What are the types of molecules of elements and compounds?
SSC-Science-Part-1-Ch-3 : There are two main types of molecules: those of elements and those of compounds.
Molecules of elements are made up of identical atoms. For example, the oxygen molecule (O2) is made up of two atoms of oxygen.
Molecules of compounds are made up of different atoms that are chemically bonded together. For example, the water molecule (H2O) is made up of two atoms of hydrogen and one atom of oxygen.
There are many other types of molecules, including organic molecules, inorganic molecules, and complex molecules like proteins and DNA. Do you have any other questions about molecules?
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What is meant by valency of elements?
Valency is a measure of the combining capacity of an atom of an element with other atoms when it forms chemical compounds or molecules. It is the number of electrons an atom of an element can donate or accept to form chemical bonds.ssc-science-part-1-ch-3
The valency of an element is determined by the number of electrons in its outermost shell. Specifically, the valency is equal to the number of electrons an atom needs to gain, lose, or share with another atom to attain a stable configuration of eight electrons in its outermost shell. This is known as the octet rule.
For example, the valency of sodium is 1 because it has one electron in its outermost shell and can donate this electron to form a bond with another atom that requires one electron. Similarly, the valency of chlorine is 1 because it has seven electrons in its outermost shell and can accept one electron to attain a stable configuration.
Understanding the valency of an element is important in predicting the types of chemical bonds that an element can form with other elements and in understanding the properties and behavior of different chemical compounds.
What is the requirement for writing molecular formulae of different compounds?How
are the molecular formulae of the compounds written?
To write the molecular formulae of different compounds, we need to know the composition of the elements present in the compound. The molecular formula of a compound shows the number and the type of atoms present in a molecule.ssc-science-part-1-ch-3
To write molecular formulae, we first determine the chemical symbols of the elements that are present in the compound. Then, we use subscripts to indicate the number of atoms of each element in the molecule.
For example, let’s take glucose, whose molecular formula is C6H12O6. This formula indicates that glucose contains six carbon atoms, twelve hydrogen atoms, and six oxygen atoms.
SSC-Science-Part-1-Ch-3 : What are the other uses of silver nitrate in everyday life?
Apart from its medical and industrial applications, silver nitrate has various everyday uses. Some of them are:
- Photography: Silver nitrate is used in black and white film photography to create the silver halide crystals that make up the film’s emulsion.
- Glass staining: Silver nitrate is used to stain glass and impart a yellow color to it.
- Mirror making: Silver nitrate is used in the production of mirrors. It is mixed with other chemicals to create a reflective layer on the glass.
- Jewelry: Silver nitrate is used to create silver jewelry and other decorative items.
- Wart removal: Silver nitrate is sometimes used to remove warts by chemically burning them off.
- Wood staining: Silver nitrate is used to darken wood, giving it a vintage or antique look.
These are some of the everyday uses of silver nitrate. While it is a useful chemical, it’s important to remember that it should be handled with care as it can be hazardous in concentrated doses.
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CaO + H2O Ca(OH)2 + Heat
The chemical equation provided is a balanced equation that represents the reaction between calcium oxide (CaO) and water (H2O) to form calcium hydroxide (Ca(OH)2) and heat.
There is one reactant on each side of the equation. On the left side, we have CaO as the only reactant and on the right side, we have H2O as the only reactant.
So, the number of reactants in this reaction is one on each side. ssc-science-part-1-ch-3
2Mg + O2 2 MgO
The chemical equation provided is a balanced equation that represents the reaction between magnesium (Mg) and oxygen (O2) to form magnesium oxide (MgO).
There are two reactants in this reaction: magnesium (Mg) and oxygen (O2).
NH3 (g)+ HCl (g) NH4Cl(s)
The chemical equation provided is a balanced equation that represents the reaction between ammonia gas (NH3) and hydrogen chloride gas (HCl) to form solid ammonium chloride (NH4Cl).
There are two reactants in this reaction: ammonia gas (NH3) and hydrogen chloride gas (HCl).
Write down the steps in balancing the equation N2(g) + H2(g) NH3(g).
Here are the steps to balance the chemical equation N2(g) + H2(g) NH3(g):
Step 1: Write down the unbalanced equation: N2(g) + H2(g) NH3(g)
Step 2: Count the atoms of each element on both sides of the equation. The equation is currently unbalanced because there are two nitrogen atoms on the left side and only one on the right side, and there are four hydrogen atoms on the left side and only three on the right side.
Step 3: Begin balancing the equation by adding a coefficient in front of NH3. Since there is one nitrogen atom on the right side, we can balance the nitrogen atoms by placing a “2” in front of NH3 to give us:
N2(g) + H2(g) → 2NH3(g)
Step 4: Count the atoms of each element again. There are now two nitrogen atoms on both sides, but there are six hydrogen atoms on the right side and only two on the left side.
Step 5: To balance the hydrogen atoms, we can place a “3” in front of H2 to give us:
N2(g) + 3H2(g) → 2NH3(g)
Step 6: Count the atoms of each element one more time to ensure that the equation is fully balanced. There are now two nitrogen atoms and six hydrogen atoms on both sides of the equation, so it is now balanced.
Therefore, the balanced chemical equation is:
N2(g) + 3H2(g) → 2NH3(g)
Write down a balanced chemical equation for the following reaction
Calcium chloride + Sulfuric acid Calcium sulphate + hydrogen chloride
The balanced chemical equation for the reaction between calcium chloride and sulfuric acid to form calcium sulfate and hydrogen chloride is:
CaCl2 + H2SO4 → CaSO4 + 2HCl
In this balanced equation, one molecule of calcium chloride (CaCl2) reacts with one molecule of sulfuric acid (H2SO4) to produce one molecule of calcium sulfate (CaSO4) and two molecules of hydrogen chloride (2HCl).
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Write down the physical states of reactants and products in following reactions.
SO2 + 2H2S 3S + 2H2O
2Ag + 2HCl 2AgCl + H2
ere are the physical states of reactants and products in the given reactions:
a. SO2 + 2H2S → 3S + 2H2O
- Reactants: SO2 (g), H2S (g)
- Products: S (s), H2O (g)
b. 2Ag + 2HCl → 2AgCl + H2
- Reactants: Ag (s), HCl (aq)
- Products: AgCl (s), H2 (g)
In the reaction (a), SO2 and H2S are both in the gaseous state (g), while the products S and H2O are in the solid (s) and gaseous states (g), respectively.
In the reaction (b), silver (Ag) is in the solid state (s), while hydrochloric acid (HCl) is in the aqueous state (aq). The products, silver chloride (AgCl) and hydrogen (H2), are in the solid (s) and gaseous states (g), respectively.
Is it possible to produce hydrogen by decomposition of water by means of heat, electricity or light ?ssc-science-part-1-ch-3
Yes, it is possible to produce hydrogen gas by decomposing water through a process called electrolysis. Electrolysis involves passing an electric current through water, which causes the water molecules to break down into hydrogen (H2) and oxygen (O2) gases.
The chemical equation for the electrolysis of water is:
2H2O(l) → 2H2(g) + O2(g)
In this reaction, two molecules of water (H2O) are decomposed into two molecules of hydrogen gas (H2) and one molecule of oxygen gas (O2).
Apart from electrolysis, hydrogen gas can also be produced by the thermal decomposition of water (water splitting) at high temperatures. This process is also known as thermolysis or pyrolysis.
However, the amount of energy required to produce hydrogen gas through water splitting is generally much higher than the energy required by other methods such as reforming natural gas. Thus, water splitting is not currently used as a primary method for hydrogen production on a large scale.
Complete the following reactions and give names of the products.
1. CuSO4(aq) + Fe (s) ……….. + ………….
2. CuSO4(aq) + Pb(s) ……….. + ………….
Here are the completed reactions and the names of the products:
- CuSO4(aq) + Fe(s) → FeSO4(aq) + Cu(s)
- The products are iron (II) sulfate (FeSO4) in the aqueous state (aq) and copper (Cu) in the solid state (s).
- CuSO4(aq) + Pb(s) → PbSO4(s) + Cu(s)
- The products are lead (II) sulfate (PbSO4) in the solid state (s) and copper (Cu) in the solid state (s).
What is the difference in the process of dissolution and a chemical reaction ?
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Dissolution and chemical reaction are two different processes that involve the transformation of substances, but they differ in some key aspects.
Dissolution refers to the process by which a solid, liquid, or gas dissolves into a liquid or a gas to form a homogeneous solution. This is typically a physical change, and the dissolved substance retains its chemical identity.
On the other hand, a chemical reaction is a process that involves the breaking and forming of chemical bonds between atoms, molecules, or ions in order to create new substances with new chemical properties. This is typically a chemical change, and the reactants are transformed into products with different chemical identities.ssc-science-part-1-ch-3
So, in summary, the main difference between dissolution and a chemical reaction is that dissolution is a physical process that does not change the chemical identity of the solute, while a chemical reaction involves the formation of new substances with different chemical properties.
What is the difference in the process of dissolution and a chemical reaction ?
Dissolution and chemical reaction are two different processes that involve the transformation of substances, but they differ in some key aspects.
Dissolution refers to the process by which a solid, liquid, or gas dissolves into a liquid or a gas to form a homogeneous solution. This is typically a physical change, and the dissolved substance retains its chemical identity.
ssc-science-part-1-ch-3
On the other hand, a chemical reaction is a process that involves the breaking and forming of chemical bonds between atoms, molecules, or ions in order to create new substances with new chemical properties. This is typically a chemical change, and the reactants are transformed into products with different chemical identities.
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So, in summary, the main difference between dissolution and a chemical reaction is that dissolution is a physical process that does not change the chemical identity of the solute, while a chemical reaction involves the formation of new substances with different chemical properties.
Which is the oxidant used for purification of drinking water?
The most commonly used oxidants for the purification of drinking water are chlorine and ozone. Chlorine is a strong oxidant that is widely used for water disinfection, and it is effective against a wide range of microorganisms, including bacteria, viruses, and protozoa. Chlorine is usually added to water in the form of sodium hypochlorite or calcium hypochlorite.
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Ozone, on the other hand, is a very strong oxidant that is effective against a wide range of waterborne pathogens, including viruses, bacteria, and protozoa. the Ozone is produced by passing air through an electric discharge, and it is then injected into the water. Ozone is a very effective oxidant, but it is more expensive than chlorine, and it requires specialized equipment for its production and injection.
Both chlorine and ozone are effective oxidants for the purification of drinking water, and their use depends on factors such as the quality of the source water, the level of treatment required, and the cost of the treatment process.
Why is potassium permanganate used during cleaning water tanks?
Cleaning water tanks is an important task that ensures the water stored in the tank remains clean and safe for human consumption. Here are some general steps to clean a water tank:ssc-science-part-1-ch-3
- Empty the tank: First, ensure that the water supply to the tank is turned off and then drain the tank completely.
- Remove debris: Remove any debris, sediment, or sludge that may have accumulated at the bottom of the tank. You can use a bucket or a wet and dry vacuum cleaner.
- Scrub the interior: Using a scrub brush and a solution of water and mild detergent, scrub the inside of the tank to remove any remaining debris or dirt.
- Rinse the tank: Rinse the tank thoroughly with clean water to remove any soap residue or dirt.
- Disinfect the tank: Disinfect the tank by adding a solution of water and bleach (1/4 cup of bleach per gallon of water) and letting it sit for about 30 minutes. Then, rinse the tank thoroughly with clean water.
- Refill the tank: Once the tank has been cleaned and disinfected, allow it to dry completely and then refill it with clean water.
It is important to note that the frequency of tank cleaning depends on the quality of the source water and the usage of the tank. It is recommended to clean the tank at least once a year to ensure that the water stored in the tank remains clean and safe for human consumption.ssc-science-part-1-ch-3
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Some more examples of redox reaction are as follows.Identify the reductants and oxidants from them.
SO2 3S + 2H2O
MnO2 + 4 HCl MnCl2 + 2H2O + Cl2
In the first equation, 2H2S is being oxidized to 3S, while SO2 is being reduced to 2H2O. Therefore, H2S is the reductant (or reducing agent), while SO2 is the oxidant (or oxidizing agent).
In the second equation, MnO2 is being reduced to MnCl2, while HCl is being oxidized to Cl2. Therefore, MnO2 is the oxidant, while HCl is the reductant.
If oxidation means losing electrons, what is meant by reduction?
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In a redox reaction, reduction is the process in which an atom, ion, or molecule gains electrons. In other words, reduction involves a decrease in the oxidation number of an atom, ion, or molecule.
The term “reduction” comes from the fact that when an atom gains electrons, its charge becomes more negative (or less positive), and this can be thought of as reducing the amount of positive charge on the atom.
So, reduction is the opposite of oxidation, which involves a loss of electrons and an increase in the oxidation number of an atom, ion, or molecule. Together, these processes make up redox chemistry.
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Write the reaction of formation of Fe2+by reduction Fe3+ by making use of the symbol (e-).
here is the reaction for the formation of Fe2+ by reducing Fe3+ using electrons:
Fe3+ + e- -> Fe2+
This reaction shows that one electron is used to reduce one Fe3+ ion to Fe2+. The electron acts as the reducing agent, while Fe3+ is being oxidized to Fe2+.
The luster of the surface of the aluminium utensils in the house is lost after a few days. Why does this happen?
The loss of luster on the surface of aluminum utensils is due to the formation of a thin layer of aluminum oxide on its surface. When aluminum metal is exposed to air, it reacts with oxygen to form a layer of aluminum oxide on the surface of the metal. This layer of aluminum oxide is very thin, but it is strong, hard, and very resistant to corrosion.
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However, this layer of aluminum oxide can also make the surface of the aluminum utensils appear dull and lose their luster. This is because the aluminum oxide layer is not as reflective as the aluminum metal underneath it, and it scatters light in different directions, making the surface appear dull.
Fortunately, this layer of aluminum oxide can be easily removed by cleaning the utensils with an abrasive cleaner or by using a mixture of vinegar and water. Once this thin layer of oxide is removed, the aluminum utensils will regain their original luster.
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How are the blackened silver utensils and patinated (greenish) brass utensils cleaned?
For blackened silver utensils, you can use a simple home remedy to clean them. Here’s how:
- Line a pan with aluminum foil, shiny side up.
- Add 1 tablespoon of baking soda to the foil-lined pan.
- Pour hot water into the pan.
- Place the blackened silver utensils into the pan, making sure that each piece is touching the foil.
- Allow the silver to soak for a few minutes until the tarnish is lifted.
- Remove the silver from the pan and rinse under cool, running water.
- Dry the silver with a soft cloth.
For patinated brass utensils, you can use the following steps:
- Cut a lemon in half and sprinkle salt on one of the halves.
- Rub the lemon half over the brass surface, squeezing the juice out as you work.
- Let the lemon juice and salt mixture sit on the brass for 5-10 minutes.
- Rinse the brass under warm running water.
- Dry the brass with a soft cloth.
If the brass is heavily tarnished, you might need to repeat the process a few times to remove all of the patina. Once the brass is clean, you can apply a coat of brass polish to help protect it from tarnishing in the future.