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Exercise on Chemistry Paper 4= 2014= form 5. Preparation for Practical chemistry. Paper 4- practical chemistry. 2 sections ( 1 ½ hour) Part A) carrying out experiment Example, taking volume, temperature, mass, time Then do calculations
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Exercise on Chemistry Paper 4= 2014= form 5 Preparation for Practical chemistry
Paper 4- practical chemistry • 2 sections ( 1 ½ hour) • Part A) carrying out experiment Example, taking volume, temperature, mass, time Then do calculations Part B) salt analysis – given unknown salt, you are asked to determine what the salt is
Salt analysis • To identify cations ( ions that go to the cathode , that is positive ions) • To identify anions ( ions that go to the anode , that is negative ions )
SALT ANALYSIS - cations No change blue
NO NO
How to test zinc ion shake
White ppt sodium
green cyanoferrate Potassium brown
Test for anions Brown ring formed
Test for anions Bubbles of gas produced that turn lime water cloudy
Test for anions White precipitate
Test for anions White precipitate
metal decompose
3) Solubility of salts silver calcium
Soluble and insoluble in water Insoluble in water Soluble in water
4) Colour of substances carbonate Green Brown
Yellow Orange Black
white yellow brown yellow
Zinc carbonate Mg 2+ ion/ magnesium ion
Al 3+ OR Pb 2+ ion Zn 2+ ion
Ca 2+ ion Fe 3+ ion
Cl – ion Chloride ion CO32- ion Carbonate ion
NO3– ion Nitrate ion SO42– ion sulphate ion
Pb 2+ ion/ lead(II) ion Al 3+ ion / aluminium ion
Salt Y • Gas CO2 • Salt Y is carbonate salt • Residue is lead(II) oxide
Salt Y • Residue is a carbonate salt
X contains Pb2+ ion • Lead(II) carbonate
Salt W is zinc nitrate . Fill in the table below for expected results • Brown gas and • gas that rekindle glowing wooden splinter formed • Residue is yellow when hot and white when cold • NO2 gas and O2 gas • Y contains nitrate • Residue is zinc oxide
Salt W is zinc nitrate . Fill in the table below for expected results • Residue dissolves in acid • Residue is a base
Add NaOH solution, little first, then in excess • X contains Zn2+ / Al3+ /Pb2+ • White precipitate, soluble in excess
Add NH3 aq, solution, little first, then in excess • X contains Zn2+ • White precipitate, soluble in excess
Question 3 – Solution Q is magnesium chloride • Add NaOH solution, little first, then in excess • X contains Mg2+ / Ca2+ • White precipitate
Add NH3 solution, little first, then in excess • X contains Mg2+ • White precipitate
Add HCl followed by barium chloride solution • No sulphate ion • No change
Add nitric acid followed by AgNO3 solution • Chloride ion present • White precipitate