Setting of cement is:(A) exothermic reaction (B) endothermic reaction(C) neither endothermic nor exothermic (D) none of these. Answer Verified Hint: Setting is called as the action of changing from a fluid state to a solid state. During setting when water reacts with cement it liberates heat.

Complete step by step answer: So, the correct answer is Option A. Note: Wet cement is strongly corrosive and can cause severe skin burns and even if they come in contact with mucous membranes it can cause severe eye or respiratory irritation.

Cement is known to a binder that is used in construction sites.Depending upon the ability of the cement to set in the presence of water, cement is divided into:(1). Non-hydraulic cement(2). Hydraulic cementNon – hydraulic cement is that which does not set in wet conditions or under water.

• It sets as it dries and reacts with carbon dioxide in the air.
• It does not get attacked by the chemicals after setting.
• Hydraulic cement is that which sets and becomes adhesive due to a reaction with dry ingredients and water.
• Hydraulic cements consist of a mixture of silicates and oxides.
• The process of formation of cement includes the calcination process of limestone that is calcium carbonate.

The reaction of burning of limestone is:$ } }_ }} \to } }_ }}$From this reaction carbon is removed from limestone and the formation of lime occurs. Then, after this lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate.

The reaction can be written as:$ } }_ }} \to } } }_ }} \\ } }_ }} \to } } }_ }} \\ $Then, lime reacts with aluminium oxide to form tricalcium aluminate.$ } }_ }} }_ }} \to } } }_ }} }_ }}$At last, calcium oxide, aluminium oxide and ferric oxide react together to form cement.$ } }_ }} }_ }} } }_ }} }_ }} \to } } }_ }} }_ }} } }_ }} }_ }}$When cement is mixed with water it starts to set and causes hydration chemical reactions.

The hydration of the constituents occurs slowly and the material solidly and hardens.$CaO.A + 6 O \to 3CaO.A,6 O + \operatorname $ During setting and hardening of cement, some amount of heat is liberated due to hydration and the chemical reactions that occur.As the release of heat takes place.

Which type of change is setting of cement?

During the setting of cement heat is liberated as water reacts with cement so it is an exothermic process.

What is setting process in cement?

What is setting of cement? – When water is mixed with cement, a smooth paste is produced that remains plastic for a short time. During this period, the paste can be disturbed and remixed without injury. As the reaction between water and cement continues, the plasticity of the cement paste is lost. This early period in the hardening of cement is known as ‘Setting of Cement’. Prev Post What are the raw materials used in the manufacturers of Portland cement? Next Post Are there different types of Portland Cement?

Is setting of cement a chemical change?

Setting of cement is:(A) exothermic reaction (B) endothermic reaction(C) neither endothermic nor exothermic (D) none of these. Answer Verified Hint: Setting is called as the action of changing from a fluid state to a solid state. During setting when water reacts with cement it liberates heat.

Complete step by step answer: So, the correct answer is Option A. Note: Wet cement is strongly corrosive and can cause severe skin burns and even if they come in contact with mucous membranes it can cause severe eye or respiratory irritation.

Cement is known to a binder that is used in construction sites.Depending upon the ability of the cement to set in the presence of water, cement is divided into:(1). Non-hydraulic cement(2). Hydraulic cementNon – hydraulic cement is that which does not set in wet conditions or under water.

1. It sets as it dries and reacts with carbon dioxide in the air.
2. It does not get attacked by the chemicals after setting.
3. Hydraulic cement is that which sets and becomes adhesive due to a reaction with dry ingredients and water.
4. Hydraulic cements consist of a mixture of silicates and oxides.
5. The process of formation of cement includes the calcination process of limestone that is calcium carbonate.

The reaction of burning of limestone is:$ } }_ }} \to } }_ }}$From this reaction carbon is removed from limestone and the formation of lime occurs. Then, after this lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate.

The reaction can be written as:$ } }_ }} \to } } }_ }} \\ } }_ }} \to } } }_ }} \\ $Then, lime reacts with aluminium oxide to form tricalcium aluminate.$ } }_ }} }_ }} \to } } }_ }} }_ }}$At last, calcium oxide, aluminium oxide and ferric oxide react together to form cement.$ } }_ }} }_ }} } }_ }} }_ }} \to } } }_ }} }_ }} } }_ }} }_ }}$When cement is mixed with water it starts to set and causes hydration chemical reactions.

The hydration of the constituents occurs slowly and the material solidly and hardens.$CaO.A + 6 O \to 3CaO.A,6 O + \operatorname $ During setting and hardening of cement, some amount of heat is liberated due to hydration and the chemical reactions that occur.As the release of heat takes place.

Which example is physical change?

Table of Contents – When matter changes its observable properties, we can say it has undergone a physical change. Physical change is a type of change where the physical properties of matter change. A change of state of matter, change in colour, odour, solubility, etc. all are examples of physical change. A chemical change is a type of change where the chemical properties of matter change. It is commonly called a chemical reaction. Different substances have different chemical properties. According to this property, substances show variation in their reactivity. The following table shows major differences between physical and chemical changes.

Physical Change	Chemical Change
Change in physical property	Change in physical and chemical property
Reversible process	Irreversible process
Energy is neither absorbed nor evolved	Energy is either absorbed or evolved
No new product formation	The new product is formed

A physical change to a sample of matter occurs when some of the material’s characteristics change but the matter’s identity does not. Physical changes are further divided into two categories: reversible and irreversible. Melting is a reversible physical change since the melted ice cube may be refrozen.

1. Changes in the size or form of matter are examples of physical change.
2. Physical changes include transitions from one state to another, such as from solid to liquid or liquid to gas.
3. Cutting, bending, dissolving, freezing, boiling, and melting are some of the processes that create physical changes.
4. The appearance or shape of matter changes during a physical change, but the kind of matter in the material does not.

A chemical change, on the other hand, results in the formation of at least one new substance with new characteristics. Another sign that a chemical reaction is taking place is a change in hue. This hue shift is the result of a chemical reaction. However, one must exercise caution since occasionally a colour shift is just the result of combining two hues rather than a true change in the composition of the substances in issue. Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin! Select the correct answer and click on the “Finish” buttonCheck your score and answers at the end of the quiz Visit BYJU’S for all Chemistry related queries and study materials

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View Quiz Answers and Analysis : Examples of Physical Changes – Definition, Detailed Explanation about Physical Changes & Chemical Changes

Is this a physical or chemical change?

Contrasting student and scientific views – Student everyday experiences Students have difficulty distinguishing between physical and chemical change, despite formal teaching, and the distinction is somewhat arbitrary. However an understanding of the differences between purely physical processes such as melting, evaporation and boiling and the changes that take place in chemical reactions, particularly the idea that new substances are formed, is important to an understanding of chemistry and students very frequently confuse the two. Pat (recording the group’s notes about a prac): What happened? Kim: It went fizzy. Pat: Did you see any new substances? Kim: Nope. Sam: What shall I write down was formed? Chris: A blue colour. Research: Loughran, Mulhall & Berry (2002) Research shows that students frequently use the term chemical change to describe changes in physical state.

Freezing and boiling are considered to be examples of chemical reactions. This depends on their conception of substance. If students regard ice as a different substance from liquid water they are likely to classify the melting of ice as a chemical change. One study found that 80% of students considered a difference in colour between the reactant and product evidence of chemical change.

Students can consider potassium permanganate (Condy’s crystals) dissolving in water to be a chemical change because of the intense difference in colour. Melting and expansion on heating were also considered to be evidence of chemical change by some students.

Research: Driver, Rushworth & Wood-Robinson (1994) Many students did not appreciate that a chemical change is characterised by the formation of a substance having different properties from the original substance and a considerable proportion of students who did were unable to offer suitable reasons for distinguishing a ‘new’ substance.

Research: Driver, Rushworth & Wood-Robinson (1994) Students may believe that beer frothing is an example of a chemical change or an apple ripening is a physical change. Research: Tsaparlis (2003) Students commonly believe that physical changes are reversible while chemical changes are not.

• Students also frequently believe that the original substance in a chemical reaction vanishes completely and forever.
• A common everyday application of a reversible chemical reaction is the charging and discharging of rechargeable batteries – including car batteries; however students may believe that batteries are a container of stored electricity, rather than of chemicals that react in ways that convert chemical energy into electrical energy.

Other commonly held views are that chemical changes are caused by the mixing of substances/reactants or that heat (which is considered to be some form of material) has to be added. Scientific view In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not.

However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed. The distinction between physical and chemical change is not clear cut. Frequently students are led to believe that a change is either physical or chemical. In fact this should be considered more of a continuum.

For example salt dissolving in water is usually considered to be a physical change, however the chemical species in salt solution (hydrated sodium and chlorine ions) are different from the species in solid salt. Dissolving of instant coffee in water seems to be a physical change but in most cases dissolving is accompanied by an energy change and is probably better considered to be a chemical process even though it is possible to recover the original components by physical means.

• Many examples of materials dissolving (for example, an Alka Seltzer in water, metal in acid and the effect of acid rain on marble and concrete) involve both chemical and physical processes.
• Research: Fensham (1994) Most chemical reactions are reversible although this can be difficult in practice.
• Many junior school science texts state that chemical changes are irreversible while physical changes can be reversed.

Cutting paper into tiny pieces or crushing a rock are obvious physical changes but to restore the original piece of paper or rock is difficult. Rechargeable batteries use one chemical reaction when discharging and recharging involves driving that reaction backwards, turning the products back into the original reactants.

Why is setting time of cement done?

FAQs – What is initial setting time of cement? The initial setting time of concrete is the time when cement paste starts hardening after adding water. It is the time period between the addition of water to cement till the time at 1 mm square section needle fails to penetrate the cement paste, placed in the Vicat’s mold 5mm to 7mm from the bottom of the mold.

What is final setting time of cement? Final setting time is that time period between the time water is added to cement and the time at which 1 mm needle makes an impression on the paste in the mould but 5 mm attachment does not make any impression. What is the need for determining initial and final setting time of cement? Initial setting time is the time when the paste starts losing its plasticity.

The test is important for transportation, placing and compaction of cement concrete. Initial setting time duration is also required to delay the process of hydration or hardening. Final setting time is the time when the paste completely loses its plasticity.It is the time taken for the cement paste or cement concrete to harden sufficiently and attain the shape of the mould in which it is cast.

Is cement setting exothermic?

When cement, water, aggregate, and additives are mixed together, a significant heat increase occurs. This is due to the exothermic process in the reaction between cement and water (called hydration).

Which cement is exothermic?

Hydraulic cements, including Portland cement, set and harden when mixed with water at room temperature Cement Hydration Hydraulic cements, including portland cement, set and harden when mixed with water at room temperature. The reactions that cause setting and hardening are collectively described as exothermic hydration reactions.

The reaction of portland cement compounds with water is exothermic; that is, heat is generated from the reaction. The average is 120 calories per gram during complete hydration of the cement. In normal construction, structural members have relatively high surface-to-volume ratios such that the dissipation of the heat generated is not a problem.

By insulating the forms, this heat can be used as an advantage during cold weather to maintain proper curing temperatures. However for dams, massive foundations, and other mass concrete structures, measures must be taken to reduce or remove heat by proper design and construction methods.

1. This may involve circulating cold water in embedded pipe coils or other cooling means.
2. Another method of controlling heat evolution is to reduce the percentage of compounds with high heat of hydration, such as C 3 A and C 3 S, and use a coarser fineness to produce a Type IV low heat of hydration cement.

Since Type IV is generally no longer available in most locations, Type II and pozzolans or slag are used as a substitute. The use of large aggregate (nominal diameter greater than 150 millimeters) also helps to reduce the cement requirement and consequent heat by reducing the water demand, hence, less cement at the same water cement ratio.

What is an example of an endothermic phase change?

Summary – Fusion, vaporization, and sublimation are endothermic processes, whereas freezing, condensation, and deposition are exothermic processes. Changes of state are examples of phase changes, or phase transitions, All phase changes are accompanied by changes in the energy of a system.

1. Changes from a more-ordered state to a less-ordered state (such as a liquid to a gas) are endothermic,
2. Changes from a less-ordered state to a more-ordered state (such as a liquid to a solid) are always exothermic,
3. The conversion of a solid to a liquid is called fusion (or melting),
4. The energy required to melt 1 mol of a substance is its enthalpy of fusion (Δ H fus ).

The energy change required to vaporize 1 mol of a substance is the enthalpy of vaporization (Δ H vap ). The direct conversion of a solid to a gas is sublimation, The amount of energy needed to sublime 1 mol of a substance is its enthalpy of sublimation (Δ H sub ) and is the sum of the enthalpies of fusion and vaporization.

1. Plots of the temperature of a substance versus heat added or versus heating time at a constant rate of heating are called heating curves,
2. Heating curves relate temperature changes to phase transitions.
3. A superheated liquid, a liquid at a temperature and pressure at which it should be a gas, is not stable.

A cooling curve is not exactly the reverse of the heating curve because many liquids do not freeze at the expected temperature. Instead, they form a supercooled liquid, a metastable liquid phase that exists below the normal melting point. Supercooled liquids usually crystallize on standing, or adding a seed crystal of the same or another substance can induce crystallization.

Is cement reversible or irreversible change?

Hardening of cement is an irreversible change because it can’t be brought back to the powder form.

What is an example of a chemical property change?

Table of Content – Chemical changes happen around us all the time and not just in a chemistry lab. Some chemical change examples in our everyday life are mentioned below.

• Burning of paper and log of wood
• Digestion of food
• Boiling an egg
• Chemical battery usage
• Electroplating a metal
• Baking a cake
• Milk going sour
• Various metabolic reactions that take place in the cells
• Rotting of fruits
• Decomposition of waste
• The explosion of fireworks
• The reaction between,
• Rusting of iron
• Lighting a matchstick

Organic Compounds are complex compounds of carbon in which one or more atoms are covalently linked to atoms of other elements. Some examples of chemical change involving organic compounds are stated below. This is a clear example of a combustion reaction.

Natural gas comprehends methane gas. When methane reacts with oxygen in the atmosphere it produces water and carbon dioxide. Hence, it is an example of chemical change. It involves a series of changes. Fruits consist of ethylene. There is an increase in ethylene production when fruit gets damaged or when it is plucked.

This results in the production of new enzymes which in turn reacts with the chemical present on the fruit. So, the fruit may witness several changes. Some changes are mentioned below.

• The fruit becomes more juicy and soft.
• Due to the breakdown of chlorophyll, the outer skin of fruit changes its colour.
• Aroma emits from ripe fruit.

The reactions of compounds and elements that do not involve are the chemical changes involving inorganic compounds. Some examples of chemical change that involves inorganic compounds are mentioned below. It is an irreversible process. Steel is formed by the addition of several other elements in definite quantities to iron, the basic element being carbon.

This results in the formation of new substances, thus considering it has a chemical change. The properties of the newly formed substances are different from that of iron. Firework consists of metal nitrates thus constituting burning compounds. When a firework is lit, combustion takes place leading to the formation of a new substance with the emission of light and heat.

Thus, it can be considered a chemical change. It deals with the chemistry of the activity and the growth of living organisms. An example of biochemical changes is mentioned below. Photosynthesis is a process that is mainly used by plants to convert light energy into chemical energy.

• 1. Milk turns sour due to
• (a) Conversion of lactose in lactic acid (b) Increased chemical changes (c) Conversion of lactic acid into lactose
• (d) Both A and B
• Ans: (d)

A chemical transition is the result of a chemical reaction, whereas a physical change is when the structure of matter changes, but not the chemical identity. Burning, cooking, rusting and rotting are examples of chemical changes. A chemical transition, also known as a chemical reaction, is a process that transforms one or more substances into one or more new and different substances.

A chemical transformation, in other words, is a chemical reaction involving the rearrangement of atoms. Chemical transition conditions: colour change, precipitate formation, gas formation, smell change, change in temperature. Wood burning is a chemical change when new materials are created that cannot be removed (e.g.

carbon dioxide). For example, if a fireplace burns wood, there is no longer wood but ash. Certain examples include candle burning, iron rusting, cake baking, etc. Chemical change requires a molecular level change to stop it from being reversed because it creates a new substance. Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin! Select the correct answer and click on the “Finish” buttonCheck your score and answers at the end of the quiz Visit BYJU’S for all Chemistry related queries and study materials

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View Quiz Answers and Analysis : Examples of Chemical Change – Definition & Examples with Videos

Which is an example of chemical change?

Examples of Chemical Change – Studying examples of chemical change will help your class conceptualize this topic. Examples of chemical changes include baking soda and vinegar creating carbon dioxide, iron rusting, and wood burning. The body creates a variety of chemical reactions as well, including the metabolization of food and the combination of sugar and saliva creating amylase.

Is hardening of cement a physical or chemical change?

Answer:When the powdered cement particles were exposed to carbon dioxide, it increased the rate of hydration. Hydration was a chemical reaction wherein all the cement molecules react with the water molecules to form their hydration products. After the hydration process, the cement particles also underwent a physical process, called hardening, wherein the product formed a stiff layer that was able to bear higher loads.

What is chemical reaction of cement?

Background – Concrete is made by the combination of cement, water, and aggregate of various sizes to make a workable slurry that has the consistency of a thick milk shake.

Name	Percent by Weight	Chemical Formula
Tricalcium silicate	50%	3Ca0 SiO2
Dicalcium silicate	25%	2Ca0 SiO2
Tricalcium aluminate	10%	3Ca0 Al2 O3
Tetracalcium aluminoferrite	10%	4Ca0 Al2 Fe2 O3
Gypsum	5%	CaSO4 H2O

The binding quality of portland cement paste is due to the chemical reaction between the cement and water, called hydration. Portland cement is not a simple chemical compound, it is a mixture of many compounds. Four of these make up 90% or more of the weight of portland cement: tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.

In addition to these major compounds, several other play important roles in the hydration process. Different types of cement contain the same four major compounds, but in different proportions. The cement in concrete needs water to hydrate and harden. Even though the chemical reactions may be complete at the surface of the concrete, the chemical reactions at the interior of the concrete take much longer to complete.

The strength of the concrete keeps growing as long as the chemical reactions continue. When water is added to cement, the chemical reaction called hydration takes place and contributes to the final concrete product. The calcium silicates contribute most to the strength of concrete.

• Tricalcium silicates are responsible for most of the early strength (first seven days).
• The original dicalcium silicate hydrates, which form more slowly, contribute to the strength of concrete at later stages.
• The following word equations describe the production of concrete.
• Tricalcium silicate + Water (yields) Calcium silicate hydrate + Calcium hydroxide + heat Dicalcium silicate + Water (yields) Calcium silicate hydrate + Calcium hydroxide + heat Of the five chemical reactions important for providing the strength for concrete the above reactions are the most important.

The two calcium silicates, which constitute about 75 percent of the weight of portland cement, react with water to form two new compounds: calcium hydroxide and calcium silicate hydrate. The latter is by far the most important cementing component in concrete.

The engineering properties of concrete—setting and hardening, strength and dimensional stability—depend primarily on calcium silicate hydrate gel. It is the heart of concrete. When concrete sets, its gross volume remains almost unchanged, but hardened concrete contains pores filled with water and air that have no strength.

The strength is in the solid part of the paste, mostly in the calcium silicate hydrate and crystalline phases. The less porous the cement paste, the stronger the concrete. When mixing concrete, therefore, use no more water than is absolutely necessary to make the concrete plastic and workable.

What are the chemical reactions involved in the setting of cement?

Hydraulic cement – Clinker nodules produced by sintering at 1450 °C. By far the most common type of cement is hydraulic cement, which hardens by hydration of the clinker minerals when water is added. Hydraulic cements (such as Portland cement) are made of a mixture of silicates and oxides, the four main mineral phases of the clinker, abbreviated in the cement chemist notation, being: C 3 S: Alite (3CaO·SiO 2 ); C 2 S: Belite (2CaO·SiO 2 ); C 3 A: Tricalcium aluminate (3CaO·Al 2 O 3 ) (historically, and still occasionally, called celite ); C 4 AF: Brownmillerite (4CaO·Al 2 O 3 ·Fe 2 O 3 ).

The silicates are responsible for the cement’s mechanical properties — the tricalcium aluminate and brownmillerite are essential for the formation of the liquid phase during the sintering ( firing ) process of clinker at high temperature in the kiln, The chemistry of these reactions is not completely clear and is still the object of research.

First, the limestone (calcium carbonate) is burned to remove its carbon, producing lime (calcium oxide) in what is known as a calcination reaction. This single chemical reaction is a major emitter of global carbon dioxide emissions, The lime reacts with silicon dioxide to produce dicalcium silicate and tricalcium silicate. The lime also reacts with aluminum oxide to form tricalcium aluminate. In the last step, calcium oxide, aluminum oxide, and ferric oxide react together to form cement.

Which type of change is hardening of cement?

Hardening of cement is an irreversible change because it can’t be brought back to the powder form. Hence, this change cannot be reversed.

Which chemical is used to increase setting time of cement?

Calcium Sulphate (CaSO4) is in the form of Gypsum and its function is to increase the initial setting time of cement.

What type of change is mixing of cement and water?

Water combines with cement to form a paste that binds it together. This paste is altogether a new substance and we can not get back cement and water from the mixture. Therefore, it is an irreversible chemical change.