Provide the electron dot structure for CO2:
Provide electron dot structure for a molecule of Sulphur containing eight atoms:
Provide the structural isomers for pentane.
Describe two properties of carbon and give reasons to why there are large number of carbon compounds are around us.
- Carbon has six valence electrons which is actually a high number of valency.
- Covalent bonding happens easy with carbon atoms and numerous others such as oxygen, chlorine, nitrogen, Sulphur, hydrogen and etc.
Due to these two properties, carbon has a higher number of organic compounds around us.
Provide the electron dot structure and formula for Cyclopentane:
Provide the structures for the compounds provided below:
- Ethanoic Acid
Name the following compounds:
Give reason to why the reaction of ethanol to ethanoic acid is an oxidation reaction.
As shown in the reaction: since oxygen is added in this reaction, the change from ethanol to ethanoic acid is known to be an oxidation reaction.
Why is the burnt mixture of oxygen and ethyne used for welding rather than that of ethyne and air?
The production of heat is very important for welding metals. When oxygen and ethyne is burnt, it burns completely and produces a higher temperature than air and ethyne. Oxygen and ethyne produce very hot blue flame but the mixture of air and ethyne gives out a sooty flame which means that there are unburnt particles resulting in lesser heat.
What are oxidizing agents?
When a substance gains electrons from a redox reaction whilst the oxidation number also reduces, it is known as an oxidizing agent.
Using bond formation of Methyl Chloride (CH3Cl), explain the basis of covalent bonding.
Methyl chloride consists of:
- One carbon atom
- Three hydrogen atoms
- One chlorine atom
Carbon atom, hydrogen atom, chlorine atom has four, one and seven valence electrons respectively where carbon shares four of its valence electrons with the three-hydrogen atoms and one chlorine atom. Therefore, it forms methyl chloride as shown in the chemical equation above.
In the dot structure, it can be seen that there are four shared electrons between carbon and the other atoms. In the reaction, each of the shared pairs are considered as one single covalent bond. Hence, methyl chloride is known to have four single covalent bonds.
Draw the electron dot structure for the following:
- Ethanoic acid
Write down the meaning and explanation of homologous series.
It is a series of compounds, which has the same functional group. This also contains similar general formula and chemical properties. Since there is change in the physical properties, we can say that there would be an increase in the molecular size and mass.
Using their physical and chemical properties, differentiate ethanol from ethanoic acid.
|Does not react with sodium hydrogencarbonate||Bubbles and fizzes with hydrogencarbonate|
|A good smell||Smells like vinegar|
|No action in litmus paper||Blue litmus paper to red|
|Burning taste||Sour taste|
State the reason as to why there is micelle formation when soap is added to water.
The reason for the micelle formation is because of the dirt particles in water and clean water. There are two mediums that are involved: one is pure water and the other being dirt (also called as impurities). The soap also has two mediums: (i) organic tail and (ii) ionic head. So the organic tail mixes and dissolves with the dirt whereas the oil or grease and ionic head dissolves and mixes 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 by mutual repulsion of the micelles (positively charged heads).
Explain why carbons and its compounds are used as fuels.
Because, carbon and it’s compounds burn in air and also give out a lot of energy.
Why is scrum produced when hard water is treated with soap?
Scrum is produced from hard water reacting with soap because a soap is wasted from reacting with calcium and the magnesium ions from the hard water. This wasted reaction then forms an insoluble precipitate that sticks as a white layer.
What will be the color change when soap is tested with red litmus paper?
Soap is a base and it will turn red litmus paper to blue.
Define hydrogenation and write about its industrial application.
Hydrogenation is a process or a chemical reaction between hydrogen and other compounds. It is usually done in presence of catalysts: for example nickel, palladium or platinum. Hydrogenation is used mainly to reduce or saturate organic compounds.
Provide a chemical test that could be used to differentiate between cooking oil and butter. Explain the steps to carry out the test.
The test that could be used is bromine water test.
- Add little bromine water to cooking oil
- In a different test tube, add bromine water to butter
If decolorizing happens, then it is considered an unsaturated compound and therefore, it is cooking oil. In addition, the test tube that does not decolorize is considered to be the saturated compound which is the butter.
Can you check if the water is hard using a detergent?
That is not possible because of the formation of lather when detergent is mixed with water.
Why is beating or agitation necessary in order to get clean clothes?
Clothes need to be beaten or agitated so that the soap micelles can trap the oil, grease or any other impurities that have to be removed. When they are being beaten or agitated, the particles are removed from the clothes’ surfaces and go into the water, thus cleaning the clothes.
Explain the process of cleansing action of a soap.
There are so many impurities and dirt mixed in water, and most of all those dirt do not dissolve in the water. Soap molecules is a combination of salts such as sodium or potassium. The molecules are of long chain of carboxylic acids. So, when the carbon chain has dissolved in oil and ionic end has dissolved in the water, the soap starts cleansing and trapping the dirt. When this happens, the soap molecules forms structures that are called as micelles. One end of the micelle is used for capturing the oil droplets and then the other end being the ionic faces. This will then form an emulsion in water and help in dissolving the dirt or impurities when the clothes are washed.
The soap molecules have different properties at different ends. The first end being the hydrophilic end which dissolves in the water and is attracted towards the water and the second one being the hydrophobic end which is dissolved in the hydrocarbons and is repulsive to water. The hydrophobic tail aligns itself along the surface of water because it is not soluble in the water.