Amount of Substance

Question 1

What does the avogadros constant represent

Answer 1

The number of atoms per mole of the carbon 12 isotope

Question 2

Formula for Mass Mr.Moles

Answer 2

Mass= Mr x Moles

Question 3

What is avogradros law

Answer 3

Under the same temp and pressure one mole of any gas would occupy the same volume

Question 4

How much volume does a gas occupy at room temp and pressure

Answer 4

24dm^3 or 24,000 cm^3

Question 5

Define molar gas volume

Answer 5

The volume per mole of gas molecules

Question 6

Why do different particles occupy the same volume

Answer 6

The gas particles are very spread out hence individual differences has no effect

Question 7

How do you calculate moles when gas volume is given?

Answer 7

Moles= volume (dm3) / 24
or
Moles= volume (cm3) / 24000

Question 8

What are the ideal way in which gases behave (5)

Answer 8

*They are in continuous motion
*No intermolecular forces are experinced
*Exert pressure when they collide with each other or the container
*No kinetic energy is lost in the collisions
*When temperature increases the kinetic energy also increases

Question 9

What is the ideal gas equation

Answer 9

PV=NRT
Pascals x volume (m^3)= Number of moles (mol) x gas constant (8.314) x Temperature (kelvin)

Question 10

How much is 1 atmospheric pressure equal to in pa and kpa

Answer 10

101325 pascals
Or
101KPA

Question 11

What is 50 degrees celcius into Kelvin and what is 40 kelvin into celcius

Answer 11

50+273=323
40-273=-233

Question 12

What does concentration of a solution mean

Answer 12

It is the amount of solute dissolved in 1 dm^3 of solvent

Question 13

How do you calculate moles when conc and vol are given

Answer 13

moles = conc x vol
Conc=mol/dm3

Question 14

What is a standard solution

Answer 14

A solution of known conc

Question 15

What does the term concentration mean

Answer 15

large amount of solute per dm^3

Question 16

What does the term dilute mean

Answer 16

small amount of solute per dm^3

Question 17

What is a species in a chemical reaction

Answer 17

any particle that takes part in the reaction

Question 18

What are the 4 common state symbols

Answer 18

Gas(g)
Liquid(l)
Solid(s)
Aqueous (aq)

Question 19

What does percentage yield mean

Answer 19

The efficient of which reactants are converted into products

Question 20

What are the reasons for not obtaining 100% percebtage yie;d

Answer 20

*Reaction may be at equilibrium
*The reactants may be impure
*Side reactions could happen
*Reactants or products may be left behind while transferring
*Loss of products during separation and purifciation

Question 21

How is pervenatge yield calculated

Answer 21

Percentage yield=Actual amount of product/ theortical amount of product x100

Question 22

What does atom economy tell you

Answer 22

The proportion of desired products compared with all the products formed with the reaction

Question 23

How is atom economy calculated

Answer 23

Atom economy= Molecular mass of desired product/sum of the molecular masses of all products x 100

Question 24

Define solution

Answer 24

A solution consists of a solvent with a solute dissolved in it

Question 25

How many decimetres are there in 1000cm^3

Answer 25

1dm^3

Question 26

Define Ar

Answer 26

Average mass of one atom of an element compared to 1/12 of a carbon 12

Question 27

Define empirical formula

Answer 27

The simplest whole number ratio of atoms of each element in a compound