JK-TK/Newdata huggingface dataset:
Warm/heat gently on Bunsen flame. Pour the mixture into a beaker containing 50cm3 of water. Smell the products. Repeat with a solution of succinic acid, citric acid, oxalic acid, tartaric acid and dilute sulphuric (VI) acid. Sample observations Solution/acid Observations Ethanoic acid Sweet fruity smell Succinic acid Sweet fruity smell Citric acid Sweet fruity smell Oxalic acid Sweet fruity smell Tartaric acid Sweet fruity smell Dilute sulphuric(VI)acid No sweet fruity smell Explanation Alkanols react with alkanoic acid to form the sweet smelling homologous series of esters and water.The reaction is catalysed by concentrated sulphuric(VI)acid in the laboratory but naturally by sunlight /heat.Each ester has a characteristic smell derived from the many possible combinations of alkanols and alkanoic acids. Alkanol + Alkanoic acids -> Ester + water Esters derive their names from the alkanol first then alkanoic acids. The alkanol “becomes” an alkyl group and the alkanoic acid “becomes” alkanoate hence alkylalkanoate. e.g. Ethanol + Ethanoic acid -> Ethylethanoate + Water Ethanol + Propanoic acid -> Ethylpropanoate + Water Ethanol + Methanoic acid -> Ethylmethanoate + Water Ethanol + butanoic acid -> Ethylbutanoate + Water Propanol + Ethanoic acid -> Propylethanoate + Water Methanol + Ethanoic acid -> Methyethanoate + Water Methanol + Decanoic acid -> Methyldecanoate + Water Decanol + Methanoic acid -> Decylmethanoate + Water
32 During the formation of the ester, the “O” joining the alkanol and alkanoic acid comes from the alkanol. R1 -COOH + R2 –OH -> R1 -COO –R2 + H2O Examples 1. Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate and water. Ethanol + Ethanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C2H5OH (l) + CH3COOH(l) --Conc.
Ethanol reacts with ethanoic acid to form the ester ethyl ethanoate and water. Ethanol + Ethanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C2H5OH (l) + CH3COOH(l) --Conc. H2SO4 --> CH3COO C2H5(aq) +H2O(l) CH3CH2OH (l)+ CH3COOH(l) --Conc. H2SO4 --> CH3COOCH2CH3(aq) +H2O(l) 2. Ethanol reacts with propanoic acid to form the ester ethylpropanoate and water. Ethanol + Propanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C2H5OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 -->CH3CH2COO C2H5(aq) +H2O(l) CH3CH2OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 --> CH3 CH2COOCH2CH3(aq) +H2O(l) 3. Methanol reacts with ethanoic acid to form the ester methyl ethanoate and water. Methanol + Ethanoic acid --Conc. H2SO4 -->Methylethanoate + Water CH3OH (l) + CH3COOH(l) --Conc. H2SO4 --> CH3COO CH3(aq) +H2O(l) 4. Methanol reacts with propanoic acid to form the ester methyl propanoate and water. Methanol + propanoic acid --Conc. H2SO4 -->Methylpropanoate + Water CH3OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 --> CH3 CH2COO CH3(aq) +H2O(l) 5. Propanol reacts with propanoic acid to form the ester propylpropanoate and water. Propanol + Propanoic acid --Conc.
H2SO4 --> CH3 CH2COO CH3(aq) +H2O(l) 5. Propanol reacts with propanoic acid to form the ester propylpropanoate and water. Propanol + Propanoic acid --Conc. H2SO4 -->Ethylethanoate + Water C3H7OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 -->CH3CH2COO C3H7(aq) +H2O(l) CH3CH2 CH2OH (l)+ CH3 CH2COOH(l) --Conc. H2SO4 --> CH3 CH2COOCH2 CH2CH3(aq) +H2O(l)
33 C. DETERGENTS Detergents are cleaning agents that improve the cleaning power /properties of water.A detergent therefore should be able to: (i)dissolve substances which water can not e.g grease ,oil, fat (ii)be washed away after cleaning. There are two types of detergents: (a)Soapy detergents (b)Soapless detergents (a) SOAPY DETERGENTS Soapy detergents usually called soap is long chain salt of organic alkanoic acids.Common soap is sodium octadecanoate .It is derived from reacting concentrated sodium hydroxide solution with octadecanoic acid(18 carbon alkanoic acid) i.e. Sodium hydroxide + octadecanoic acid -> Sodium octadecanoate + water NaOH(aq) + CH3 (CH2) 16 COOH(aq) -> CH3 (CH2) 16 COO – Na+ (aq) +H2 O(l) Commonly ,soap can thus be represented ; R- COO – Na+ where; R is a long chain alkyl group and -COO – Na+ is the alkanoate ion. In a school laboratory and at industrial and domestic level,soap is made by reacting concentrated sodium hydroxide solution with esters from (animal) fat and oil. The process of making soap is called saponification. During saponification ,the ester is hydrolyzed by the alkali to form sodium salt /soap and glycerol/propan-1,2,3-triol is produced.
In a school laboratory and at industrial and domestic level,soap is made by reacting concentrated sodium hydroxide solution with esters from (animal) fat and oil. The process of making soap is called saponification. During saponification ,the ester is hydrolyzed by the alkali to form sodium salt /soap and glycerol/propan-1,2,3-triol is produced. Fat/oil(ester)+sodium/potassium hydroxide->sodium/potassium salt(soap)+ glycerol Fats/Oils are esters with fatty acids and glycerol parts in their structure; C17H35COOCH2 C17H35COOCH C17H35COOCH2
34 When boiled with concentrated sodium hydroxide solution NaOH; (i)NaOH ionizes/dissociates into Na+ and OH- ions (ii)fat/oil split into three C17H35COO- and one CH2 CH CH2 (iii) the three Na+ combine with the three C17H35COO- to form the salt C17H35COO- Na+ (iv)the three OH-ions combine with the CH2 CH CH2 to form an alkanol with three functional groups CH2 OH CH OH CH2 OH(propan-1,2,3-triol) C17H35COOCH2 CH2OH C17H35COOCH +NaOH -> 3 C17H35COO- Na+ + CHOH C17H35COOCH2 CH2OH Ester Alkali Soap glycerol Generally: CnH2n+1COOCH2 CH2OH CnH2n+1COOCH +NaOH -> 3 CnH2n+1COO- Na+ + CHOH CnH2n+1COOCH2 CH2OH Ester Alkali Soap glycerol R - COOCH2 CH2OH R - COOCH +NaOH -> 3R-COO- Na+ + CHOH R- COOCH2 CH2OH Ester Alkali Soap glycerol During this process a little sodium chloride is added to precipitate the soap by reducing its solubility. This is called salting out. The soap is then added colouring agents ,perfumes and herbs of choice.
Fat/oil(ester)+sodium/potassium hydroxide->sodium/potassium salt(soap)+ glycerol Fats/Oils are esters with fatty acids and glycerol parts in their structure; C17H35COOCH2 C17H35COOCH C17H35COOCH2
34 When boiled with concentrated sodium hydroxide solution NaOH; (i)NaOH ionizes/dissociates into Na+ and OH- ions (ii)fat/oil split into three C17H35COO- and one CH2 CH CH2 (iii) the three Na+ combine with the three C17H35COO- to form the salt C17H35COO- Na+ (iv)the three OH-ions combine with the CH2 CH CH2 to form an alkanol with three functional groups CH2 OH CH OH CH2 OH(propan-1,2,3-triol) C17H35COOCH2 CH2OH C17H35COOCH +NaOH -> 3 C17H35COO- Na+ + CHOH C17H35COOCH2 CH2OH Ester Alkali Soap glycerol Generally: CnH2n+1COOCH2 CH2OH CnH2n+1COOCH +NaOH -> 3 CnH2n+1COO- Na+ + CHOH CnH2n+1COOCH2 CH2OH Ester Alkali Soap glycerol R - COOCH2 CH2OH R - COOCH +NaOH -> 3R-COO- Na+ + CHOH R- COOCH2 CH2OH Ester Alkali Soap glycerol During this process a little sodium chloride is added to precipitate the soap by reducing its solubility. This is called salting out. The soap is then added colouring agents ,perfumes and herbs of choice. School laboratory preparation of soap Place about 40 g of fatty (animal fat)beef/meat in 100cm3 beaker .Add about 15cm3 of 4.0M sodium hydroxide solution. Boil the mixture for about 15minutes.Stir the mixture .Add about 5.0cm3 of distilled water as you boil to make up for evaporation.
The soap is then added colouring agents ,perfumes and herbs of choice. School laboratory preparation of soap Place about 40 g of fatty (animal fat)beef/meat in 100cm3 beaker .Add about 15cm3 of 4.0M sodium hydroxide solution. Boil the mixture for about 15minutes.Stir the mixture .Add about 5.0cm3 of distilled water as you boil to make up for evaporation. Boil for about another 15minutes.Add about four spatula end full of pure sodium chloride crystals. Continue stirring for another five minutes. Allow to cool. Filter of
35 /decant and wash off the residue with distilled water .Transfer the clean residue into a dry beaker. Preserve. The action of soap Soapy detergents: (i)act by reducing the surface tension of water by forming a thin layer on top of the water. (ii)is made of a non-polar alkyl /hydrocarbon tail and a polar -COO-Na+ head. The non-polar alkyl /hydrocarbon tail is hydrophobic (water hating) and thus does not dissolve in water .It dissolves in non-polar solvent like grease, oil and fat. The polar -COO-Na+ head is hydrophilic (water loving)and thus dissolve in water. When washing with soapy detergent, the non-polar tail of the soapy detergent surround/dissolve in the dirt on the garment /grease/oil while the polar head dissolve in water. Through mechanical agitation/stirring/sqeezing/rubbing/beating/kneading, some grease is dislodged/lifted of the surface of the garment. It is immediately surrounded by more soap molecules It float and spread in the water as tiny droplets that scatter light in form of emulsion making the water cloudy and shinny. It is removed from the garment by rinsing with fresh water.The repulsion of the soap head prevent /ensure the droplets do not mix.Once removed, the dirt molecules cannot be redeposited back because it is surrounded by soap molecules. Advantages and disadvantages of using soapy detergents Soapy detergents are biodegradable. They are acted upon by bacteria and rot.They thus do not cause environmental pollution. Soapy detergents have the diadvatage in that: (i)they are made from fat and oils which are better eaten as food than make soap.
Advantages and disadvantages of using soapy detergents Soapy detergents are biodegradable. They are acted upon by bacteria and rot.They thus do not cause environmental pollution. Soapy detergents have the diadvatage in that: (i)they are made from fat and oils which are better eaten as food than make soap. (ii)forms an insoluble precipitate with hard water called scum. Scum is insoluble calcium octadecanoate and Magnesium octadecanoate formed when soap reacts with Ca2+ and Mg2+ present in hard water. Chemical equation 2C17H35COO- Na+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2Na+(aq) (insoluble Calcium octadecanote/scum) 2C17H35COO- Na+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2Na+(aq) (insoluble Magnesium octadecanote/scum) This causes wastage of soap. Potassium soaps are better than Sodium soap. Potassium is more expensive than sodium and thus its soap is also more expensive. (b)SOAPLESS DETERGENTS
36 Soapless detergent usually called detergent is a long chain salt fromed from byproducts of fractional distillation of crude oil.Commonly used soaps include: (i)washing agents (ii)toothpaste (iii)emulsifiers/wetting agents/shampoo Soapless detergents are derived from reacting: (i)concentrated sulphuric(VI)acid with a long chain alkanol e.g. Octadecanol(18 carbon alkanol) to form alkyl hydrogen sulphate(VI) Alkanol + Conc sulphuric(VI)acid -> alkyl hydrogen sulphate(VI) + Water R –OH + H2SO4 -> R –O-SO3H + H2O (ii)the alkyl hydrogen sulphate(VI) is then neutralized with sodium/potassium hydroxide to form sodium/potassium alkyl hydrogen sulphate(VI) Sodium/potassium alkyl hydrogen sulphate(VI) is the soapless detergent.
Potassium is more expensive than sodium and thus its soap is also more expensive. (b)SOAPLESS DETERGENTS
36 Soapless detergent usually called detergent is a long chain salt fromed from byproducts of fractional distillation of crude oil.Commonly used soaps include: (i)washing agents (ii)toothpaste (iii)emulsifiers/wetting agents/shampoo Soapless detergents are derived from reacting: (i)concentrated sulphuric(VI)acid with a long chain alkanol e.g. Octadecanol(18 carbon alkanol) to form alkyl hydrogen sulphate(VI) Alkanol + Conc sulphuric(VI)acid -> alkyl hydrogen sulphate(VI) + Water R –OH + H2SO4 -> R –O-SO3H + H2O (ii)the alkyl hydrogen sulphate(VI) is then neutralized with sodium/potassium hydroxide to form sodium/potassium alkyl hydrogen sulphate(VI) Sodium/potassium alkyl hydrogen sulphate(VI) is the soapless detergent. alkyl hydrogen + Potassium/sodium -> Sodium/potassium + Water sulphate(VI) hydroxide alkyl hydrogen sulphate(VI) R –O-SO3H + NaOH -> R –O-SO3- Na+ + H2O Example Step I : Reaction of Octadecanol with Conc.H2SO4 C17H35CH2OH (aq) + H2SO4 -> C17H35CH2-O- SO3- H+ (aq) + H2O (l) octadecanol + sulphuric(VI)acid -> Octadecyl hydrogen sulphate(VI) + water Step II: Neutralization by an alkali C17H35CH2-O- SO3- H+ (aq) + NaOH -> C17H35CH2-O- SO3- Na+ (aq) + H2O (l) Octadecyl hydrogen + sodium/potassium -> sodium/potassium octadecyl+Water sulphate(VI) hydroxide hydrogen sulphate(VI) School laboratory preparation of soapless detergent Place about 20g of olive oil in a 100cm3 beaker. Put it in a trough containing ice cold water.
Octadecanol(18 carbon alkanol) to form alkyl hydrogen sulphate(VI) Alkanol + Conc sulphuric(VI)acid -> alkyl hydrogen sulphate(VI) + Water R –OH + H2SO4 -> R –O-SO3H + H2O (ii)the alkyl hydrogen sulphate(VI) is then neutralized with sodium/potassium hydroxide to form sodium/potassium alkyl hydrogen sulphate(VI) Sodium/potassium alkyl hydrogen sulphate(VI) is the soapless detergent. alkyl hydrogen + Potassium/sodium -> Sodium/potassium + Water sulphate(VI) hydroxide alkyl hydrogen sulphate(VI) R –O-SO3H + NaOH -> R –O-SO3- Na+ + H2O Example Step I : Reaction of Octadecanol with Conc.H2SO4 C17H35CH2OH (aq) + H2SO4 -> C17H35CH2-O- SO3- H+ (aq) + H2O (l) octadecanol + sulphuric(VI)acid -> Octadecyl hydrogen sulphate(VI) + water Step II: Neutralization by an alkali C17H35CH2-O- SO3- H+ (aq) + NaOH -> C17H35CH2-O- SO3- Na+ (aq) + H2O (l) Octadecyl hydrogen + sodium/potassium -> sodium/potassium octadecyl+Water sulphate(VI) hydroxide hydrogen sulphate(VI) School laboratory preparation of soapless detergent Place about 20g of olive oil in a 100cm3 beaker. Put it in a trough containing ice cold water. Add dropwise carefully 18M concentrated sulphuric(VI)acid stirring continuously into the olive oil until the oil turns brown.Add 30cm3 of 6M sodium hydroxide solution.Stir.This is a soapless detergent. The action of soapless detergents
37 The action of soapless detergents is similar to that of soapy detergents.The soapless detergents contain the hydrophilic head and a long hydrophobic tail. i.e.
Add dropwise carefully 18M concentrated sulphuric(VI)acid stirring continuously into the olive oil until the oil turns brown.Add 30cm3 of 6M sodium hydroxide solution.Stir.This is a soapless detergent. The action of soapless detergents
37 The action of soapless detergents is similar to that of soapy detergents.The soapless detergents contain the hydrophilic head and a long hydrophobic tail. i.e. vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv-COO-Na+ vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv-O-SO3- Na+ (long hydrophobic /non-polar alkyl tail) (hydrophilic/polar/ionic head) The tail dissolves in fat/grease/oil while the ionic/polar/ionic head dissolves in water. The tail stick to the dirt which is removed by the attraction of water molecules and the polar/ionic/hydrophilic head by mechanical agitation /squeezing/kneading/ beating/rubbing/scrubbing/scatching. The suspended dirt is then surrounded by detergent molecules and repulsion of the anion head preventing the dirt from sticking on the material garment. The tiny droplets of dirt emulsion makes the water cloudy. On rinsing the cloudy emulsion is washed away. Advantages and disadvantages of using soapless detergents Soapless detergents are non-biodegradable unlike soapy detergents. They persist in water during sewage treatment by causing foaming in rivers ,lakes and streams leading to marine /aquatic death. Soapless detergents have the advantage in that they: (i)do not form scum with hard water. (ii)are cheap to manufacture/buying (iii)are made from petroleum products but soapis made from fats/oil for human consumption. Sample revision questions 1. Study the scheme below Fat/oil KOH Boiling Sodium Chloride Filtration Filtrate Y Residue X
38 (a)Identify the process Saponification (b)Fats and oils are esters.
(ii)are cheap to manufacture/buying (iii)are made from petroleum products but soapis made from fats/oil for human consumption. Sample revision questions 1. Study the scheme below Fat/oil KOH Boiling Sodium Chloride Filtration Filtrate Y Residue X
38 (a)Identify the process Saponification (b)Fats and oils are esters. Write the formula of the a common structure of ester C17H35COOCH2 C17H35COOCH C17H35COOCH2 (c)Write a balanced equation for the reaction taking place during boiling C17H35COOCH2 CH2OH C17H35COOCH +3NaOH -> 3 C17H35COO- Na+ + CHOH C17H35COOCH2 CH2OH Ester Alkali Soap glycerol (d)Give the IUPAC name of: (i)Residue X Potassium octadecanoate (ii)Filtrate Y Propan-1,2,3-triol (e)Give one use of fitrate Y Making paint (f)What is the function of sodium chloride To reduce the solubility of the soap hence helping in precipitating it out (g)Explain how residue X helps in washing. Has a non-polar hydrophobic tail that dissolves in dirt/grease /oil/fat Has a polar /ionic hydrophilic head that dissolves in water. 39 From mechanical agitation,the dirt is plucked out of the garment and surrounded by the tail end preventing it from being deposited back on the garment. (h)State one: (i)advantage of continued use of residue X on the environment Is biodegradable and thus do not pollute the environment (ii)disadvantage of using residue X Uses fat/oil during preparation/manufacture which are better used for human consumption. (i)Residue X was added dropwise to some water.The number of drops used before lather forms is as in the table below. Water sample A B C Drops of residue X 15 2 15 Drops of residue X in boiled water 2 2 15 (i)State and explain which sample of water is: I. Soft Sample B .Very little soap is used and no effect on amount of soap even on boiling/heating. II. Permanent hard Sample C .
Soft Sample B .Very little soap is used and no effect on amount of soap even on boiling/heating. II. Permanent hard Sample C . A lot of soap is used and no effect on amount of soap even on boiling/heating. Boiling does not remove permanent hardness of water. III. Temporary hard Sample A . A lot of soap is used before boiling. Very little soap is used on boiling/heating. Boiling remove temporary hardness of water. (ii)Write the equation for the reaction at water sample C. Chemical equation 2C17H35COO- K+ (aq) + CaSO4(aq) -> (C17H35COO- )Ca2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum)
40 Chemical equation 2C17H35COO- K+ (aq) + MgSO4(aq) -> (C17H35COO- )Mg2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iii)Write the equation for the reaction at water sample A before boiling.
Boiling remove temporary hardness of water. (ii)Write the equation for the reaction at water sample C. Chemical equation 2C17H35COO- K+ (aq) + CaSO4(aq) -> (C17H35COO- )Ca2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum)
40 Chemical equation 2C17H35COO- K+ (aq) + MgSO4(aq) -> (C17H35COO- )Mg2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iii)Write the equation for the reaction at water sample A before boiling. Chemical equation 2C17H35COO- K+ (aq) + Ca(HCO3)(aq) ->(C17H35COO- )Ca2+ (s) + 2KHCO3 (aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum) Chemical equation 2C17H35COO- K+ (aq) + Mg(HCO3)(aq) ->(C17H35COO- )Mg2+ (s) + 2KHCO3 (aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iv)Explain how water becomes hard Natural or rain water flowing /passing through rocks containing calcium (chalk, gypsum, limestone)and magnesium compounds (dolomite)dissolve them to form soluble Ca2+ and Mg2+ ions that causes water hardness.
(ii)Write the equation for the reaction at water sample C. Chemical equation 2C17H35COO- K+ (aq) + CaSO4(aq) -> (C17H35COO- )Ca2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum)
40 Chemical equation 2C17H35COO- K+ (aq) + MgSO4(aq) -> (C17H35COO- )Mg2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iii)Write the equation for the reaction at water sample A before boiling. Chemical equation 2C17H35COO- K+ (aq) + Ca(HCO3)(aq) ->(C17H35COO- )Ca2+ (s) + 2KHCO3 (aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum) Chemical equation 2C17H35COO- K+ (aq) + Mg(HCO3)(aq) ->(C17H35COO- )Mg2+ (s) + 2KHCO3 (aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iv)Explain how water becomes hard Natural or rain water flowing /passing through rocks containing calcium (chalk, gypsum, limestone)and magnesium compounds (dolomite)dissolve them to form soluble Ca2+ and Mg2+ ions that causes water hardness. (v)State two useful benefits of hard water -Used in bone and teeth formation -Coral polyps use hard water to form coral reefs -Snails use hard water to make their shells 2.Study the scheme below and use it to answer the questions that follow.
Chemical equation 2C17H35COO- K+ (aq) + CaSO4(aq) -> (C17H35COO- )Ca2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum)
40 Chemical equation 2C17H35COO- K+ (aq) + MgSO4(aq) -> (C17H35COO- )Mg2+ (s) + K2SO4(aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iii)Write the equation for the reaction at water sample A before boiling. Chemical equation 2C17H35COO- K+ (aq) + Ca(HCO3)(aq) ->(C17H35COO- )Ca2+ (s) + 2KHCO3 (aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Ca2+(aq) -> (C17H35COO- )Ca2+ (s) + 2K+(aq) (insoluble Calcium octadecanote/scum) Chemical equation 2C17H35COO- K+ (aq) + Mg(HCO3)(aq) ->(C17H35COO- )Mg2+ (s) + 2KHCO3 (aq) (insoluble Calcium octadecanote/scum) Ionic equation 2C17H35COO- K+ (aq) + Mg2+(aq) -> (C17H35COO- )Mg2+ (s) + 2K+(aq) (insoluble Magnesium octadecanote/scum) (iv)Explain how water becomes hard Natural or rain water flowing /passing through rocks containing calcium (chalk, gypsum, limestone)and magnesium compounds (dolomite)dissolve them to form soluble Ca2+ and Mg2+ ions that causes water hardness. (v)State two useful benefits of hard water -Used in bone and teeth formation -Coral polyps use hard water to form coral reefs -Snails use hard water to make their shells 2.Study the scheme below and use it to answer the questions that follow. Olive oil Conc.