Chemistry In Daily Life
Class 7 | Science — Chemistry | Unit 4
Class 7 Unit 4 Science
Chemistry in Daily Life
Learning Objectives
- Understand the meaning of Medicines, Antibiotics, Analgesics, Antiseptics, Antihistamines, Antacids and Oral Rehydration Solution (ORS)
- Understands combustion and its types
- Recognizes flame and its structure
Introduction
During the Bangladesh liberation war, Therapy with Oral Rehydration Solution (ORS) in 1971 reduced cholera death rates from 50 percent to 3 percent among thousands of refugees. An Indian doctor, Dilip Mahala Nabis, had to manage the shortage of saline bottles and cope up with the dehydration faced by the refuges. Dr Dilip Mahala Nabis showed the efficacy of ORS in cholera cases among Bangladeshi refugees (1971 to 1972). Further field trial during the cholera epidemic in Manipur attested to its efficacy, ORS has since saved the lives of millions of children around the world.
Look at the above information. What do you infer from this? Now you get the curiosity to know about ORS and its function. Don't you? In addition to this, let us know about some of the common medicines and how do they work.
In the normal healthy intestine, there is a continuous exchange of water through the intestinal wall. Up to 20 liters of water is secreted and very nearly as much is reabsorbed every 24 hours. This mechanism allows the absorption of soluble metabolites into the bloodstream from digested food. However, when a person becomes sick, due to diarrhea, water is expelled and the body is not able to retain the liquid balance. This is called as 'dehydration'. It is not the diarrhea that kills, but the dehydration' resulting from the infection that kills. If more than 10% of the body's fluid is lost death occurs.
Do You Know?
UNICEF or WHO norms the ORS should be prepared as follows:
| Serial Number | New ORS | Gram/Litre percentage | New ORS | Milli mol/litre |
|---|
| 1 | Sodium chloride | 2.6 (12.683%) | Sodium | 75 |
| 2 | Glucose, (anhydrous) | 13.5 (65.854%) | Chloride | 65 |
| 3 | Potassium chloride | 1.5 (7.317%) | Glucose, anhydrous | 75 |
| 4 | Trisodium citrate, (dehydrate) | 2.9 (14.146%) | Potassium | 20 |
| 5 | | | Citrate | 10 |
| Total | | 20.5 (100.00%) | Total Osmolarity | 245 |
4.1 Oral Rehydration Solution (ORS)
ORS (Oral Rehydration Solution) is a special combination of dry salts that is mixed with safe water. It can help to replace the fluids lost due to diarrhea. Vomiting and sweat. In a state of diarrheal disease there is imbalance and much more water is secreted than reabsorbed causing a net loss to the body which can be as high as several liters a day. In addition to water loss, sodium and potassium are also lost. Certain concentration of sodium (Na) is needed for proper functioning of the body. For example, only with adequate sodium concentration in the intestinal wall, water can be absorbed by it through a process known as osmosis. If there is inadequate salt in the intestinal wall the body will not be able to absorb water. The saline bottle directly transfers water and sodium into the blood stream. However, for the saline water is administered through mouth, intestinal wall, is a not able to absorb neither water nor sodium. Dr Dilip Mahala Nabis found that if glucose (that means sugar), is added to the salt solution, then all the three water, sodium and glucose are absorbed by the body. During diarrhea the intestine is still able to absorb glucose molecules. Thus, the ORS solution uses the glucose molecules to enable the sodium to be is carried through by a cotransport coupling mechanism. ORS is an effective treatment for 90 to 95 percent of patients suffering from diarrhea, regardless of the cause. As the water is replaced balance is attained saving the patience in most cases. Let us see homely made of ORS, be very careful to mix 6 level teaspoons of sugar and half level teaspoon of salt dissolved in 1 liter of clean water. Too much sugar can make diarrhea worse. Too much salt can be extremely harmful to the child. Making the mixture a little too diluted (with more than 1 liter of clean water) is not harmful. Through the process of osmosis, the salts and sugars pull water into your bloodstream and speed up rehydration.
4.2 Antacid
Acidity is a set of symptoms caused by excess production of acid by the gastric glands of the stomach. Your stomach naturally produces gastric or hydrochloric acid (HCl) to help digest and break down food. Acidity issues arise when there is excess production of this acid due to triggers such as acidic foods, spicy food, alcohol, dehydration and stress. When acidity occurs, the excess acid may move up from your stomach to your esophagus. The lining of your stomach with a pH of 1 to 3 is designed as such to withstand a high acidic environment. When we have acidity or heartburn, we are administered a class of medicines known as antacids. They are actually weak bases. As learned in chemistry, when a base is mixed with an acid a neutralization reaction occurs. When antacids are consumed, it creates a chemical reaction in the stomach lowering the acidity and makes the digestive acids less corrosive and damaging. Most of the common antacids are Sodium Bicarbonate, Calcium Carbonate, Magnesium Hydroxide, Magnesium Carbonate and Aluminum Hydroxide. The chemical reaction created when Magnesium Hydroxide neutralizes HCI in the stomach and intestine.
4.3 Antibiotics
Ages ago, there was a time where even a small infected wound can cause death in human beings. The discovery of antibiotics changed all. Now armed with antibiotics, many deadly infectious diseases can be tackled, which once meant to cause serious illness and death. The discovery of antibiotics was an accident, which happened in 1928 while a British bacteriologist, Dr. Alexander Fleming was involved in research on staphylococcus bacteria. This bacterium was meant to cause deadly diseases such as pneumonia, sour throat, etcetera. The discovery happened while he was culturing the bacteria on a nutrient agar media in a Petri dish. He went on a holiday carelessly leaving the dish in his laboratory table without cleaning and sterilization. After several days, when he returned back, he observed the growth of mould (kind of common fungus, which grows on stale bread or cheese.) on a part of the Petri dish. He also observed that there was no bacterial growth surrounding the mould, which indicated that something in the mould had prevented the growth of bacteria in the culture medium. On further research, Fleming identified that the "mold juice" was capable of killing a wide variety of harmful bacteria, such as streptococcus, meningococcus and diphtheria bacillus. And that was how the world's first antibiotic – penicillin – was discovered. Fleming named the mould penicillium notatum, from which the antibiotic penicillin was isolated. However, Fleming was not the first using moulds and other living microorganisms to treat infections. Thousands of years ago, the ancient Egyptians, had used mouldy bread to treat infected wounds. Similar practices were observed among ancient Greeks, Serbians and even among Indians. While these were perhaps partially effective, their efficacy is nowhere near the modern antibiotics. Naturally, many microorganisms and plants synthesize chemicals which are toxic in nature to protect them from invading organisms. The biosynthesized chemicals isolated from the plants or microorganisms and used as medicines against infectious diseases. These substances were called as antibiotics. Example: Chloramphenicol's, tetracyclines, Penicillin derivatives, cephalosporins and their derivatives. Today, many infectious diseases in the world are rare due to the advancement in antibiotic research.
Do You Know?
Antibiotics don't work for viruses like cold and the flu. However, the overuse of antibiotics makes it inactive or less effective. Antibiotic resistance is defined as the ability of the microorganisms to resist the effects of an antibiotic to which they were once sensitive. Thus, the antibiotics become less effective and we are forced to either consume a larger dose or shifting towards the use of other virulent variants of antibiotics. Thus, the research on antibiotics is of great importance to combat the virulent and mutated microorganisms.
4.4 Analgesics
Injury, burn, pressure from sharp objects and other conditions cause pain in our body. The unpleasant feeling may be a burning sensation in the tissue around the injury, throbbing headache or ache of arthritis. Back pain, neck pain, joint pain, headaches, pain from nerve damage, pain from an injury and pain related to diseases are some of the most common pains. The unpleasant emotion of 'pain' is created in the brain and not at the spot of the injury. If the pain is severe, say from burn, the impulse sent to brain trigger immediate response. Reacting to the signal from the brain, muscle pulls our hand from the fire. Reacting to the message received from the pain spot, the brain sends back messages that initiate healing process. It can trigger to release pain suppressing chemical and additional flow of additional white blood cells and platelets to help repair tissue at an injury site. Analgesics or pain killers are the pain suppressing chemicals released by the body. They suppress the feeling of 'pain'. These analgesics drug selectively relieves pain by acting either in (Central Nerves System.) or on peripheral pain mechanism, without significantly altering consciousness. When we are affected by fever, often we are administered Paracetamol. Paracetamol interact with the receptors and reduce the intensity of pain signals to the brain, also suppresses the release of substances, called prostaglandins that increase pain and body temperature.
Do You Know?
Anesthetics
The first local anesthetic was cocaine was isolated from coca leaves by Albert Niemannin Germany, 1860
Traditional anti-inflammatory agents
Peppermint, Catnip
These are classified as follows:
1. Non-narcotic (Non additive) analgesics Example Aspirin
2. Narcotic drugs Example codeine
4.5 Antipyretic
In normal course our body temperature ranges from 98.4 to 98.6 degrees Fahrenheit. When the temperature goes above this level it is called fever. Most common cause of fever is infection. Bacteria and virus cannot thrive above a certain temperature. To defend the invading virus and bacteria the immunity system increases the body temperature. Once infection is sensed, the immune system releases a chemical called pyrogen. These pyrogens released into bloodstream reaches the hypothalamus, present at the basal part of the brain. The function of Hypothalamus is to control the body temperature. Sensing the pyrogens, hypothalamus increases the body temperature by releasing a chemical called prostaglandin. Normally little fever is good as it helps to arrest the growth of infection. However, if the internal body temperature exceeds 105 degree Fahrenheit this may cause damage to our body protein and the brain may experience seizures and delirium. The prolonged high fever may also cause death. Antipyretics (anti against and pyretic Feverish) are chemical substances that reduce fever. They suppress the release of prostaglandin and reduce fever. The most common and well known anti pyretic is paracetamol. Other antipyretics and anti-inflammatory agents include Aspirin, Ibuprofen, Diclofenac.
4.6 Antiseptic
Antiseptics are substances applied to the exterior of a body that kill or inhibit microbes and infective agents. Antiseptics can be effective against one or a combination of bacteria, fungi, viruses or other microorganisms.
Do You Know?
Dettol Mixture of chloroxylenol and terpinol
Tincture Iodine Plus 2 to 3 percent alcohol Water mixture
Soap, Iodoform, phenolic solutions, ethanol, Boric acid are examples.
Natural antiseptics
1. Garlic, 2. Turmeric, 3. Aloe vera, 4. Onion, 5. radish
Difference between Antiseptic and Disinfectants
| Antiseptic | Disinfectants |
|---|
| 1. All antiseptic are disinfectants. | All disinfectants are not antiseptic |
| 2. It can be applied on the live tissues, For example skin or Mucous | It can be applying on in animate object, For example- Surface, lab working tables, floor. |
4.7 Antihistamine
Anti histamines are defined as drugs that combat the histamine in the body that are used for treating allergic reactions and cold symptoms. Histamine is a chemical messenger involved in number of complex biological reactions. When a foreign body such as pollens enters the body, the immune system believes those substances to be harmful and generates the release of histamine. When histamine is released, it will interact with the histamine receptors on the cell surface or within a target cell and cause changes in the bodily functions. This stimulates many smooth muscles to contract, such as gastrointestinal tract and bronchi. In certain smooth muscles, they cause relaxation of blood capillaries which increase the flow of lymph and its protein content and lead to the formation of edema (redness and rashes). Antihistamines or histamine receptor antagonists oppose selectively all the pharmacological effects of histamines. For Example, Diphenhydramine, chlorpheniramine, cimetidine. The adverse effects of antihistaminic are mouth dryness and sleepiness.
Medicine
Medicines are used to treat the disease and to improve our health. "Diagnose the disease and understand its seeds. Identify the cause and make sure it succeeds". Medicine us the science or practice of the diagnosis, treatment, and prevention of disease. There are many ways to intake the medicine.
1. Oral use
2. External use
3. Injections (Intra muscular or Intra venous)
The medicines we take treat our disease and lead us to a good health. The above picture explains instructions to use medicines safely.
Always use medicines safely!
• I know I should never take any medicine that isn't meant for me.
• I know medicine can be dangerous if you take the wrong amount. It tells you on the label how much to take.
• I only take medicines when a grown up I trust gives them to me
• I know medicines are NOT sweets and that they can be harmful
• I know it is important to store medicines out of reach of younger children.
Combustion
Can you guess what is common in rusting or iron, burning coal and the flame of candle? They all undergo a chemical reaction known as combustion. Combustion is a chemical reaction that occurs in the presence of a fuel and an oxidizing agent that produces energy, usually in the form of heat and light. What we call as 'burning' is really a combustion reaction. In fact, combustion is one of the first chemical reactions intentionally harnessed by humans. Any reaction that involves reaction with oxygen is called oxidation reaction. In the combustion of hydrocarbon with oxygen, typically carbon dioxide and water are produced.
Chemical Equation: CH₄ + 2O₂ → CO₂ + 2H₂O + Heat energy
Hydrocarbon + Oxygen → Carbon dioxide + Water
All combustion reactions are exothermic; that is, they release heat.
Ignition Temperature
The minimum temperature at which a substance catches fire, and burns is called its ignition temperature. A substance will not catch fire and burn if its temperature is lower than its ignition temperature. Different substances have different ignition temperatures. Substances which have very low ignition temperature and can easily catch fire with a flame are called inflammable substances. Example. Petrol. Alcohol, LPG (Liquefied Petroleum Gas), CNG (Compressed Natural Gas). etcetera.
Flame
Flame is actually a chemical reaction. To be specific, the flame is a mixture of gases (vaporized fuel, oxygen, carbon dioxide, carbon monoxide, water vapor, and many volatile materials.) and so is matter. The light and heat produced by the flame is energy, not matter. But fire is a matter.
Fact
Chemical Reaction in Ignition
Oxygen + Heat + Fuel → Fire
Which is the festival of light? What is the speciality of that festival? Yes. We will light more lamps to decorate the houses. Wont we? Now how do the lights glow? Yes, with flame. Here is an experiment with colorful flame:
White flame indicates presence of Epsom salt (MgSO₄)
Violet flame indicates presence of Lithium Chloride
Indigo flame indicates the presence of Potassium Chloride
Blue flame indicates the presence of Bleaching powder
Green flame indicates the presence of Borax powder
Yellow flame indicates the presence of Calcium chloride
Orange flame indicates the presence of Table salt
Red flame indicates the presence of Strontium chloride
Flame Definition
Flame is a zone of combustions of a combustible substance. Substances which vaporize during burning produce flames. Example Wax, Kerosene etcetera. Substances which do not vaporize during burning do not produce flames. Example. coal
Structure of a Candle flame
A candle flame has three main zones, they are:
1. The outer zone complete combustion of the fuel takes place and the color of the flame is blue and is the hottest part of the flame. It is the non-luminous part of the flame.
2. The middle zone partial combustions of the fuel takes place and the color of the flame is yellow and is moderately hot part of the flame. It is the luminous part of the flame.
3. The inner zone There are unburnt vapors of the fuel and the color is black and is least hot part.
Finger inside the same Why is the candle same straight?
Do You Know?
A candle flame is caused by vapour burning above the candle. This burning vapour is hotter than the surrounding air and is therefore less dense. So, by the principle of convection, it "rises" so the flame is always upwards
Calorific value of different fuels
| Fuel | Calorific Value (kJ/kg) |
|---|
| Cow dung cake | 6000 to 8000 |
| Wood | 17000 to 22000 |
| Coal | 25000 to 33000 |
| Petrol | 45000 |
| Kerosene | 45000 |
| Diesel | 450000 |
| Methane | 500000 |
| CNG | 50000 |
| LPG | 55000 |
| Biogas | 35000 to 40000 |
| Hydrogen | 1500000 |
The amount of heat energy produced on complete combustion of 1kg of fuel is called its calorific value. The calorific value of a fuel is expressed in a unit called kilo joule per kg (kJ/kg)
Formula: Calorific value = Heat produced / Amount of fuel used for burning (in kJ/kg)
Example: If 4.5kg of fuel is completely burnt and the amount of heat produced stands measured at 180,000 kJ what is its calorific value.
Calorific value = 180,000 / 4.5 = 40,000 kJ/kg
Types of combustion
There are three main types of combustion. They are:
1. Rapid combustion: It is a combustion process in which a substance burns rapidly and produces heat and light with the help of external heat. Example. Burning of LPG.
2. Spontaneous combustion: It is a process in which a light without the help of external heat. example. Phosphorus burns spontaneously at room temperature.
3. Explosion: It is a type of combustion in which a substance burns suddenly and produces heat, light and sound with the help of heat or pressure. Example. Explosion of crackers
Environmental impacts:
CARBON MONOXIDE Leads to respiratory problem
CARBON DIOXIDE is responsible for Global warming
SO₂ or NO₂ are responsible for Acid Rain
More environmental impacts
Remedies
Activity
What happens when you add with these chemicals? Sugar + Potassium permanganate + Glycerin.
Characteristics of good fuel
- Readily available
- Cheap
- Easy transport and store
- Burns at moderate rate
- Produce large amount of heat
- Do not leave behind any undesirable substances
- Does not cause pollution
Slow combustion
Slow combustion is a form of combustion which takes place at low temperatures. Respiration is an example of slow combustion.
The fire triangle
The conditions necessary for producing fire are:
1. Fuel
2. Air (to supply oxygen)
3. Heat (to raise the temperature of the fuel beyond its ignition temperature)
Fire can be controlled by removing any one or more of these conditions.
Fire extinguisher
A fire extinguisher cut off the supply of Air or bring down the temperature of the fuel or both and controls the fire. Portable fire extinguishers apply an extinguishing agent that will either cool burning fuel, displace or remove oxygen, or stop the chemical reaction so fire cannot continue to burn. When the candle of an extinguisher is compressed, it opens and inner canister of high-pressure gases forces the extinguishing agent from the main cylinder through a siphon tube and out the nozzle. A fire extinguisher works much like a can of hair spray.
Types of fire extinguisher
The most common types of fire extinguishers are:
1. Air pressurized water extinguishers
2. Carbon-di-oxide extinguishers
3. Dry chemical powder extinguishers
The different types of extinguisher tackle different types of fire
| Type | Class A Combustible materials (paper and wood) | Class B Flammable Liquids (paint and petrol) | Class C Flammable Gases (butane and methane) | Class D Flammable metals (lithium and potassium) | Electrical Equipment (computer and generators) | Class F Deep fat fryers (chip pans) | Comments |
|---|
| Water | It will work | It won't work | It won't work | It won't work | It won't work | It won't work | Do not use on liquid or electric fires |
| Foam | It will work | It will work | It won't work | It won't work | It won't work | It won't work | Not suited to domestic use |
| Dry powder | It will work | It will work | It will work | It will work | It will work | It won't work | Can be used safely up to 1000 volts |
| Carbon dioxide | It won't work | It will work | It won't work | It won't work | It will work | It won't work | Safe on both high and low voltage |
| Wet chemical | It will work | It won't work | It won't work | It won't work | It won't work | It will work | Use on extremely high temperatures |
Fire extinguishers can be broadly classified into five types:
1. Water 2. Foam 3. Dry Powder 4. CARBON DIOXIDE 5. Wet Chemical.
The classes of fire
There are five classes of fire: Class B, Class A, Class C, Class D, and Class E.
Class A fires Combustible materials: caused by flammable solids, such as wood, paper, and fabric.
Class B fires Flammable liquids: such as petrol, turpentine or paint
Class C fires Flammable gases: like hydrogen, butane or methane
Class D fires Combustible metals: chemicals such as magnesium, aluminum or potassium
Class E fires Typically a chip-pan fire Electrical fires Electrical equipment: once the electrical item is removed, the fire changes class
Points to remember
- Oral Rehydration Solution (ORS) is a mixture of electrolytes, sugar, and water taken by mouth to absorb water and electrolytes in the body and properly restore the electrolyte and find balance lost by excessive sweating, vomiting or diarrhea.
- ORS is an effective treatment for 90 to 95 percent of patients suffering from diarrhea, regardless of the cause.
- Antacid is one that neutralizes stomach acid.
- Medications, drugs, substances used to treat and cure diseases, and to promote health.
- Some microorganisms and plants produce their own toxic substances. These substances those help to destroy other living things are called as antibiotics.
- The chemical process in which a substance reacts with oxygen to produce heat is called combustion.
- Flame is a zone of combustion of a combustible substance. Substances which vaporize during burning produce flames. Examples Wax, Kerosene.
- The minimum temperature at which a substance catches fire, and burns is called its ignition temperature.
- The amount of heat energy produced on complete combustions of 1kilogram of fuel is called its calorific value.
- A fire extinguisher cut off the supply of air or bring down the temperature of the fuel or both and controls the fire.
EVALUATION
Exercise 1. Choose the correct answers
1. A drug effective in the treatment of pneumonia, and bronchitis, is ____
a. Streptomycin b. Chloramphenicol c. Penicillin d. Sulphaguanidine
2. Aspirin is ____
a. Antibiotic b. Antipyretic c. Sedative d. Psychedelic
3. ____ are that neutralize stomach acid.
a. Antacid b. Antipyretic c. Analgesic d. Antihistaminic
4. The lowest temperature at which a substance catches the fire is called its ____
a. Boiling point b. Melting point c. Critical temperature d. Ignition temperature
5. Which is the hottest part in the flame of candle ____
a. Blue b. Yellow c. Black d. Way part Exercise 2. Fill in the blanks
1. Penicillin was first discovered by
2. World ORS Day is
3. Combustion is a chemical reaction in which and substance react with
4. In the presence of water, the ignition temperature of paper is
5. Fire produced by oil cannot be controlled by
Exercise 3. True or False
If False give the correct answer
1. Antibiotics does work for viruses like cold and Flu. 2. Analgesics are the substances that lower the temperature during fever. 3. All fuels form flame. 4. Oxygen is necessary for combustion 5. Burning wood and coal causes pollution of air. Exercise 4. Match the following questions
| 1. Antipyretic | |
| 2. Analgesic | |
| 3. Antacid | |
| 4. Phosphorus | |
| 5. Carbon di oxide | |
Options: reduce pain, reduce body temperature, spontaneous combustion, ORS Solution, leads to respiratory problem
Exercise 5. Analogy
1. Inner zone of flame: , outer zone of flame:
2. Tincture: , histamine:
Exercise 6. Very short answer
1. First viral disease detected in human being was: ______ (Yellow fever or dengue fever)
2. ______, ______, ______ are called greenhouse gases (Fleming or lenis pastor)
3. Name a substance which can be used as an antiseptic as well as disinfectant?
4. What are the main constituents of Dettol?
5. Name the unit in which the calorific value of a fuel is expressed?
6. How many types of combustion are there?
7. What are the essential requirements for producing fire?
Exercise 7. Short Answer Questions
1. Why should not medicines be taken without consulting doctors?
2. Why do antiseptics differ from disinfectants? Give one example of each.
3. What is ignition temperature?
4. If 4.5 kilogram of fuel is completely burnt and amount of heat produced stands measured at 1,80,000 KJ what is the calorific value.
Exercise 8. Answer in Detail
1. Explain briefly about antibiotic and analgesic?
2. Make labeled diagram of a candle flame
Exercise 9. Picture based question
Arul and Aakash were doing an experiment in which water was to be heated in a beaker. Arul kept the beaker near the wick in the yellow part of candle flame. Aakash kept the beaker in the outer most part to the flame. Whose water will get heated in a shorter time?
ICT CORNER
CHEMISTRY IN DAILY LIFE
Explore the activity to know about Flame test.
PROCEDURE:
Step 1: Use the URL or scan the QR code to open the activity page.
Step 2: Use the platinum wire to scoop up chemicals, and then put them in the flame to see how each chemical changes the flame's colour.
Step 3: Press the space bar to select the new chemical.
Chemistry in daily life URL: https://scratch.mit.edu/projects/138778000
📝 Summary
- Dr. Dilip Mahala Nabis developed ORS therapy during the Bangladesh liberation war in 1971, reducing cholera death rates from 50% to 3% among refugees and later proving its efficacy during cholera epidemic in Manipur.
- Dehydration occurs when the body loses more than 10% of its fluid during diarrhea, disrupting the normal 20 liters of water exchange in the intestine every 24 hours, and it is dehydration that kills, not the diarrhea itself.
- ORS is a special combination of dry salts mixed with safe water that helps replace fluids lost due to diarrhea, vomiting and sweat by maintaining proper sodium concentration needed for water absorption through osmosis.
- The key discovery was that adding glucose to salt solution enables the body to absorb water, sodium and glucose together through a cotransport coupling mechanism, as the intestine can still absorb glucose molecules during diarrhea.
- ORS is an effective treatment for 90 to 95 percent of patients suffering from diarrhea regardless of the cause, and follows specific UNICEF/WHO preparation norms with precise measurements of sodium chloride, glucose, potassium chloride and trisodium citrate.