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Chemistry blog.
Kho Ziqing, (10)
Yuhua Secondary School, 3e5 Concert Band, Clarinet (: 3rd Oct, Libra :>
Q1) Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base.
(i) Name the salt and the base.
The salt is Ammonium nitrate and the base is Zinc hydroxide.
(ii) Desribe the observation for the reaction.
When zinc nitrate reacts with the aqueous ammonia, white precipitate is form and it is soluble in excess to give a colourless solution.
(iii) Write a chemical equation for the reaction (include state symbols).
ZnNO3 (aq) + 2NH4OH (aq) -> Zn(OH)2 (s) + (NH4)2NO3(aq)
(iv) Write an ionic equation for ther reaction.
Zn^2+ (aq) + 2OH- (aq) -> Zn(OH)2 (s)
Qn2) Ammonium sulfate is heated with sodium hydroxide.
(i) Write a chemical equation (incude state symbols) for the reaction.
(NH4)2SO4 (aq) + 2NAOH (aq) -> NA2SO4 (aq) + 2H2O + 2H3 (g)
(ii) Describe a test for the gas.
It turns damp red litmus paper to blue.
Qn3) An unknown green solution is heated with a piece of aluminium foil and sodium hydroxide solution.
(i) The gas produced turns damp red litmus paper blue. Name the gas evolved.
Ammonia.
(ii) This is a confirmatory test for anion. Name this anion.
Nitrate.
(iii) Give a possible cation which gives the green solution.
Iron (II) ions.
Qn4) Sulfuric acid is titrated with potassium hydroxide in the preparation of potassium sulfate salt.
(i) Explain why this method is recommended for the preparation of this salt.
As potassium hydroxide is a group I soluble salt, therefore, tiltration is recommended for the preparation of this salt.
(ii) Write an ionic equation for the reaction.
H+ (aq) + OH- (aq) -> H2O (l)
Qn5) Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt.
(i) Write an ionic equation for the reaction.
ZnCO3 (s) + H+ (aq) + H2O (l) + CO2 (g)
(ii) Why is excess zinc carbonate used?
To ensure that the zinc carbonate and hydrochloric acid is fully reacted before filtering out the excess unreacted solid from the salt solution.
(iii) Briefly explain how the zinc chloride crystals can be obtained.
Zinc carbonate will be added to the hydrochloric acid first till it is fully reacted and the excess solid is left behind. Then filtrate the zinc chloride solution to remove the excess unreacted solid. Remove the water to make a saturated sat solution, by using evaporation. The hot saturated solution is then left to be cooled to obtain the zinc chloride crystals.
Mrtan
Agnes (14)
Wanling (16)
Xueting (19)
Aleen (27)
Wendy (28)
We'll link others asap (:
June 2011
July 2011
September 2011
designer DancingSheep
Topics learnt
Term1and2 1.Kinetic Particles Theory 2.Element Mixture Compound 3.States of Matter && State Symbol 4.Methods of Purification & Separating Mixtures 5.Collecting dry gases 6.Acids Bases Salt 7.Preparation of Salts 8.Mole Calculations 9.Colour of Substances Term3 1.
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Kho Ziqing, (10)
Yuhua Secondary School, 3e5 Concert Band, Clarinet (: 3rd Oct, Libra :>
{/ --
Friday, September 23, 2011 ( 7:43 AM )
Q1) Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base.
(i) Name the salt and the base.
The salt is Ammonium nitrate and the base is Zinc hydroxide.
(ii) Desribe the observation for the reaction.
When zinc nitrate reacts with the aqueous ammonia, white precipitate is form and it is soluble in excess to give a colourless solution.
(iii) Write a chemical equation for the reaction (include state symbols).
ZnNO3 (aq) + 2NH4OH (aq) -> Zn(OH)2 (s) + (NH4)2NO3(aq)
(iv) Write an ionic equation for ther reaction.
Zn^2+ (aq) + 2OH- (aq) -> Zn(OH)2 (s)
Qn2) Ammonium sulfate is heated with sodium hydroxide.
(i) Write a chemical equation (incude state symbols) for the reaction.
(NH4)2SO4 (aq) + 2NAOH (aq) -> NA2SO4 (aq) + 2H2O + 2H3 (g)
(ii) Describe a test for the gas.
It turns damp red litmus paper to blue.
Qn3) An unknown green solution is heated with a piece of aluminium foil and sodium hydroxide solution.
(i) The gas produced turns damp red litmus paper blue. Name the gas evolved.
Ammonia.
(ii) This is a confirmatory test for anion. Name this anion.
Nitrate.
(iii) Give a possible cation which gives the green solution.
Iron (II) ions.
Qn4) Sulfuric acid is titrated with potassium hydroxide in the preparation of potassium sulfate salt.
(i) Explain why this method is recommended for the preparation of this salt.
As potassium hydroxide is a group I soluble salt, therefore, tiltration is recommended for the preparation of this salt.
(ii) Write an ionic equation for the reaction.
H+ (aq) + OH- (aq) -> H2O (l)
Qn5) Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt.
(i) Write an ionic equation for the reaction.
ZnCO3 (s) + H+ (aq) + H2O (l) + CO2 (g)
(ii) Why is excess zinc carbonate used?
To ensure that the zinc carbonate and hydrochloric acid is fully reacted before filtering out the excess unreacted solid from the salt solution.
(iii) Briefly explain how the zinc chloride crystals can be obtained.
Zinc carbonate will be added to the hydrochloric acid first till it is fully reacted and the excess solid is left behind. Then filtrate the zinc chloride solution to remove the excess unreacted solid. Remove the water to make a saturated sat solution, by using evaporation. The hot saturated solution is then left to be cooled to obtain the zinc chloride crystals.
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i think they call it freedom of speech
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Mrtan
Agnes (14)
Wanling (16)
Xueting (19)
Aleen (27)
Wendy (28)
We'll link others asap (:
{/archives --
watch me waste my life away
June 2011
July 2011
September 2011
{/credits --
designer DancingSheep
{/miscellaneous --
Topics learnt
Term1and2 1.Kinetic Particles Theory 2.Element Mixture Compound 3.States of Matter && State Symbol 4.Methods of Purification & Separating Mixtures 5.Collecting dry gases 6.Acids Bases Salt 7.Preparation of Salts 8.Mole Calculations 9.Colour of Substances Term3 1.