Unit 2

Question 1

Elements, compounds and mixtures that are gasses at room temperature

Answer 1

E: Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine
C: Ammonia (NH3)
Mixtures: Carbon Monoxide, Carbon Dioxide, Nitrogen Monoxide, Nitrogen Dioxide, Sulfur Dioxide, Sulfur Trioxide

Question 2

Combustion/Synthesis Reaction

Answer 2

A combination (or synthesis) reaction is one where a new product is created by combination of two or more reactants.

Example:

Hydrogen + Oxygen → Water
H2 + O2 → H2O

Question 3

Decomposition Reaction

Answer 3

Decomposition reaction is one, where one compound decomposes or breaks into two or more different products.

Example

Here, lead nitrate, is getting decomposed (it breaks down} to form lead oxide, nitrogen dioxide, and oxygen. This is an example of decomposition reaction.

Lead nitrate → Lead monoxide + Nitrogen dioxide + Oxygen

Question 4

Displacement or Replacement Reaction

Answer 4

Example

Zn + H2SO4 → ZnSO4 + H2

In the above reaction, zinc replaces hydrogen from sulfuric acid, to form zinc sulfate. Since only the cation is exchanged here, this is a single displacement reaction.

Question 5

Double Displacement

Answer 5

The anions are exchanged between two compounds, or salts. Such reactions results in different combination of cations and anions, at the end.

AB + XY → AY + XB

Example:

BaCl2 + Na2SO4 → BaSO4 + 2NaCl

Question 6

Combustion Reaction

Answer 6

A reaction where mostly an organic compound burns in the presence of oxygen to yield mostly carbon dioxide, water, and other products, is also a type of combination reaction. Combination of any substance with oxygen results in combustion, leading to the burning of the compounds to its elementary products.

Example

C4H10 + O2 → CO2 + H2O

Butane, an organic compound, burns in the presence of oxygen to give carbon dioxide and water.

Question 7

Precipitation Reaction

Answer 7

A double displacement reaction where the reactants are both aqueous but on reacting an insoluble product is formed.

Example

KI (aq) + Pb(NO3)2 (aq) → PbI (s) + 2KNO3 (aq)

Question 8

Acid + Metal ->

Answer 8

Salt + Hydrogen

Question 9

Acid + Metal oxide ->
Acid + Metal hydroxide ->

Answer 9

Salt + water

Question 10

Acid + Metal carbonate->

Answer 10

Salt + Water + Carbon dioxide