2.1.3 Amount Of Substance

Question 1

How do you find moles from a mass

Answer 1

moles= mass/mr

Question 2

hoe do you find moles from volume and concentration

Answer 2

moles=volumeXconcentration n=vc

Question 3

how do you find moles from a gas

Answer 3

moles (gas) = vol (dm3)/ 24 OR vol (cm3)/ 24000

Question 4

what is avogadro’s Law?

Answer 4

under the same temperature or pressure, any mole of a gas will occupy the same volume

Question 5

how much volumr does one mole of a gas occupy at standard temp/pressure

Answer 5

24 dm3 or 24,000 cm3

Question 6

what is the ideal gas equation?

Answer 6

pV=nRT

p= pressure (Pa)
V= volume (M^3)
n= moles
R= gas constant (8.314)
T= temperature (k)

Question 7

How many Pascal is 1atm

Answer 7

1atm = 101,000 PA

Question 8

how do you turn Celsius into Kelvin?

Answer 8

Add 273

Question 9

what is a standard solution?

Answer 9

a solution of known concentration

Question 10

how do you prepare a standard solution?

Answer 10

1) weight the solute using the weigh by difference method
2) in a beaker, completely dissolve the solute in the solvent
3) pour the solution into a volumetric flask
4) rinse the beaker with distilled water to get any residual solution into the flask
5) Add distilled water (solvent) until the graduation line
6) mix thoroughly to ensure its mixed

Question 11

give reasons why you may not have a 100% percentage yield

Answer 11

• The reaction is at equilibrium
• impure reactants
• other side reactions may be happening
• reactants/products left behind in transferral
• loss of products doing purification/separation
• kara is awesome :D NO SHES NOT

Question 12

how is percentage yield calculated

Answer 12

percentage yield = actual yeild (mol)/theoretical yeild X 100

Question 13

what does atom economy mean?

Answer 13

the amount of desired product compared to all products formed

Question 14

how do you calculate atom economy

Answer 14

atom economy = (Mr/sum of mr of all products) X100

Question 15

does 100% yield mean 100% atom economy?

Answer 15

No because there may be multiple products in the yield so there may not be 100% o the desired product

Question 16

state what is meant by the term empirical formula

Answer 16

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

Question 17

what is a subshell?

Answer 17

The independent energy levels housing electrons in a shell of electrons
e.g. 3s2 3p6 3d10 are all subshells

Question 18

what are orbitals?

Answer 18

pairs of electrons in a shell

Question 19

what is meant by the term isotope

Answer 19

an atom of an element with the same number of protons but a different number of neutrons

Question 20

why do some different isotopes of the same element have the same chemical properties?

Answer 20

Because they have the same electron configuration

Question 21

what is meant by the term relative atomic mass? (Ar)

Answer 21

The weighted mean mass of an atom compared with 1/12 of the mass of a single carbon 12 atom

Question 22

what is meant by the term relative isotopic mass?

Answer 22

the mass of an isotope relative to 1/12 th of the mass of an atom of carbon 12

Question 23

how do you calculate relative atomic mass (Ar) from % abundances?

Answer 23

Ar = (mass x Abundance) + (mass x Abundance) / total abundance

you can use this to find out the Ar of an isotope simply by rearranging

Question 24

What is meant by the term relative formula Mass? (Mr)

Answer 24

The Mr of a compound is the sum of all the atomic masses of each atom in the formula

Question 25

what is the equation for finding the abundances of isotopes?

Answer 25

https://docs.google.com/document/d/17_ChjSZF0Sc_dkYUKqLJrHYHaeOCpJga1vV2fxhPb5M/edit?usp=sharing

%abundance = (pull / difference) x100

Question 26

what is Avogadro’s number?

Answer 26

6.02x10^23

Question 27

what is the value for the specific heat capacity of water?

Answer 27

4.18

Question 28

what is the value for the gas constant?

Answer 28

8.31