Main points in Language of chemistry Flashcards by reshma raju

Define chemical reaction.

Any chemical change in matter which involves its transformation into one or more new substances which also involves the transfer of energy.

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Define reactants.

Substances which undergo chemical change.

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Define products.

Substances that are formed after chemical change.

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What happens to the atoms during a chemical reaction?

The atoms of reacting molecules rearrange themselves to form one or more new substances that can neither be created or destroyed.
(or)
The bond will break.
Rearrangement of molecules
New bond will form.

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Define word equation.

When we write the names of the products and reactants to express a chemical reaction is called word equation.

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Sodium oxide reacts chemically with water to give…

Sodium hydroxide.

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Upon heating of mercuric oxide __________ is formed.

Mercury and oxygen

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Potassium chlorate is a ______ that changes into __________on heating with the help of _____________ a catalyst.

compound,
potassium chloride and oxygen
Manganese dioxide

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Sodium carbonate a _____________ added to dilute hydrochloric acid becomes ____________________________________

white solid
Sodium chloride+ Water+ Carbon dioxide.

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What are the characteristics of occurrence in a chemical reaction?

-Change in color
-Evolution of gas
-Formation of precipitate
-Change of state
-Change of smell
-Change of energy

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Iron + Copper sulphate (_________color) ————————-) ___________

blue color
Iron sulphate (light green)+Copper(reddish brown)

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Sugar(white solid) in the presence of heat becomes………

sugar charcoal and water vapor.

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Copper carbonate (green solid) in the presence of heat becomes…….

copper oxide +Carbon dioxide.

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What color is copper sulphate? Is it a solid?

Blue , no it is a solution.

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What color is iron sulphate? Is it a solid?

Light green, no it is a solution.

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What color is copper? Is it a solid?

reddish brown, yes.

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What color is sugar ?Sugar charcoal?

white. Black.

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What color is copper carbonate ?Is it a solid?

Green. Yes.

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What color is copper oxide? Is it a solid?

Black. Yes.

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Zinc+ Dilute hydrochloric acid gives.

Zinc chloride+ Hydrogen.

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What do you observe when you mix baking soda and vinegar?

Strong effervescence .

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Baking soda + vinegar gives.

Sodium acetate+ Water+ Carbon dioxide.

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Potassium iodide + Lead acetate —————)

Lead iodide+ Potassium acetate.

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What gas is evolved when Zinc is mixed with Dilute hydrochloric acid?

Hydrogen.

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What gas is evolved when you mix baking soda and vinegar?

Carbon dioxide.

Define effervescence.

The bubble formation during a chemical reaction that is due to the evolution of gas.

Barium chloride(solution)+ sodium sulphate(solution) gives..........

Barium sulphate(white precipitate) and sodium chloride(solution).

True or false: Reactants and products are impure substances

False.

Barium chloride is a _______________ (solution/ precipitate). Sodium sulphate is a ______________(solution/ precipitate). Sodium chloride is a _______________(solution/ precipitate). Barium sulphate is a _______________(solution/ precipitate).

Barium chloride is a solution. Sodium sulphate is a solution. Sodium chloride is a solution Barium sulphate is a white precipitate.

What do you observe when potassium iodide solution is added to lead acetate solution?

A yellow precipitate called lead iodide is formed.

Potassium iodide is a _______________ (solution/ precipitate). Lead acetate is a ______________(solution/ precipitate). Lead iodide is a _______________(solution/ precipitate). Potassium acetate is a _______________(solution/ precipitate).

Potassium iodide is a solution. Lead acetate is a solution. Lead iodide is a yellow precipitate. Potassium acetate is a solution.

Hydrogen(solid/liquid or gas)+ Oxygen(solid/liquid or gas)-------)

H-gas O-gas Water-liquid

What do you observe when: Conc. hydrochloric acid+ Ammonia solution

Dense white fumes are observed due to production o ammonium chloride.

Conc. hydrochloric acid+ Ammonia solution-------)

Ammonium chloride

Name the state: Conc. Hydrochloric acid- Ammonia solution- Ammonium chloride-

Conc. Hydrochloric acid-Liquid Ammonia solution-Liquid Ammonium chloride-Solid

Solid ammonium chloride is heated with sodium hydroxide solution ________________________________ is evolved.

The gas ammonia

How is ammonia recognized?

Due to its strong pungent smell.

Dilute hydrochloric acid is heated with iron sulphide ___________________is evolved.

Hydrogen sulphide.

Solid ammonium chloride+ sodium hydroxide solution.

Ammonia gas.

Dilute hydrochloric acid + Iron sulphide-------------------)

Hydrogen sulphide+ Iron chloride.

What is the rotten egg smelling gas ?

Hydrogen sulphide.

Define endothermic reaction.

The reaction which takes place when energy is absorbed.

Define exothermic reaction.

The reaction which takes place when energy is released or evolved..

True or False Chemicals reactions are mostly accompanied by a change in energy.

True

Energy is either ____________ (__________) or ________________.

released evolved absorbed.

Baking soda::Sodium bicarbonate::solid Quick lime::________________:::__________

Calcium oxide::solid

What do you observe when quick lime is added to water?

Heat energy is evolved.

Calcium oxide(____________) +Water-----------------------)

Solid Calcium hydroxide +Heat

What do you observe: When magnesium burns in in air or oxygen?

A white dazzling light is produced.

Magnesium + Oxygen----(heat)-------)

Magnesium oxide(compound)

Coal+ Oxygen----------(heat)-------------)

Carbon dioxide +heat +light.

Calcium carbonate-------(strong heating)----------)

Calcium oxide +carbon dioxide.

Carbon dioxide +water ------- sunlight---------)

Carbohydrates (glucose)+Oxygen

When does transfer of energy take place in a chemical reaction?In the form of?

During the formation of products from the reactants in the from of heat and light and sometimes in the form of sound and electricity too.

What do you observe? Sodium hydroxide solution + dilute hydrochloric acid

It becomes slightly warm.

Sodium hydroxide+ Dilute hydrochloric acid------------------)

Sodium chloride+water+heat

What are the conditions necessary for chemical reactions?

Close contact Solution form Heat Light Electricity and Catalyst

Mostly, energy is either absorbed or released in the form of..... Can it release energy in the form of sound and electricity.

Heat and light. Yes it can.

Explain: Sodium is stored in kerosene oil in laboratories.

Sodium is stored in kerosene oil to prevent its contact with even moisture.

What is he main condition necessary for chemical reaction?Meaning...

Close contact.They should be mixed.

Some substances react with each other only when they are mixed in __________________ .

solution form.

What do you observe when: Solid sodium chloride and silver nitrate are mixed?

Nothing. No change takes place.

Solid Sodium chloride + Solid Lead nitrate.

What do you observe when: Sodium chloride solution + silver nitrate solution.

A white precipitate of silver chloride is formed and a soluble sodium nitrate is formed.

Aqueous solutions of sodium chloride+ Lead nitrate.......

Lead chloride (white insoluble precipitate.)

Brief: Silver nitrate- Silver chloride- Sodium nitrate-

Silver nitrate-Aqueous liquid Silver chloride- White Precipitate Sodium nitrate-Soluble solution.

Iron + Sulphur -------(heat)-------)

Iron sulphide

Carbon dioxide+ water----------(chlorophyll , sunlight)-------------)

Glucose

Water(Acidulated)------(electric current)------------)

Hydrogen +Oxygen.

Potassium Chlorate-----------(manganese dioxide)-------------)

Potassium chloride+ oxygen.

Potassium Chlorate-----------(manganese dioxide)-------------)Potassium chloride+ oxygen. IN this equation does Manganese dioxide undergo any change in its chemical composition?

Define catalyst.

A catalyst is a substance that changes the rate of the chemical reaction, without itself undergoing any chemical change.

Define chemical equation.

When the reactants and products of a chemical reaction are represented symbolically using their symbols and formulae it is called as a chemical equation.

The reactants are written in the _______ hand side and the products in the _________ hand side.

left right

What is put between the reactants and products?

AN arrow sign

Where does the head of the arrow sign always point?

Towards the product.

If 2 or more reactants and products are represented in the equation each is separated by a _____________ sign

plus(+)

What are the 2 ways chemical reactions can written?

Word equation Chemical equation using symbols and formulae

Carbon+ oxygen---------)

Carbon dioxide.

Sodium hydroxide + Sulphuric acid-------------)

Sodium sulphate + water

C+O2 ---------)

CO2

Why is writing a chemical equation better than writing a word equation?

Because it saves time, space and energy.

Zinc oxide+ Carbon--------) Write it in a chemical or symbolic equation.

Zinc + Carbon monoxide ZnO + C-----) Zn + CO

Define balanced equation.

When the number if atoms present on the product side are equal to the number of atoms present in the reactant side.

Hydrogen + Chlorine---------) Write it in chemical or symbolic equation.

Hydrogen Chloride H2 + Cl2-----------) HCl

Define skeletal equation.

When the number of atoms in the reactant is NOT equal to the number of atoms in the product, such an equation is known as an unbalanced or skeletal equation.

True/False All chemical equations must be balanced in order the follow the law of conservation of matter or mass.

True

Can a word equation be balanced?

No.

Does the mass of the substances before and after a chemical reaction change?

No.

When is this possible? The mass of the substances before and after a chemical reaction remains the same.

When the total number of atoms of each kind remain the same before and after a chemical reaction.

How is this supported? The total number of atoms of each kind remain the same before and after a chemical reaction

by the law of conservation of matter.

What does the law of conservation of matter state?

Matter can neither be created nor destroyed. It can only be transformed from one form to another.

Why do we need to balance a chemical reaction?

A chemical equation needs to be balanced so as to make the number of atom in reactant and the number of atoms in the product the same.This is because a chemical equation is just a rearangment of atoms, the atoms can neither be created nor destroyed during a chemical reaction.

Balance the equation: H2 + Cl2 ------------) HCl

H2 + Cl2 ------------) 2HCl

Define a balanced equation.

When the number of atoms of each element in the reactant side is equal to the number of atoms in an element on the product side.