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Flashcards in Gaps Deck (34):
1

Which statements are correct for the reaction of ethene with bromine the absence of ultraviolet light?

I. It is an addition reaction

II. The organic product is colorless

III. The organic product is saturated

II and III

2

State the equation for the reaction between methane and bromine to form bromomethane.

CH4 + Br2 --> CH3Br + HBr

3

Bromine can be produced by electrolysis of molten sodium bromide. Deduce the half-equation for the reaction at each electrode.

  • Positive electrode (anode): 2Br- --> Br2 +2e-
  • Negative electrode (cathode): Na+ + e- --> Na

4

State one difference in the physical properties of the isotopes between 63Cu and 65Cu and explain why their chemical properties are the same.

  • 63Cu diffuses at a greater rate than 65Cu
  • have the same number of protons and electrons

5

C5H12​ exists as three isomers. Identify the structure of the isomer with the lowest boiling point and explain your choice.

  • 2,2-dimethylpropane
  • weakest London dispersion forces because has smallest surface area

6

Ethanol is a primary alcohol that can be oxidised by acidified potassium dichromate (VI). Distinguish between the reaction conditions needed to produce ethanal and ethanoic acid.

  • Ethanal: distill off product as it forms
  • Ethanoic acid: use excess oxidising agent 

7

Deduce the half-equation for the oxidation of ethanol to ethanal.

CH3CH2OH --> CH3CHO + 2H+ + 2e-

8

If a reaction has an exothermic forward reaction, what would happen to the equilibrium constant for the reaction if the temperature were increased?

decrease

9

coordinate (dative) bonds

  • the electrons in the shared pair originate from the same atom 
  • e.g. sulfur dioxide and sulfur trioxide has dative bond between S and O

10

Which forces are present between molecules of carbon dioxide in the solid state?

temporary dipole-induced dipole interactions

11

What is the equation for the bond enthalpy of the H-I bond?

HI (g) --> H (g) + I (g)

12

State an equation for the formation of ethanol from ethene and the necessary reaction conditions.

  • CH2CH2 + H2O --> CH3CH2OH
  • concentrated sulfuric acid

13

Bronsted-Lowry vs. Lewish acids and bases

  • Bronsted-Lowry: acid is a proton donor, base is a proton acceptor
  • Lewis: acid is an electron acceptor, base is an electron donor

 

14

Outline how the Mg+ ion is formed in the mass spectrometer. Describe how Mg+ is accelerated in the mass spectrometer.

  • collision of Mg atom with high energy electrons
  • ion passes through oppositely charged plates

15

Why in the Haber process is 

  1. a temperature lower than 500C not used?
  2. a pressure higher than 200atm not used?

  • slower rate, uneconomical
  • high cost for maintaining plant

16

Outline an experiment and its results which could be used to distinguish between a strong base and a weak base.

  • solutions of equal concentrations of acid and base
  • measure pH
  • strong base has higher pH

17

Identify the acid-base character of the oxides of each of the elements from sodium to chlorine in period 3.

Na, Mg oxides - basic

Al oxide - amphoteric

Si-Cl oxides - acidic

18

Outline two reasons why the polymerisation of alkenes is of economic importance.

  • polymers not naturally available
  • wide range of uses

19

allotrope

when an element can exist in different crystalline forms (e.g. carbon)

20

Boiling points for organic molecules 

  • As the carbon chain in a homologous series increases the London dispersion forces of attraction increase so boiling point increases
  • when branching occurs the molecules become more spherical in shape so the surface area decreases and the boiling point decreases

21

what structural feature must a molecule possess in order that it may undergo addition polymerisation?

carbon-carbon double bond

22

IHD equation

(2C + 2 + N - H - halogens) / 2

23

primary, secondary, tertiary halogenoalkanes

  • primary halogenoalkane: carbon holding halogen is attached to one other thing
  • secondary halogenoalkane: carbon holding halogen is attached to two other things
  • tertiary halogenoalkane: carbon holding halogen is attached to three other things

24

25

what is the pH of acid rain?

less than 5.6

26

why does the soil become salty in areas where soil is constantly irrigated?

  • irrigation waters contain dissolved salts
  • salts left behind when water evaporates

27

describe two ways in soil organic matter contributes to preventing soil degradation

  • provides sources of nutrients
  • improves structural stability

28

what is Kc for the reverse reaction?

Kc-1

29

How are the mass and abundance of an isotope determined in mass spectrometry? 

  • magnetic field required to deflect isotope onto detector depends on mass of isotope
  • signal from detector depends on abundance of isotope

30

How does the atomic radii of isotopes vary?

  • same atomic radii
  • isotopes only differ by number of neutrons whereas atomic radius is determined by electron shells and number of protons

31

is dissolving endothermic or exothermic?

endothermic

32

greater the specific heat capacity, ... increase in temperature for a given energy input

greater

33

evaporation vs. boiling

  • evaporation occurs at all temperatures, boiling at bp only
  • evaporation occurs at surface, boiling throughout

34

free radical mechanism diagram