Q 12) Solubility product principle and common ion effect helps to predict the formation of precipitate.
a) What do you mean by common ion effect? Explain with suitable example.
Solution: The suppression of dissociation of a weak electrolyte when a strong electrolyte is added to its solution having a common ion.
For example: The dissociation of $CH_3COOH$ is suppressed by the addition of $HCl$.$$\rm CH_3COOH \rightarrow H^+ CH_3COO^-$$$$\rm HCl \rightarrow H^+ + Cl^-$$When $HCl$ is added to $CH_3COOH$, the concentration of $H^+$ ion in the mixture increases. To compensate for the loss, either more $CH_3COOH$ should be dissociated or it should follow backward reaction. As a result, the concentration of $CH_3COOH$ decreases because it is a weak electrolyte.
Q 12 )
Q 13) Standard solution of oxalic acid is used to determine the strength of KMnO4 during titration.
a) Define redox titration with suitable examples. Why is it called so?
Solution: Redox titration is defined as a process of determination of concentration of a titrand through a redox reaction between the titrand and the titrant. An example of redox titration is the titration between Oxalic acid and KMnO4.
It is called so as it involved the oxidation-reduction reaction between the titrand and the titrant.
b) How much NaCl salt is formed by adding 100 mL of 0.1 N HCl to 200 mL of 0.1 N NaOH solution?
Solution:
Q 14) Formation of alloy and complex formations are the common properties of transition metal.
a) What are the factors that affect the formation of metal complexes?
Solution: The formation of metal complexes depends upon the size of metal ion, size and shape of ligand, and nature of ligand.
b) Give reasons why they have ability to form complex and alloy.
Solution: Transition metal have the ability to form complex and alloy because of their small sized atoms, high nuclear charge, and vacant d-orbitals to accomodate incoming electrons from ligands. Also, transition metals are miscible with one another in molten state which favours formation of alloy.
c) Define co-ordination number. What is the coordination number of ferrous ions in ferric ferrocyanide complex?
Solution: Co-ordination number is defined as the total number of pair of electrons donated by the ligands to central metal atom during complex formation.
Coordination number of ferrous ions in ferric ferrocyanide Fe4[Fe(CN)6]3 complex is six (6).
Q 15) Blue vitriol is pentra-hydrated copper sulphate.
a) Starting from copper how would you prepare blue vitriol?
Solution: To prepare blue vitriol from copper, one can use the following steps: $$\rm Cu + H_2SO_4 \rightarrow CuSO_4 + H_2O$$$$\rm CuSO_4 + 5 H_2O \rightarrow CuSO_4 \cdot 5H_2O$$Hence, CuSO4.5H2O is blue vitriol.
b) A light blue colored ppt. M is formed when blue vitriol is treated with caustic soda which on heating gives black precipitate N. What are M and N?
Solution: Light blue coloured ppt. is due to the formation of Copper hydroxide (M).$$\rm CuSO_4 + NaOH \rightarrow Cu(OH)_2 + Na_2SO_4$$Black precipitate (N) is due to the formation of Copper Oxide.$$\rm Cu(OH)_2 \rightarrow ^ \triangle CuO + H_2O$$
c) What happens when CuSO4 is warmed with glucose in alkaline medium?
Solution:
Q 17) Fermentation is the oldest method to manufacture alcohol.
a) Define molasses.
Solution: Molasses is defined as the mother liquor left after the cyrstallization of sugarcane.
b) Starting from sucrose, how would you obtain ethanol by fermentation process?
Solution:
c) How can you distinguish between two alcoholic isomers of $\rm C_3H_8O$ by Victor Meyer’s method?
Solution:
Q 20 a) Define order of reaction. Why is the rate law an experimental parameter?
Solution: Order of reaction for a reaction is defined as the sum of exponents of reactants present in the rate law equation.
It is an experimental parameter because it cannot be derived theoretically. For a particular reaction, its value is assigned after studying the chemical reaction in the laboratory.
Q 20 b) For the reaction Cl2 + 2 NO —> 2 NOCl, the data obtained are
| Experiment No | [Cl2] mol/L | [NO] mol/L | Initial rate mol/Lsec |
| 1 | 0.02 | 0.01 | $\rm 2.4 \times 10^{-4}$ |
| 2 | 0.02 | 0.03 | $\rm 2.16 \times 10^{-3}$ |
| 3 | 0.04 | 0.03 | $\rm 4.32 \times 10^{-3}$ |
Find the overall order of the reaction.
Solution: The overall order of the reaction is 3.
Q 20 c) Define enthalpy of formation. The bond dissociation energy of $H_{2 (g)}$ and $Cl_{2 (g)}$ are 435 and 243 KJ/mol respectively. The enthalpy of formation of HCl (g) is -92 KJ/mol. Calculat bond dissociation energy of HCl.
Solution: The total amount of heat change involved when one mole of a chemical substance is formed from its constituent elements is defined as enthalpy of formation.
Q 21 a) Define chromophores and auxochromes with examples.
Solution: Chromophores are a part of dyes that are responsible for the color of dye. Example: $\rm – N = N -$ (azo group), $- NO_2$ (nitro group), etc.
Auxochromes are a part of dyes that intensify the color of a dye. Example: $\rm -OH, SO_3H$, etc.
In a dye, both chromophores and auxochromes must be present.
Q 21 b) What do you mean by radioisotopes? Give example. Write any application of any two radioisotopes.
Solution: Radio isotopes are those isotopic forms of a chemical element that can exhibit radioactivity. Example: $^{14}_6C$ is a radioisotope of carbon.
Any application of any two radioisotopes are as follows:
a) C-14 is used in the study of photosynthesis of plant.
b) Cobalt-60 is used for controlling cancer growth.
Q 21 c) Write any four differences between OPC and PPC.
Solution: Any four differences between OPC and PPC are as follows:
1) OPC stands for Ordinary Portland Cement whereas PPC stands for Portland Pozzolana Cement.
2) OPC is prepared from a mixture of limestone and other raw materials like agrillaceous, calcaerous, gypsum, etc. whereas PPC is formed by adding Pozzolanic materials to OPC.
3) OPC is slightly cosliter than PPC whereas PPC is cheapter than OPC.
4) OPC comes in different grades such as OPC 33, OPC 43, OPC 53; but PPC has no any specific grades.
Q 21 d) Draw the flow-sheet diagram for manufacture of paper.
Solution:
Q 22) An organic compound (X) under goes ozonolysis to give compound (Y) and (Z). The aliphatic compound (Y) gives lactic acid on treating with HCN followed by hydrlysis. The compound Z doesn’t reduce tollens reagent but gives acetoxime with NH2OH.
a) Identify the compound (X), (Y) and (Z) with required reaction.
Solution:
b) What happens when compound Y is treated with dil. NaOH?
Solution:
c) Convert compound (Y) into (Z).
Solution:
d) Prepare the compound (Z) from the following compound
i) 2,2 – dibromopropane
Solution:
ii) Propyne
Solution:
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