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Practice each question, then open the answer or worked solution.
Ethane, with the molecular formula C2H6, has
(a) 6 covalent bonds
(b) 7 covalent bonds
(c) 8 covalent bonds
(d) 9 covalent bonds
Answer: (b) 7 covalent bonds
Solution: Ethane, with the molecular formula C2H6, has 7 covalent bonds.
Butanone is a four-carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol
Answer: (c) ketone
While cooking, if the bottom of the vessel is getting blackened on the outside, it means that
(a) the food is not cooked completely
(b) the fuel is not burning completely
(c) the fuel is wet
(d) the fuel is burning completely
Answer: (b) the fuel is not burning completely
Solution: While cooking, if the bottom of the vessel is getting blackened on the outside indicates that the fuel is not burning completely.
Explain the nature of the covalent bond using the bond formation in CH3Cl.
Solution: Carbon can neither lose 4 electrons nor gain four electrons as these processes make the system unstable due to the requirement of extra energy. Therefore, CH3Cl completes its octet configuration by sharing its 4 electrons with carbon atoms or with atoms of other elements. Hence, the bonding that exists in CH3Cl is a covalent bonding.
Here, carbon requires 4 electrons to complete its octet, while each hydrogen atom requires one electron to complete its duplet. Also, chlorine requires an electron to complete the octet. Therefore, all of these share electrons, and as a result, carbon forms 3 bonds with hydrogen and one with chlorine.
Draw the electron dot structures for
(a) ethanoic acid
(b) H2 S
(c) propanone
(d) F2
a)
b)
c)
d)
What is a homologous series? Explain with an example.
A homologous series is a series of compounds which has the same functional group. This also contains a similar general formula and chemical properties. Since there is a change in the physical properties, we can say that there would be an increase in molecular size and mass.
For example, methane, ethane, propane, butane, etc., are all part of the alkane homologous series. The general formula of this series is CnH2n+2. Methane CH4 Ethane CH3CH3 Propane CH3CH2CH3 Butane CH3CH2CH2CH3. It can be noticed that there is a difference of −CH2 unit between each successive compound.
Solution coming soon.
How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?
| Ethanol | Ethanoic acid |
| It does not react with sodium hydrogen carbonate | Bubbles and fizzes with sodium hydrogen carbonate |
| A good smell | Smells like vinegar |
| No action in litmus paper | Blue litmus paper to red |
| Burning taste | Sour taste |
Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents, such as ethanol also?
Solution: Micelle formation takes place because of the dirt particles in water and clean water. There are two mediums that are involved: one is pure water, and the other is dirt, also called impurities. The soap also has two mediums:
(i) organic tail
(ii) ionic head
So the organic tail mixes and dissolves with the dirt, whereas the oil or grease and ionic head dissolve and mix with the water. Therefore, when the material to be cleaned is removed from the water, the dirt is taken off by the soap molecules in the water. Hence, the soap cleans by forming closed structures through the mutual repulsion of the micelles (positively charged heads).
Other solvents, such as ethanol, in which sodium salt of fatty acids does not dissolve, so not able to form such micelles.
Why are carbon and its compounds used as fuels for most applications?
Solution: Carbon and its compounds are used as fuels for most applications because they have high calorific values and give out a lot of energy. Most of carbon compounds give a lot of heat and light when burnt in the air.
Explain the formation of scum when hard water is treated with soap.
Solution: Scum is produced from the reaction of hard water with soap. Calcium and magnesium present in the hard water form an insoluble precipitate called scum.