Miscellaneous

Question 1

What must always be included when writing formulae of IONS responsible for MOLECULAR ION peaks or fragment peaks

Answer 1

• a positive charge
  -if the molecule wasn’t charged it wouldn’t be detected in the mass spectrometer

Question 2

Ideal gas equation and units of each component

Answer 2

pV = nRT

p = pressure in pascals (Pa)
V = volume (m^3)
n= number of moles
R = gas constant (8.31 J mol^-1 K^-1)
T = temperature (Kelvin)

Question 3

What is the danger of metal oxides

Answer 3

They are corrosive

Question 4

Use of bumping granules

Answer 4

Provides a surface for bubbles to form on

Question 5

Factors affecting Rf values

Answer 5

• different adsorption to stationary phase (chromatography paper)

-different solubility in the mobile phase
(Solvent)

Question 6

What is the rate equation for Sn1 reactions

Answer 6

Rate = k [ tertiary halogenoalkane]

• as the slowest (rate-determining step) is the heterolytic fission of the R-X bond forming the carbocation intermediate

Question 7

What is the rate equation for Sn1 reactions

Answer 7

• Rate = k [ tertiary carbocation]

• As slowest (rate-determining) step in Sn1, is homolytic fission of R-X bond to form carbocation intermediate

Question 8

What is the rate equation for Sn1 reactions

Answer 8

• Rate = k [ tertiary halogenoalkane]

• As the slowest (rate-determining) step in Sn1 is homolytic fission of R-X bond to form carbocation intermediate

Question 9

How can you make an reaction E cell reaction that isn’t feasible at standard conditions feasible?

Answer 9

-change the conditions
-so that you decrease or increase the standard electrode potential of one of your species
-so E cell is no longer negative

Question 10

What is the rate equation for Sn2 reactions

Answer 10

• Rate = k [ primary halogenoalkane][nucleophile]

-As the slowest (rate-determining) step in Sn2 is the attack of the nucleophile on the halogenoalkane

Question 11

Why are transition metalaqua ion complexes acidic in solution

Answer 11

-the small positively charged central metal cation polarises an O-H bond

-making it easier for water ligands to release hydrogen ions into solution

-metal aqua ions release protons in solution

Question 12

Weak acid-strong base titration pH @ equivalent point

Answer 12

• pH >7
• @ equivalence point A- from ,weak acid ,HA react with water, releasing OH- ions into solution, making the pH at the equivalence point slightly basic

Question 13

Strong acid-weak base titration pH @ equivalence point

Answer 13

-pH <7
-@ equivalence point salt made is slightly acidic (has a weak acidic), which partially dissociates at the equivalence point

Question 14

What is region formed during the titration of a strong acid and a weak base

Answer 14

-Buffer Region
-When [HA] = [A-] , acting as reservoirs, neutralising added base

Question 15

Why is standard enthalpy of Neutralisation for a weak acid less eco thermos than that or a strong acid

Answer 15

• weak acids do not fully ionise
  -therefore more energy has to be put in /used to fully ionisie the acid

Question 16

What is a reagent

Answer 16

A substance or compound added to a system to cause a chemical reaction or test if one occurs

Question 17

What allows for electrons to be promoted within quantum shells e.g sulfur can promote electrons from the 3s and 3p subshell to the 3d subshell

Answer 17

• all of these sub shells are in the same quantum energy level (n=3)

-therefore the difference in energy between the sushells isn’t HUGE, so not too much energy needs to be put in to promote the electrons

(As you move lower down in the periodic table octet expansion becomes rarer as gaps within subshells get larger as you move down quantum shells)

Question 18

What is a the pro to expanding an octet for an atom, despite it taking Energy to promote the electrons

Answer 18

• they can form more covalent bonds
  -covalent bond formation is exothermic, therefore the more bonds you form, the form energy you release
  -so the atom is more stable