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 while the base is Zinc Hydroxide .
(ii) Describe the observations for the reaction.
Zinc Nitrate and Ammonia Hydroxide are colorless solutions . When added together,
a colorless solution, Ammonium Nitrate, and a white insoluble precipitate, Zinc Hydoxide is formed .
(iii) Write a chemical equation for the reaction (include state symbols).
Zn(NO3)2 (aq) + 2NH4OH (aq) --> 2NH4NO3 (aq) + Zn(OH)2 (s)
(iv) Write an ionic equation for the reaction.
Zn2+ (aq) + 2OH- (aq) -->Zn(OH)2 (s)
Question 2
Ammonium sulfate is heated with sodium hydroxide.
(i) Write a chemical equation (include state symbols) for the reaction.
(NH4)2SO4 (aq) + 2NaOH (aq) --> Na2SO4 (aq) + 2H2O (l) + 2NH3 (g)
(ii) Describe a test for the gas.
Hold a piece of damp red litmus paper over the mouth of the test tube containing ammonia gas. It will turn damp red litmus paper to blue .
Question 3
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.
The gas evolved is Ammonia gas.
(ii) This is a confirmatory test for an anion. Name this anion.
It is Nitrate.
(iii) Give a possible cation which gives the green solution.
Iron(II) ion.
Question 4
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.
Titration method is to prepare Group (I) salt or Ammonium salt. Potassium sulfate is Group (I) salt and it is soluble. Sulfuric acid and Potassium Hydroxide are both colourless solution. Hence by using titration, we add the indicator to ensure that the neutralization change to a permanent colour to show that neutralization has completed and record the volume. Then we can use the correct volume of 2 solutions for preparation of this salt.
(ii) Write an ionic equation for the reaction.
H2SO4 (aq) + 2KOH (aq) --> K2SO4 (aq) + 2H2O (l)
Question 5
Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt.
(i) Write an ionic equation for the reaction
ZnCO3 (aq) + 2HCl (aq) --> ZnCl2 (aq) + H2O (l) + CO2 (g)
(ii) Why excess zinc carbonate is used?
Excess zinc carbonate to ensure that all the hydrochloric acid has fully and completely reacted with the zinc carbonate before filtering out the excess unreacted solid from the salt solution.
(iii) Briefly explain how the zinc chloride crystals can be obtained.
Add excess zinc carbonate to a beaker the hydrochloric acid first until excess solid is left unreacted behind. Filter to remove the excess unreacted zinc carbonate. Evaporate the zinc chloride solution to remove water to make a saturated salt solution. The hot saturated solution form zinc chloride crystals when it is cooled. This is how the zinc chloride crystals can be obtained.
Me and my mother at genting highland.
Me and shuyu .1) Aleen (27)
Answers are detailed and well written. Pictures were drawn neatly and clearly .There are some spelling mistakes like 'moer' in question 2 . Some pictures were found in google and uploaded as well for our reference. For question 1 , she could draw a atom to show how does a atom looks like. I like her answer for question 5 as she gave some extra infomation about other metals and non-metals, like water and lemon which is a non-metal conduct electricity. Blog is nicely done and there is even music for us to listen while we are reading her answer.
2) Shu Yu (12)
Answers are simple and easy to understand. Pictures were taken and uploaded. Some spelling mistakes like "ocnfiguration". For question 1 , maybe she can elaborate more about the sub-atomic. I like the way she did question 5. She listed it down in point form. It is easier to see the important points. She listed down the chemical properties and physical properties of metal and non-metal .Blog is nicely done too.
3) Wan Ling (16)
Answers are easy to understand. Not too wordy. Pictures are clear and nice. For questions 2 and 3 , she could have drawn the atoms and ions to show that she understand how to draw it. For question 3 , the sulfur ion, it should have brackets and the 2- should be outside the bracket instead of inside the circle . I think she did a good job on question 1. I like the part where she wrote this "Mass number/ Nucleon number/ Ar (relative atomic mass) : protons = neutrons Proton number=Atomic number No. of electrons=No. of protons No. of neutrons=Nucleon number-no. of protons" its is very detailed and very easy to understand. The pictures taken from websites can be as a reference . Blog is nicely done.
An atom is the smallest part of matter that consist of subatomic particles. Atom is made up of three different particles protons, neutrons and electrons. This particles are known as sub-atomic particles. Protons and neutrons are tightly packed together in the centre of an atom, forming the nucleus of the atom. Protons and neutrons are also known as nucleons. All atoms are electrically neutral. An atom contains an equal number of positively charged protons and negatively charged electrons. The positive and the negative electric charges cancel out exactly. Each protons carries 1 positive electric charge (+1) and has a relative mass of 1 . Each neutron carries no electric charge and has a relative mass of 1 . Each electron carries 1 negative electric (-1) and has a relative mass of 1/1840Electrons in an atom move around the nucleus in regions known as electron shells. Each electron shell can only hold a certain number of electrons. First shell which is closest to the nucleus, can hold a maximum of two electrons. Second, third and subsequent shells can hold up to eight electrons each. Th shell that is furthest from the nucleus is called the outer shell or the valance shell. The electrons in the shell are called valence electrons.
2. Draw the atomic structure of a sodium atom and a sodium ion....explain why you draw it this way.
An sodium atom has a proton number of 11. Thus the first shell consist of 2 electrons, second shell consist of 8 electrons and the valence shell consist of 1 electron. A sodium ion has a proton number of 10 as it loses 1 electons to achieve stability. This forms a positively charged ion.
3. Draw the atomic structure of a sulfur atom and a sulfide ion....explain why you draw it this way.
An sulfur atom has a proton number of 16. Thus the first shell consist of 2 electrons, second shell consist of 8 electrons and the valence shell consist of 6 electron. A sulfur ion has a proton number of 18 as it gains 2 electons to achieve stability. This forms a negatively charged ion.
4. Chlorine-35 atom and Chlorine-37 atom are called isotopes...Use these two examples to explain what is 'isotopes'
Chlorine-35 has a relative atomic mass number of 35.Chlorine-35 has 17 protons and 18 neutrons. As the nucleon number is 35 consisting of protons and neutrons (35n&p-17P=18n). Chlorine-37 has a relative atomic mass of 37.Chlorine-37 has 17 protons and 20 neutrons. As the nucleon number is 37 consisting of protons and neutrons (37p&n - 17p = 20n). They have the same number of protons but different number of neutrons. Chlorine-35 has 18 neutrons while Chlorine-37 has 20 neutrons. We know that isotopes are different atoms of the same element which have the same number of protons but different number of neutrons. Therefore, Chlorine-35 and Chlorine-37 are called isotopes as they are the different atoms of the same element, chlorine, only that they have different number of neutrons but same number of protons.
5. Sodium is a metal and sulfur is a non-metal....why we classify them this way??
PHYSICAL PROPERTIES
Group (I), (II), (III) of the periodic table are metals. Transition metals ( coloured metals ) are are also metals. Sodium is group (I). Therefore, it is a metal. Group (IV), (V), (VI), (VII), (VIII)/0 of the periodic table are non-metals. Sulfur is group (VI). Therefore, it is non-metal. Metals conduct electricity whereas non-metals do not conduct electricity. Sodium conduct electricity whereas sulfur do not conduct electricity.
CHEMICAL PROPERTIES
As we know, atoms of metals tend to lose valence electrons to form positive charged ions. Atom of non-metals tends to gain valence electrons to form negative charged ions. Metals have less than 5 electrons in the valence shell will lose electrons and while non-metals have more than 4 electrons in the valance shell will gain electrons. Sodium has a proton number of 11 . It has 1 valence electron, thus it loses 1 electron to achieve stabilitly. Sodium become a positively charged ion . Therefore, sodium is a metal. Whereas, Sulfur has a proton number of 16. It has 6 valance electrons , thus it gains 2 electrons to achieve stability and become a negatively charged ion. Therefore, Sulfur is a non-metal.
Acknowledgement
Textbook, notes, assessment book and my knowledge.
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Lee Hwee Leng 
