{2} O$

When Plaster of Paris $CaSO _4.\dfrac{1}{2}H _2O$ is heated above 393 K, its water of crystallisation is lost and anhydrous Calcium sulphate is left that is known as a dead burnt plaster.

Magnesium burns in steam to produce white magnesium oxide and hydrogen gas. Very clean magnesium ribbon has a very slight reaction with cold water. After several minutes, some bubbles of hydrogen form on its surface, and the coil ofmagnesium ribbon usually floats to the surface.

Magnesium hydroxide is the inorganic compound with the chemical formula Mg(OH)₂. It occurs in nature as the mineral brucite.

Mg2C3 reacts with D2O to form propyne-d4 (CH3-C=CD). Hydroboration-oxidation adds OH and H across the triple bond, followed by reduction and dehydration, leading to the specified product structure.

Chlorophyll is a magnesium-porphyrin complex, where the central metal ion is magnesium (Mg).

Reaction:
$2Mg+CO _2\rightarrow 2MgO+C$

Beryllium is less reactive than magnesium and cannot displace magnesium from its salts. In fact, magnesium is more electropositive than beryllium.

Mixing solid MgO  with MgCl2  produces Sorrel cement

It is often encountered as the heptahydrate sulfate mineral epsomite commonly called Epsom salt${ MgSO } _{ 4 }\cdot { 7H } _{ 2 }O$. It has enormous health benefits.

The calcium compound that hardens on wetting with water is commonly known as Plaster of Paris (POP), chemically known as calcium sulphate hemihydrate having the formula $CaSO _4.1/2H _2O$

Insoluble $CaSO _4$ is formed which deposits on the surface of marble
and prevent the further action of dilute $H _2SO _4$, so the evolution
of $CO _ 2$ ceases after some time.

Burning of magnesium, it combines with atmospheric oxygen to produce $MgO$. Thus mass gets increased on combustion.

A bleaching agent is a material that lightens or whitens a substrate through chemical reaction. The bleaching reactions usually involve oxidative or reductive processes that degrade color systems In paper industry, the chemical compound used for bleaching is calcium bisulphate. 

When Calcium Phosphate is treated with Sulphuric Acid, Calcium Sulphate is obtained as a precipitate along with the formation of Phosphoric Acid. The balanced equation can be written as-
$Ca _3(PO _4) _2$ $+$ $3H _2SO _4$ $=$ $2H _3PO _4$ $+$ $3CaSO _4$

Magnesium Sulphate is produced from Magnesium carbonate by reacting the carbonate with Sulphuric acid. The balanced equation can be written as-
${MgCO} _{3}$${+}$ ${H} _{2}{SO} _{4}$  ${=}$ ${MgSO} _{4}$ ${+}$ ${CO} _{2}$ ${+}$ ${H} _{2}{O}$

The chemical formula of Gypsum is ${CaSO} _{4}$${.}$${2H} _{2}{O}$. It contains two moles of water in it. It can also be said as Calcium Sulphate dihydrate.

Gypsum or Calcium sulphate can be produced from Zinc Sulphate by reacting Zinc Sulphate with Calcium Oxide or lime. We get a precipitate of Calcium Sulphate. The reaction can be written as-
${ZnSO} _{4}$ ${+}$ ${CaO}$ ${=}$ ${CaSO} _{4}$ ${+}$ ${ZnO}$

The chemical formula of Epsom Salt is ${MgSO} _{4}$${.}$${7H} _{2}{O}$. Or it is also known as Magnesium Sulphate heptahydrate.

When $Mg$ is dissolved in dilute Sulphuric acid, an aqueous solution of Magnesium Sulphate is obtained. The reaction can be represented as-
$Mg$ $+$ $H _2SO _4$ $=$ $MgSO _4$ $+$ $H _2$
This colourless aqueous solution when evaporates, colorless crystals of $MgSO _4.7H _2O$ are formed.

When Epsom salt is heated, all the above mentioned products are obtained. When it is heated at $150^o$ C, $MgSO _4.H _2O$ is obtained. When this is further heated at $200^o$ C, $MgSO _4$ is obtained. On further heating $MgO$ and $SO _3$ are obtained.
$MgSO _4.7H _2O$ $+$ $(heat)$ $=$ $MgSO _4.H _2O$  
$MgSO _4.H _2O$ $+$ $(heat)$ $=$ $MgSO _4$
$MgSO _4$ $+$ $(heat)$ $=$ $MgO$ $+$ $SO _3$

The seven molecules of water attached to $MgSO _4.7H _2O$ are known as water of hydration. By definition, it is the amount of water attached to a compound to form a hydrate. Epsom salt is also known as Magnesium sulphate heptahydrate.

Gypsum is mainly used as fertilizer.

When magnesium oxide is dissolved in dilute sulphuric acid, it forms colorless aqueous solution of Magnesium Sulphate. The balanced equation can be written as-
$MgO$ $+$ $H _2SO _4$ $=$ $MgSO _4$ $+$ $H _2O$
This aqueous solution when evaporates and crystallizes, colorless crystals of Epsom salt are obtained.

The two moles of water attached to gypsum is called as "water of hydration".$CaSO _4.2H _2O$

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.

Single superphosphate (SSP) was the first commercial mineral fertilizer, and it led to the development of the modern plant nutrient industry. This material was once the most commonly used fertilizer, but other phosphorus (P) fertilizers have largely replaced SSP because of its relatively low P content.

The general chemical reaction involved in the production of SSP is

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

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.

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.

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.

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.

A mixture of single superphosphate and triple superphosphate is called double superphosphate. More than 90% of a typical superphosphate fertilizer is water-soluble.

Hence option C is correct.

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.

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.

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: ${ Ca } _{ 5 }(OH){ (P{ O } _{ 4 }) } _{ 3 }$.

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 $Cl _2$.

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.

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.

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.

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

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.

$ KCl \cdot MgCl _2 \cdot 6H _2O$ represents carnalite.

Carnalite ($ KCl \cdot MgCl _2 \cdot 6H _2O$) is fused and cooled to 176 deg C.  Potassium content solidifies and $ MgCl _2 \cdot 6H _2O$ remains infused state. Fused mass is separated from deposited $KCl$ and is allowed to cool. The remaining $KCl$ is separated by deposition of carnalite crystals, which crystallizes out first.
$ MgCl _2 \cdot 6H _2O$ is left behind in the fused mass.

When magnesium chloride reacts with calcium hydroxide, $Mg(OH) _2$ and $ CaCl _2(aq) $ are obtained.
$MgCl _2(aq) + Ca(OH) _2(aq) \rightarrow  Mg(OH) _2(s) + CaCl _2(aq) $

Option $(A)$ is correct.

Option $(C)$ is correct.

Option $(A)$ is correct.

Option $(D)$ is correct.

Option $(B)$ is correct.

Option $(B)$ is correct.

Option $(A)$ is correct.

Calcining at different temperatures produces magnesium oxide of different reactivity.

$BeO$ forms amphoteric oxide because it acts as both acidic oxide as well as basic oxide. $MgO,CaO,SrO$ are ionic oxide.

All of the above methods are used for the production of magnesium oxide.when magnesium is burnt in air magnesium oxide is produced. When magnesium carbonate is calcined magnesium oxide and carbon dioxide is produced. When magnesium hydroxide is calcined magnesium oxide and water is produced.

The compounds of alkaline earth metal are diamagnetic because they don't have any unpaired electrons. Their electronic configuration is $np^6ns^2$.

Hemoglobin contains iron, vitamin $B$, cobalt. Chlorophyll contains magnesium. ATP is adenosine triphosphate contains phosphorous.

Sorel cement is a mixture of magnesium chloride and magnesium oxide.

Most abundant mineral of phosphate rock is Fluorapetite, which has the formula of $Ca _5(PO _4) _3F$.

Most abundant mineral of phosphate rock is Fluorapetite, which has the formula of $Ca _5(PO _4) _3F$.

Chlorophyll is a magnesium - porphyrin complex.
Chlorophyll is the main pigment for the absorption of light in plants and is useful during photosynthesis.

The reactions occurring  during the production of superphosphate are complex and are usually summarised as follows :

The reactions occurring  during the production of superphosphate are complex and are usually summarised as follows :

During superphosphate production, silicon tetrafluoride (SiF4) is produced as a byproduct. When this reacts with water, it forms fluorosilicic acid (H2SiF6).

The impurities present in the phosphate rock are silicon and flourine. If phosphate rock is digested in phosphoric acid, silicon dioxide and hydrogen flouride are formed. 

Green vitroil is isomorphous with $MgSO _4.7H _2O$

All three $Mg$, $C$ and $Ne$ have $2nd$ ionisation potential greater than $1st$ ionisation potential. 

$Mg$ does not belong to alkali metal family. Moreover carbonates of $Mg$ are less stable.

Hydrated lime is added to sand and cement so that they don't separate and gypsum is used so that it sets well with the iron pillars or bricks,etc.

Gypsum plays a very important role in controlling the rate of hardening of the cement. It slows sown the setting of cement so that cement is adequately hardened.

When calcium sulphate is mixed with conc. HCl the paste is formed. When this paste is brought near the flame, brick red colour is obtained which is the characteristic colour of calcium.

Dead burnt plaster is anhydrous calcium sulfate (CaSO4), also known as anhydrite, formed by heating gypsum to high temperatures.

$MgO$ has highest melting point, because this is ionic in character and has very high lattice energy.
Hence, the answer is $MgO$.

Magnesium oxide (MgO) is a white, high-melting crystalline solid used in refractories.

Magnesium react with hydrogen to produce magnesium hydride. chemical equations is as: 

$MgCl _2$ is colourless, crystalline, deliquescent solid which is highly soluble in water.

The following represents the use(s) of Sorel's cement.

1. It sets to a hard white mass. Hence, it is used as a dental stopping.
   
2. It takes a very good polish and is used as a finish for plaster.
   
3. It is used for cementing glass and metal together.

When magnesium burns, it is actually reacting with oxygen in the air and not with fire. Fire is what we call the heat and light produced when things burn Magnesium reacts with oxygen to make a compound called magnesium oxide. The bright light results because this reaction produces a lot of heat. so given statement is false

It is produced by the calcination of magnesium carbonate or magnesium hydroxide.The latter is obtained by the treatment of magnesium chloride solutions, typically seawater, with lime.

Calcium Fluoride is treated with Sulphuric Acid to give Hydrogen Fluoride and a precipitate of Calcium Sulphate. The balanced equation can be written as-
${CaF} _{2}$ ${+}$ ${H} _{2}{SO} _{4}$ ${=}$ ${2HF}$ ${+}$ ${CaSO} _{4}$

Magnesium oxide is used in all these applications: it acts as a mild desiccant, is a primary material in the refractory industry, is a component in cement, and is used as an antacid.

Option $(D)$ is correct.

There are two types of sorel cement 3 phase and 5 phase.