Chapter 2, Problem 65E

Distinguish precisely and in scientific terms the differences among items in the following groups.

a) Macroscopic matter, microscopic matter, particulate matter

b) Physical change, physical property, chemical change, chemical property

c) Gases, liquids, solids

d) Element, compound

e) Atom, molecule

f) Pure substance, mixture

g) Homogeneous matter, heterogeneous matter

h) Reactant, product

i) Exothermic change, endothermic change

j) Potential energy, Kinetic energy

Interpretation Introduction

(a)

Interpretation:

The differences between macroscopic matter, microscopic matter, and particulate matter have to be stated.

Concept introduction:

Matter can be classified on the basis of the size of the matter. They can be classified into macroscopic, microscopic and particulate matters.

Answer to Problem 65E

Macroscopic matters are those matters which can be seen by naked eye.

Microscopic matters are those which cannot be seen by naked eyes.

Particulate matters are those which are extremely small and cannot be seen with very high power optical microscope.

Explanation of Solution

Macroscopic matters are those matters which can be seen by naked eye. They are large in size. The size varies from $1\text{m}$ to $1\text{mm}$. Mountains, rocks, tiny grains of sand are macroscopic matter.

Microscopic matters are those which cannot be seen by naked eyes. They are too small that some eye aids like microscope are needed to see them. The size ranges from $1\text{mm}$ to $100\text{nm}$. Plant cells, animal cells are microscopic matter.

Particulate matters are those which are extremely small and cannot be seen with very high power optical microscope. The size ranges from $1\text{nm}$ to $1\text{pm}$. Atoms, carbon dioxide molecule are particulate matter.

Conclusion

The differences between macroscopic matter, microscopic matter, and particulate matter are stated above.

Interpretation Introduction

(b)

Interpretation:

The differences between physical change, physical property, chemical change and chemical property are to be stated.

Concept introduction:

Physical change and the physical property are those which are appeared on changing the state and appearance of the substance. Chemical change and properties are observed when a substance is converted into a new substance by losing its chemical identity.

Answer to Problem 65E

Physical change is the change in the appearance and the state of the substance. Physical properties are those which can be observed without changing the chemical identity of the substance.

Chemical change is the change which brings a change in the appearance and state of the substance. Chemical property of a substance is a group of properties of all the possible chemical changes that can occur in a substance.

Explanation of Solution

Physical change is the change in the appearance and the state of the substance without bringing any alteration in their chemical identity like changing of ice into liquid.

Physical properties are those properties which can be observed without changing the chemical identity of the substance. Boiling point, melting point of a substance are examples of physical change.

Chemical change is the change when there is a change in the chemical identity of the substance and a new substance is formed. The new substance formed has no similar chemical property of the former substance. For example, conversion of an alcohol into carboxylic acid is a chemical change.

Chemical property of a substance is a group of properties of all the possible chemical changes that can occur in a substance. For example, an alcohol can be converted into a ketone, an aldehyde, and a carboxylic acid.

Conclusion

The differences between physical change, physical property, chemical change and chemical property are stated above.

Interpretation Introduction

(c)

Interpretation:

The differences between gases, liquids and solids are to be stated.

Concept introduction:

Gases, liquids and solids are the states of the matter. They differ on the basis of arrangement of molecules in them. Each substance is always present in one of the states.

Answer to Problem 65E

Gases are those substances in which the molecules are very loosely held.

Liquids are those substances in which the molecules are loosely packed.

Solids are those substances in which molecules are tightly packed.

Explanation of Solution

Gases are those substances in which the molecules are very loosely packed. They can spread in any direction. They do not have any specific shape. For example, a room filled with the fragrance of a perfume.

Liquids are those substances in which the molecules are loosely packed. They flow in one direction only. They do not have any specific shape and takes the shape of the container. For example, same amount of water in a glass, bowl.

Solids are those substances in which the molecules are tightly packed. They have a specific shape. For example, table, chair.

Conclusion

The differences between gases, liquids and solids are stated above.

Interpretation Introduction

(d)

Interpretation:

The differences between elements and compounds are to be stated.

Concept introduction:

An element and a compound are differentiated on the composition of atoms. An element is composed of single types of atoms. A compound is composed of two or more types of atoms.

Answer to Problem 65E

An element is composed of single type of atoms which have unique physical and chemical properties.

A compound is made up of atoms of different elements.

Explanation of Solution

An element is a pure substance which is composed of single type of atoms which have unique physical and chemical properties. An element cannot be dissociated further. For example, hydrogen, lithium is composed of hydrogen atoms and lithium atoms respectively.

A compound is a composed of two or more elements. It has different physical and chemical properties than the elements present in it. A compound can be dissociated into two or more pure substances. For example, water is made up of hydrogen and oxygen.

Conclusion

The differences between element and compound are stated above.

Interpretation Introduction

(e)

Interpretation:

The differences between an atom and a molecule are to be stated.

Concept introduction:

Atom is the smallest unit of a matter. Molecule is composed of two or more atoms.

Answer to Problem 65E

An atom is the smallest unit of a matter. A molecule is composed of two or more atoms of an element.

Explanation of Solution

An atom is the smallest unit of a matter. For example, hydrogen is made up of hydrogen atoms.

A molecule is composed of two or more atoms of an element. For example, oxygen molecule is composed of two oxygen atoms.

Conclusion

The differences between an atom and a molecule are stated above.

Interpretation Introduction

(f)

Interpretation:

The differences between pure substances and mixture are to be stated.

Concept introduction:

A pure substance and a mixture of substances are differentiated on the basis of the number of substances present in them. A mixture is made up of two or more pure substances, that is, two or more types of elements. It has properties of the elements present in it.

Answer to Problem 65E

A pure substance is made up of only one type of substance only.

A mixture is made up of two or more pure substances.

Explanation of Solution

A pure substance is made up single type of matter only. It has its own specific physical and chemical properties. The properties of a pure substance do not change on changing the quantity of an element. For example, lithium element is made up of only lithium atoms.

A mixture is made up of two or more pure substances, that is, two or more types of elements. It has properties of the elements present in it. As the quantity of elements are changed their properties also change. For example, water is a mixture of hydrogen and oxygen elements.

Conclusion

The differences between pure substances and a mixture are stated above.

Interpretation Introduction

(g)

Interpretation:

The differences between homogeneous and heterogeneous matter are to be stated.

Concept introduction:

A homogeneous mixture and heterogeneous mixture can be differentiated on the basis of their composition and appearance.

Answer to Problem 65E

A homogeneous mixture is a mixture which has similar composition and appearance throughout.

A heterogeneous mixture is a mixture which does not have similar composition and appearance throughout.

Explanation of Solution

A homogeneous mixture is a mixture which has similar composition and appearance throughout. Prefix “homo” in homogeneous means “same”. It can be separated through chemical methods. For example, water and alcohol have similar composition throughout.

A heterogeneous mixture is a mixture which does not have similar composition and appearance throughout. Prefix “hetero” in heterogeneous means “different”. It can be separated through physical methods like distillation. For example, mixture of water and oil can be seen in two different layers.

Conclusion

The differences between homogeneous and heterogeneous matter are stated above.

Interpretation Introduction

(h)

Interpretation:

The differences between reactants and products are to be stated.

Concept introduction:

Reactants and products are the chemical species which are present before and after the chemical change takes place respectively.

Answer to Problem 65E

Reactants are the substances which were originally present before a chemical change took place. Products are substances which are present after chemical change.

Explanation of Solution

Reactants are the substances which were originally present before a chemical change took place. They are written on the left hand side of the chemical equation.

Products are substances which are present after chemical change. They are written on the right hand side of the chemical equation.

For example, in a chemical reaction, $\text{A}+\text{B}\to \text{C}+\text{D}$, $\text{A}$ and $\text{B}$ are reactants; and $\text{C}$ and $\text{D}$ are products.

Conclusion

The differences between reactants and products are stated above.

Interpretation Introduction

(i)

Interpretation:

The differences between exothermic change and endothermic change are to be stated.

Concept introduction:

Exothermic and endothermic are classified on the basis of heat change in a chemical reaction. An endothermic change is a change when heat is required to bring a chemical change. Energy is removed from the surrounding.

Answer to Problem 65E

When heat is evolved in a chemical reaction, exothermic change takes place.

When heat is required in a chemical reaction, an endothermic change occurs.

Explanation of Solution

When a chemical change takes place with the evolution of heat, an exothermic change takes place. Energy is transferred to the surrounding. Exothermic energy always has a positive numerical value.

An endothermic change is a change when heat is required to bring a chemical change. Energy is removed from the surrounding. Endothermic energy always has a negative numerical value.

Conclusion

The differences between exothermic and endothermic change are stated above.

Interpretation Introduction

(j)

Interpretation:

The differences between potential energy and kinetic energy are to be stated.

Concept introduction:

Kinetic energy is related to the movement of the objects. Potential energy is based on the arrangement of charges in an object. Potential energy is related to the arrangement of positive and negative charges in a substance.

Answer to Problem 65E

Kinetic energy is related to the movement of the objects. Potential energy is based on the arrangement of charges in an object.

Explanation of Solution

Kinetic energy is related to the motion of objects. When a car moves, it is possessing kinetic energy. It depends upon the velocity, higher the velocity, higher will be the kinetic energy.

Potential energy is related to the arrangement of positive and negative charges in a substance. Potential energy increases when similar charges are moved closer to each other and when unlike charges are separated from each other.

Conclusion

The differences between potential energy and kinetic energy are stated above.