chemistry glossary

Question 1

concentration

Answer 1

amount of substance given in a defined space
another definition could be the amount of solute dissolved in a solvent

calculations: C = n/V
Concentration = moles / volume

Question 2

pressure

Answer 2

the force/area
pressure is defined as the physical force exerted on an object

Question 3

pressure (gas)

Answer 3

Gas pressure is the name given to the force exerted by gas particles COLLIDING with the wall of their container

Question 4

volume (gas)

Answer 4

The volume of gas is defined as the space occupied by the gaseous particles at standard temperature and pressure conditions

Question 5

gas laws (year 11 revision)

Answer 5

laws that relate the pressure, volume, and temperature of a gas

Question 6

what are the five gas laws?

Answer 6

-Boyle’s law
-Gay-Lussac’s law
-Avogadro’s law
-Charles’s Law
-The Combined Gas Law (or ideal gas laws)

Question 7

what does boyle’s law state?

Answer 7

so the boyle’s law describes the relationship between the volume and pressure of gases AT constant temperature

“the volume of a gas is inversely proportional to the pressure of a gas at a constant temperature”

Question 8

boyle’s law equations
hint: pressure and volume

Answer 8

can be written as

V ∝ 1/P or P ∝ 1/V or PV = k1

can be used to determine the current pressure or volume of gas and can be represented also as;

P1V1 = P2V2

Question 9

charles’ law
hint: volume and temperature

Answer 9

in a closed system, charle’s law states that at constant pressure, the volume of a gas is directly proportional to the temperature (especially measured in kelvins)

this particular law describes the relationship between the temperature and volume of the gas

Question 10

charles’ law equations

Answer 10

V ∝ T (volume inversely proportional to temperature)

Where, V = volume of gas, T = temperature of the gas in Kelvin. Another form of this equation can be written as;

V1 / T1 = V2 / T2

Question 11

gay lussc’s law
hint: temperature and pressure

Answer 11

Gay-Lussac law gives the relationship between temperature and pressure at constant volume

at a constant volume, the pressure of the gas is directly proportional to the temperature for a given gas

Question 12

gay lussc’s law equations

Answer 12

P ∝ T or P / T = k1

P1 / T1 = P2 / T2

Where P is the pressure of the gas and T is the temperature of the gas in Kelvin.

Question 13

Avogadro’s law

Answer 13

Avogadro’s law states that if the gas is an ideal gas
(An ideal gas is defined as one for which both the volume of molecules and forces between the molecules are so small that they have no effect on the behavior of the gas),
the same number of molecules exists in the system

“The law also states that if the volume of gases is equal it means that the number of the molecule will be the same as the ideal gas only when it has equal volume”

Question 14

Avogadro’s law equations

Answer 14

V / n = constant

or

V1 / n1 = V2 / n2

Where V is the volume of an ideal gas and n in the above equation represent the number of gas molecules

Question 15

combined gas laws

Answer 15

The combined gas law is also known as a general gas equation is obtained by combining three gas laws which include Charle’s law, Boyle’s Law and Gay-Lussac law

the relationship between pressure, volume and temperature is for a fixed quantity of gas

Question 16

combined gas laws equations

Answer 16

The general equation of combined gas law is given as;

PV / T = k

If we want to compare the same gas in different cases, the law can be represented as;

P1V1 / T1 = P2V2 / T2

Question 17

Ideal Gas Law

Answer 17

the ideal gas law is also an amalgamation of four different gas laws. Here, Avogadro’s law is added and the combined gas law is converted into the ideal gas law

This law relates four different variables which are pressure, volume, no of moles or molecules and temperature

Question 18

Ideal Gas Law equations

Answer 18

Mathematically Ideal gas law is expressed as;

PV=nRT

Where,

V = volume of gas.

T = temperature of the gas.

P = pressure of the gas.

R = universal gas constant.

n denotes the number of moles.

Question 19

what happens to the volume when temperature is increased

Answer 19

the volume increases as the temperature increases

Question 20

moles

Answer 20

the mole is a convenient unit to use because of the great number of atoms, molecules, or others in any substance

Calculations:

n=M/m
moles = molar mass / mass

molar mass can be found in the periodic table***

Question 21

electronegativity

Answer 21

Electronegativity is a measure of an atom’s ability to attract shared electrons to itself

electronegativity generally increases as you move from left to right across a period

decreases as you move down a group

Question 22

ionization energy

Answer 22

the amount of energy required to remove an electron from an isolated atom or molecule

ionisation energy decreases down a group, and increases from left to right across a period

Question 23

electron affinity

Answer 23

the energy change that occurs as an atom gains electrons

Electron affinity increases across the periodic table from left to right due to nuclear charge increases.

It also increases from bottom to top in the periodic table due to atomic size

Question 24

atomic radius

Answer 24

The atomic radius of a chemical element is a measure of the size of its atom

also means distance from the center of the nucleus to the outermost isolated electron (atomic size)

the atomic radius of atoms generally decreases from left to right across a period

The atomic radius of atoms generally increases from top to bottom within a group

Question 25

melting point

Answer 25

The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid

Thus, higher the stronger the bond between the atoms, the higher will be the melting poin

Question 26

isotopes

Answer 26

Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons

e.g hydrogen-1 and hydrogen-2 (deuterium)

Examples of radioactive isotopes include carbon-14, tritium (hydrogen-3), chlorine-36, uranium-235, and uranium-238.

Question 27

diluted

Answer 27

weakened or thinned by or as if by having been mixed with something else (such as water)

Question 28

vigour

Answer 28

characterized by or involving physical strength, effort, or energy

Question 29

covalent bond

Answer 29

Covalent bonding involves the sharing of electrons between two or more atoms

e.g water (H2O), carbon dioxide

Question 30

Ionic bonds

Answer 30

Ionic bonds form when two or more ions come together and are held together by charge differences.

Question 31

standard solutions

Answer 31

Standard solutions are solutions of accurately known concentrations, prepared using standard substance