Q5 Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt. (i) Write an ionic equation for the reaction.
(ii) Why excess zinc carbonate is used?
(iii) Briefly explain how the zinc chloride crystals can be obtained.
Answer
i) ZnCO3(S) + 2HCl(aq) ---> ZnCl2(aq) + H2O(L) + CO2(g)
ionic equation: ZnCO3(s) + 2H(+)(aq)---> Zn(2+)(aq) H2O(L) +CO2(g)
ii) to ensure that the hydrochloric acid is completely reacted.
iii) After the hydrochloric acid is comepletely reacted, filter the excess zinc carbonate, heat the filtrate till little amount is left for crystalization and lastly let it cool down and crystals will be form.
Thursday 22 September 2011
Q4 Sulfuric acid is titrated with potassium hydroxide in the preparation of potassium sulfate salt.
(i) Explain why this method is recommended for the preparation for this salt.
(ii) Write an ionic equation for the reaction.
Answers
i) It is a group(I) salt and it is soluble.
ii) H2SO4(aq) + 2KOH(aq)----> k2SO4(aq) + 2H2O(L)
Ionic equation: 2H(+) (aq) + 2OH(-) (aq) ---> 2H2O(L)
(i) Explain why this method is recommended for the preparation for this salt.
(ii) Write an ionic equation for the reaction.
Answers
i) It is a group(I) salt and it is soluble.
ii) H2SO4(aq) + 2KOH(aq)----> k2SO4(aq) + 2H2O(L)
Ionic equation: 2H(+) (aq) + 2OH(-) (aq) ---> 2H2O(L)
Q3 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.
(ii) This is a confirmatory test for an anion. Name this anion.
(iii) Give a possible cation which gives the green solution.
Answers
i) ammonia
ii)Nitrate
iii)iron(III)
(i) The gas produced turns damp red litmus paper blue. Name the gas evolved.
(ii) This is a confirmatory test for an anion. Name this anion.
(iii) Give a possible cation which gives the green solution.
Answers
i) ammonia
ii)Nitrate
iii)iron(III)
Monday 19 September 2011
Q1 Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base.
(i) Name the salt and the base.
(ii) Describe the observations for the reaction.
(iii) Write a chemical equation for the reaction (include state symbols).
(iv) Write an ionic equation for the reaction.
Answers
I) the salt is ammonium nitrate and the base is zinc hydroxide
ii) white solution is form when they are mixed together.
iii)ZnNO3(aq) +NH4OH(aq)-->ZnOH(s)+NH4NO3(aq)
iv)Zn+(aq) + OH-(aq)-->ZnOH(s)
(i) Name the salt and the base.
(ii) Describe the observations for the reaction.
(iii) Write a chemical equation for the reaction (include state symbols).
(iv) Write an ionic equation for the reaction.
Answers
I) the salt is ammonium nitrate and the base is zinc hydroxide
ii) white solution is form when they are mixed together.
iii)ZnNO3(aq) +NH4OH(aq)-->ZnOH(s)+NH4NO3(aq)
iv)Zn+(aq) + OH-(aq)-->ZnOH(s)
Friday 8 July 2011
aleen tan(28) you have a nice blog and your answers are very detailed. for example , you list out all the metals and non-metals, and even have a picture of a periodic table. i have get to know about this chapter better after reading your answer. it is a very good work done and you can go far on your studies, continue to be so detailed and hardworking.
agnes(14)
you have a nice skin and your answers are clean and clear, it is also very detailed. most of your answers are answered nicely with a diagram to further explain which makes people learn better and understand better. this shows that you have put in a lot of effort and time. with this values in your character, you will be able to achieve even higher things. keep up this good work and continue to strive!:)
grace(4)
you have a simple blog yet informative. your answers are detailed and diagrams are clear. however, you can afford to put in more diagram to explain better and provide more information to the answers. but, from your blog, i can understand your answers easily and clearly. you have put in quite a lot of effort but, it is possible for you to put in more to achieve greater results and achievement in the future. keep up the good work and strive harder!
agnes(14)
you have a nice skin and your answers are clean and clear, it is also very detailed. most of your answers are answered nicely with a diagram to further explain which makes people learn better and understand better. this shows that you have put in a lot of effort and time. with this values in your character, you will be able to achieve even higher things. keep up this good work and continue to strive!:)
grace(4)
you have a simple blog yet informative. your answers are detailed and diagrams are clear. however, you can afford to put in more diagram to explain better and provide more information to the answers. but, from your blog, i can understand your answers easily and clearly. you have put in quite a lot of effort but, it is possible for you to put in more to achieve greater results and achievement in the future. keep up the good work and strive harder!
Thursday 7 July 2011
Sunday 3 July 2011
5. Sodium is a metal and sulfur is a non-metal....why we classify them this way??
Group (I),(II),(III) excluding boron are metals. Group (IV),(VI),(VII),(VIII) or group 0 including boron are non-metals.Metals lose electrons and Non-metals gain electrons to complete and stablise the valence shell. therefore sodium are classify under metal as it falls under group(I) and sulfur is a non-metal as it falls under group (VI). Sulfur (2.8.2) is a non-metal as it will gain 2 electrons to complete the valency shell( to make it stable), sodium (2.8.1) is a metal as it will lose 1 electron to complete the valency shell(to make it stable).
Group (I),(II),(III) excluding boron are metals. Group (IV),(VI),(VII),(VIII) or group 0 including boron are non-metals.Metals lose electrons and Non-metals gain electrons to complete and stablise the valence shell. therefore sodium are classify under metal as it falls under group(I) and sulfur is a non-metal as it falls under group (VI). Sulfur (2.8.2) is a non-metal as it will gain 2 electrons to complete the valency shell( to make it stable), sodium (2.8.1) is a metal as it will lose 1 electron to complete the valency shell(to make it stable).
3. Draw the atomic structure of a sulfur atom and a sulfide ion....explain why you draw it this way
An atom do not have charge and its outer most electron shell is not a full shell.
An ion is form when an atom gain or lose electron and form a full shell. ions have charges and can be classify under positive or negative ion. when it gives away electrons, it is a positive ion but when it gain electron, it is a negative charge. therefore, sulfur atom are drawn without charge and sulfide ion are drawn with a negative charge as it gain 2 electron.
Source: picture from Lim Jie En of 3E5
An ion is form when an atom gain or lose electron and form a full shell. ions have charges and can be classify under positive or negative ion. when it gives away electrons, it is a positive ion but when it gain electron, it is a negative charge. therefore, sulfur atom are drawn without charge and sulfide ion are drawn with a negative charge as it gain 2 electron.
Source: picture from Lim Jie En of 3E5
2. Draw the atomic structure of a sodium atom and a sodium ion....explain why you draw it this way.
An atom do not have charge and its outer most electron shell is not a full shell.
An ion is form when an atom gain or lose electron and form a full shell. ions have charges and can be classify under positive or negative ion. when it gives away electrons, it is a positive ion but when it gain electron, it is a negative charge. therefore, sodium atom are drawn without charge and sodium ion are drawn with a positve charge as it give away 1 electron.
Source: picture from Lim Jie En of 3E5
An atom do not have charge and its outer most electron shell is not a full shell.
An ion is form when an atom gain or lose electron and form a full shell. ions have charges and can be classify under positive or negative ion. when it gives away electrons, it is a positive ion but when it gain electron, it is a negative charge. therefore, sodium atom are drawn without charge and sodium ion are drawn with a positve charge as it give away 1 electron.
Source: picture from Lim Jie En of 3E5
4. Chlorine-35 atom and Chlorine-37 atom are called isotopes...Use these two examples to explain what is 'isotopes'
isotopes are differents atom of the same elements with the same amount of protons but differents amount of neutrons. Clorine-35 has 17 protons and 18 neutrons. Clorine-37 has 17 protons and 20 neutrons. in conclusion, they have the same number of protons (17) but different number of neutrons (clorine 35-18, clorine 37- 20) this show that they are isotopes.
Source:---
isotopes are differents atom of the same elements with the same amount of protons but differents amount of neutrons. Clorine-35 has 17 protons and 18 neutrons. Clorine-37 has 17 protons and 20 neutrons. in conclusion, they have the same number of protons (17) but different number of neutrons (clorine 35-18, clorine 37- 20) this show that they are isotopes.
Source:---
1. What does an atom looks like? What are the sub-atomic particles inside it.....(talk about electrons, neutrons, protons, electron shells, nucleus....)
An atom is made up of 3 types of particles. they the protons, neutrons and electrons.These particles have different properties. Electrons are tiny, very light particles that have a negative electrical charge (-). Protons are much larger and heavier than electrons and have the opposite charge, protons have a positive charge. Neutrons are large and heavy like protons, however neutrons have no electrical charge. Each atom is made up of a combination of these particles.
Source:http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm
An atom is made up of 3 types of particles. they the protons, neutrons and electrons.These particles have different properties. Electrons are tiny, very light particles that have a negative electrical charge (-). Protons are much larger and heavier than electrons and have the opposite charge, protons have a positive charge. Neutrons are large and heavy like protons, however neutrons have no electrical charge. Each atom is made up of a combination of these particles.
Source:http://web.jjay.cuny.edu/~acarpi/NSC/3-atoms.htm
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