Deck 25: Hydrogen

Question 1

The presence of hydrogen was first detected when a flammable gas was released after dissolution of iron filings in hydrochloric acid.

Answer 1

True

Question 2

Despite often being placed at the top of the group 1 elements, hydrogen does not fit this classification well despite the ns¹ ground state configuration.

Answer 2

True

Question 3

Which of the following statements apply to hydrogen? Please select all that apply.

A) Elemental hydrogen exists as a dimer with the lowest density of all the gases.
B) H₂ is generally unreactive unless in the presence of a catalyst.
C) Occurs naturally on Earth.
D) While the bond enthalpy of H₂ is high, the intermolecular forces between hydrogen molecules are weak.

Answer 3

A, B, D

Question 4

Hydrogen gas has the lowest ______ of any gas

Question 5

Producing hydrogen for use in fuel cells is attracting interest in the search for alternatives to fossil fuels, due to concerns about global warming. Using hydrogen produced via the steam reforming process in fuel cells would not entirely alleviate the problem.

Question 6

If hydrogen forms a compound with an element that is more electropositive than itself it is known as protic.

Question 7

The Periodic Table of the elements forms four different types of hydride. Match the type of hydride with the appropriate compound.
-AsH₃

A) Electron-rich hydride
B) Electron-deficient hydride
C) Ionic hydride
D) Electron-precise hydride

Question 8

The Periodic Table of the elements forms four different types of hydride. Match the type of hydride with the appropriate compound.
-B₂H₆

A) Electron-rich hydride
B) Electron-deficient hydride
C) Ionic hydride
D) Electron-precise hydride

Question 9

The Periodic Table of the elements forms four different types of hydride. Match the type of hydride with the appropriate compound.
-KH

A) Electron-rich hydride
B) Electron-deficient hydride
C) Ionic hydride
D) Electron-precise hydride

Question 10

The Periodic Table of the elements forms four different types of hydride. Match the type of hydride with the appropriate compound.
-CH₄

A) Electron-rich hydride
B) Electron-deficient hydride
C) Ionic hydride
D) Electron-precise hydride

Question 11

LiH and MgH₂ show similarities in their bonding, this is an illustration of the ____________ relationship.

Question 12

Cerium hydride has a structure based on the fluorite structure where cooperative reorganisation of the anion sublattice allows extra hydrogen to be incorporated inside the structure such that x = 0.25. On strong heating all the hydrogen can be liberated from the structure. What percentage of its own mass in hydrogen can Ce absorb within the structure when x =0.25. RAM (g mol^-1) of Ce = 140.12, H = 1.01.

A) 1.58%
B) 1.62%
C) 2.18%
D) 2.21%

Question 13

Diborane reacts with compounds of the formula NR₃ where R = H and Me to form an adduct. The adduct where R = Me is more stable.

Question 14

BH₄^- is using in organic chemistry as a _______ agent where it is a source of H^- ions

Question 15

As Group 14 is descended, the hydrides become less stable.

Question 16

In contrast to NH₃, the rest of the Group 15, MH₃ compounds, show relatively poor Lewis base character. Why is this?

A) There are fewer valence electrons available.
B) For the rest of the Group 15 hydrides, the orbitals are not properly hybridized and the lone pair is not readily available for bonding.
C) The centres are sterically hindered due to short bond lengths and it is difficult to coordinate to the lone pair.
D) The hydrides are ionic.

Question 17

Phosphine cannot be synthesized directly from phosphorus and hydrogen.

Question 18

Liquid ammonia can undergo self-ionisation to form NH₂^- and NH₄⁺ .

Question 19

Which of these statements apply to H₂S? Please select all that apply.

A) Heat of formation is endothermic.
B) Humans recognise the characterise smell of hydrogen sulfide at concentrations less than 1 ppm.
C) At lethal concentrations, the human olfactory nerve can be paralysed, making H₂S particularly dangerous.
D) H₂S is a gas at room temperature.

Question 20

H₂O₂ is an hydride of oxygen, what is the oxidation state of the oxygen?.

A) -2
B) 0
C) -1
D) +1

Question 21

Heating H₂O₂ in air causes a _____________ reaction where the oxygen is reduced and oxidised simultaneously to O₂ (oxidation state 0) and H₂O (oxidation state -2)

Question 22

Match the enthalpy of formation with the appropriate Group 17 hydrogen halide
-+26.5 kJ mol^-1

A) HI
B) HCl
C) HF
D) HBr

Question 23

Match the enthalpy of formation with the appropriate Group 17 hydrogen halide
--92.3 kJ mol^-1

A) HI
B) HCl
C) HF
D) HBr

Question 24

Match the enthalpy of formation with the appropriate Group 17 hydrogen halide
--271.1 kJ mol^-1

A) HI
B) HCl
C) HF
D) HBr

Question 25

Match the enthalpy of formation with the appropriate Group 17 hydrogen halide
--36.4 kJ mol^-1

A) HI
B) HCl
C) HF
D) HBr

Question 26

The acidity of the hydrogen halides decrease as the bonds become less polar.

Question 27

Which of the following species could be hydrogen bond acceptors? Please select all that apply

A) N
B) Cl
C) Fe
D) O

Question 28

Which of the following points suggests that the first hydride in Groups 14-17 exhibit hydrogen bonding. Please select all that apply.

A) There is a steady increase in the boiling point of the hydrides from the second row onwards but the boiling point of the hydride for the first element in any group is anomalously high.
B) There is a steady increase in the melting point of the hydrides from the second row onwards but the boiling point of the hydride for the first element in any group is anomalously high.
C) There is a steady decrease in the boiling point of the hydrides from the second row onwards but the boiling point of the hydride for the first element in any group is anomalously high.
D) There is a steady decrease in the melting point of the hydrides from the second row onwards but the boiling point of the hydride for the first element in any group is anomalously high.

Question 29

Which of the following statements about the solid structure of ice are true. Please select all that apply.

A) Once the hydrogen-bonded framework has broken down the density falls steadily as the temperature rises.
B) The solid structure of ice is less dense than water.
C) As the solid ice network starts to break down and molecules tumble into the holes in the framework, the density is higher at 4 °C than either the solid ice network at 0 °C or liquid water at 30 °C.
D) The solid structure of ice is more dense than water.

Question 30

The C-H bond of an alkane has an IR absorption for C-H at 2930 cm^-1, the analogous C-D absorption would be observed at 2344 cm^-1.