Question

UCCul Reactions What is the difference between a physical change and a chemical change? List Types of visible evidence of a chemical change? (6 or more) What is a chemical reaction? What is a chemical equation? Reactants are? Products are? What is a balanced equation? Coefficients vs Subscripts vs Superscripts Types of Reactions: Combination: Decomposition: Single Replacement Double Replacement Combustion Oxide reaction Oxidation-Reduction Oxidation Reduction

Answer 1

Q)

A)

1.

The diffrence between physical and chemical change is an composition.In chemical change the change in the composition of substance where as in physical there will be a change in smell,apperance without any change in composition. Though we call physical reaction but there is no reaction.

2.

There are many things that indicate or shows that the chemical change take place but this doesnt give an conclusion.

A)Change of odour.

B)Change of colour.

C)Change in temperature or energy.

D)Change of composition.

E)Formation of precipitate.

3.

Chemical changes occurs only when any substance will combines with other substance which form new substance.And this we are calling as an chemical synthesis

And decomposition in diffrent substance is called as chemical reaction.All reactions are not reversible in this.Some reaction produces the heat and known as exothermic reaction.And the reaction that require heat to perform reaction is known as endothermic reaction.

When ever chemical reaction take place there will be re arrangement of atoms take place due to which chnage in energy take place and hence the formation of product take place .

For example take sodium and water that form the product known as sodium hydrooxide and hydrogen.

4.

  CHEMICAL EQUATION:

It is an symolic representation of an reaction that is in chemical reaction.It shows in the form of symbols and formulas.In this reactant will be at left hand side and product are at right hand side

In 1615 jean beguin is the one who discoverd this chemical equation.

REACTANTS:

It is an substance that takes part in an reaction and undergoes into changes.And when they undergo into an chemical reaction it form product.

For example methan and oxygen are reactant where as carbon dioxide and water is product.

PRODUCTS:

They are species , substance that are formed in chemical reaction .During the reaction reactants transformed into product due to change in its energy.

For example photosynthesis in this reactants are carbondioxide , water and sunlight and products are glucose and oxygen.

5.

BALANCED EQUATION:

It is an equation in which the atom.no of an element and the total charge of reactant and product are same.Hence we called it as balanced reaction.

  COEFFICIENT vs SUBSCRIPTS vs SUPERSCRIPTS:

  Coefficient:

A no that is use to multiply a variable . For example 6Z here the 6 time Z where Z is an variable and 6 is coefficient.The variable that has no number will have 1 coefficient.

Subscripts:

It means or shows how many atoms or molecules are present.Usually write as an formula for example H₂O .Here 2 reprsent thw presence of hydrogen that is 2 where as oxygen js 1.

  Superscripts:

It shows the charge of ion of particular atom or molecule.Or can say that no of electron in an subshell.

6.

COMBINATION:

It is define as one or more substance when combine to form an single substance under a suitable type of an condition known as combination.It is also calles as synthesis as there is an formation of an new substance.

DECOMPOSITION:

It means break down of single or one substance into one or more fragment.This is an opposite of combination or synthesis. Because here more than one product form from single reactant.

SINGLE REPLACEMENT:

It means where the one substance is replace with another in an compound.For example A+B-C $\rightarrow$ A+C-B.

DOUBLE REPLACEMENT:

It means exchange of bonds between two non reacting substance and that forms an product that contain similar bonding.

COMBUSTION:

  It is also known as burning. Which means high temperature exothermic reaction.For example comustion in fir leads to form flame.

OXIDE REACTION:

The reaction that contain one oxygens atom and one another element known as oxide reaction.

For example water (hydrogen oxide) the formula of this is H₂O and commonly used in solvent and are required by carbon based lifes.

OXIDATION-REDUCTION:

Any chemical reaction in which oxidation no of atom ion get changes by losing or gaining an electron.

OXIDATION:

It means loss of electron during an reaction from or by molecule ,atom , and ion.It occurs state of any molecule,atom and ion increases.

REDUCTION:

  Opposite to oxidation the reduction comes.It involves gaining of electron from molecule , atom and ion .It accepts electron.