Thermal stability of carbonates and nitrates of group-II elements.

WHY DOWN THE GROUP THE THERMAL STABILITY OF CARBONATES AND NITRATES OF GROUP A-II ELEMENTS INCREASE.

The carbonate and nitrates of group A-II elements decomposes on heating. Carbonates decomposes to form corresponding oxides and carbon oxide while nitrates decomposes to form corresponding oxides, nitrogen dioxides and oxygen

                    XCO_3(s)→XO_(s)+CO_2(g)

Decomposition of carbonates where “X” is an group (ii) element

                           2X(NO₃)_2(s)→2XO_(s)+4NO_2(g)+O_2(g)

Decomposition of nitrates where “X” is an group (ii) element

Their thermal stability of carbonates and nitrates of group elements increase down the group. This means that lower member carbonates of group A-II elements are more stable and require more energy to be decompose

REASON

The group A-II of the periodic table have the following elements and their size increases down the group.

After losing the two valance electrons they form M⁺²  ions. The M⁺² ions of these elements have high charge density, a small 2+ ion has a very large charge in a very small volume. Down the group the size of M⁺² ions also increases and charge density decreases. M⁺² ion with high Charge density have high polarizing power than M⁺² ions with low charge density.Cation with high polarizing power distorts the anion easily. In the group A-II of periodic table as we go down the group the polarizing power of group (II) elements decreases and so their distorting effect on the large carbonate ions and nitrates ions get reduced and stability of carbonate and nitrates increases. In short more polarization requires less heat.  So they become thermally more stable. This means that MgCO₃ is thermally less stable than CaCO₃

ENERGETICS OF THE PROCESS

The data in the above table shows that the above reaction becomes more endothermic down the group and thermal stability increases down the group. To explain the cause of increasing endothermic changes down the group we will focus on the enthalpy cycle involving the lattice enthalpies of the metal carbonates and the metal oxides. The amount of heat required to convert one mole of crystal into gaseous component ions is called lattice enthalpy. In BaCO₃ the distance between the center of negative carbonate ion and positive Ba⁺² is greater than the distance in MgCO₃ case. So greater energy is required in case of in case of MgCO₃ to separate into ions having lager lattice energy. The same rule is followed for nitrates.

Caffeine and its effects

CAFFEINE

Caffeine (1,3,7-trimethylxanthine) which is a chemical substance, it is found in coffee, tea mate and other product.

METABOLISM OF CAFFEINE

Caffeine within 1-1.5 h enters into our blood streams from intestine after ingestion. In the liver the metabolism of caffeine take place to form 1-methylxanthine and 1-methyluric acid and the non-metabolized amount of caffeine which is only 1.5% discharge outside of our body through urine. In small children’s of 8-9 months 85% of the ingested caffeine discharge through urine to outside the body.

BLOOD PRESSURE AND CAFFEINE

The research has shown that caffeine can increase the blood pressure (in systolic (5–15mmHg) and/or diastolic (5–10 mmHg)   of caffeine habitual persons especially in elders hypertensive ones. Some research have also shown that in normal adults whose Caffeine regularly does not show a raise in blood pressure.

Lower the risk of cardiovascular disease

Research have also shown that caffeine lower the risk of cardiovascular disease.

Anxiety

Some research shows that the consumption of caffeine in adults causes an increase in anxiety. But there are proof of research which indicates that in normal adult’s caffeine have no such effects.

A FEW USES OF CAFFEINE

1  1)    In sports players uses Caffeine as a stimulating agent.

2 2)  Caffeine creams made of caffeine are used to lessen the redness and itching in dermatitis.

3 3)   Caffeine is also an important part of food items it is present in soft drinks, energy drinks, and other.

RECOMMENDED DOSE OF CAFFEINE

Ingestion of Caffeine doses up to 400 mg per day is considered to be safe for normal adults nearly 4 cup of coffee contain the same amount of caffeine
Ingestion of Caffeine with high doses (>400 mg per day)is consider is good .
.ingestion of caffeine about less than 300 mg in pregnant breast-feeding women is not associated with any adverse major effect. But high dose of caffeine might lead to the chance of miscarriage and other complications.

CONCLUSIONS

From the above discussion we get a result that  moderate consumption of caffeine is not associated mode or performance adverse effect(as general toxicity, cardiovascular effects, effects on bone status and calcium balance) in normal adults and most of these adverse effects linked with ingestion of caffeine in large amount. Those persons which have anxiety disorders should limit their caffeine intake accordingly. The children and reproductive-aged women should take care, not to ingest caffeine more than recommended amount.

Reaction of Halogens with metals

Why halogen form ionic bonds with most metals but covlent   bonds with aluminum and beryllium.

Halogens- metal compounds are mostly ionic in nature

 Reason

1)     There is a high electronegativity difference between halogens and metals.

2)     Secondly halogen have higher electron affinity so negative halide ion X^─ formation is easier.

3)     Thirdly Halogens have high positive standard reduction potential (X₂/2X^─) if we convert this reduction potential into energy term by using the following equation  

             ∆G= ─nFEͦ         n = no of electrons (in this case 2)

                                         F = Faraday constant

Eͦ value decrease down the group and the halide ion X^─  formation energy also decreases.

That’s why most of the iodide are partially covalent and have low melting points than the fluorides

There are certain metals like aluminum and beryllium which farm covalent compounds with halogens

 Reason

 Beryllium in Be⁺² Oxidation state and Aluminum in Al⁺³ state have very small size and that's why they form covalent compound with halogens.

Medicinal value of cannabis its genetic engineering

Medicinal value and Genetic engineering of Cannabis and its cultivation in Pakistan.

Cannabis (Cannabis Sativa) is one of the oldest famous plant which is commonly available in nearly all parts of Pakistan and Afghanistan etc. They were also   extensively used by the chimes and Indian in ancient times.

Cannabis as a Recreational drugs

A drug that is used for enjoyment, or leisure purposes, rather than for medical reasons is called Recreational drugs. These type of drugs modify the perceptions, feelings, and emotions of the user and in a state of consciousness for pleasure is achieved. Cannabis has the same potential and very famous for this special character. Cannabis smoking generate side effects like increased heart rate and fluctuations in blood pressure, euphoria, anxiety, psychomotor retardation.

Cannabis use by Chinese

They were also   extensively used by the chimes and Indian in ancient times. The Chinese prepared paper, Ropes, textiles, string from the fibers obtained from the stem of cannabis plant and used its fruit as food. The Chinese used the cannabis plant for medicinal purposes also.it was used for the treatment of rheumatic pain, malaria, disorders of the female reproductive system, intestinal constipation etc . Even now in this advanced world Chinese physicians recommends cannabis seeds as a laxative to the patients.

                    

 D⁹-tetrahydrocannabinol (D⁹-THC)

D⁹-tetrahydrocannabinol (D⁹-THC) is the main active component of cannabis plant and mostly composed of fatty acids and proteins. The therapeutic effects, of theses fatty acids can be used in atherosclerosis, rheumatoid arthritis, osteoporosis, and other inflammatory diseases.

Western nation’s interest

Now a day’s cannabis has achieved a significant attention in Europe and America. Cannabis has not only applications Medical field but also in a large number of industries like pulp and paper, food products, cosmetics, building materials, textile, and nutritional supplements.

Cannabis Genetic engineering

The western nations have shown a great interest in changing the genetic makeup of the cannabis. The harmful aspects of the modified cannabis have been reduced by genetic engineering and their useful aspects have been improved. The environmental conditional and the soil for the cultivation of cannabis is very suitable in Pakistan.  Keeping in mind the interest of the western nation in cannabis due to its extensive application for pleasure and other medical and industrial uses Pakistan should promote the cultivation of modified cannabis to support its weak economy.

For further reading

1) Brazilian Journal of Psychiatry

Print version ISSN 1516-4446On-line version ISSN 1809-452X

Rev. Bras. Psiquiatr. vol.28 no.2 São Paulo June 2006

2) Li HL. Hallucinogenic plants in Chinese herbals. J Psychodelic Drugs. 1978;10(1):17-26