Identify the substances and their uses, and describe the chemical reactions and properties for questions 13-15.

13. a) M - Graphite N - Amorphous carbon

b)
One use of amorphous carbon (N) is as fuel (e.g., charcoal) or as an adsorbent (e.g., activated carbon).

14. a) Solid H, when heated, decomposes into Carbon (IV) oxide ($\text{CO}_2$) and Solid J. Solid J reacts with water to form calcium hydroxide ($\text{Ca(OH)}_2$). This indicates that Solid J is calcium oxide ($\text{CaO}$), and Solid H is calcium carbonate ($\text{CaCO}_3$).

$$\text{CaCO}_3(s) \xrightarrow{\text{Heat}} \text{CaO}(s) + \text{CO}_2(g)$$ $$\text{CaO}(s) + \text{H}_2\text{O}(l) \rightarrow \text{Ca(OH)}_2(aq)$$

Solid J: Calcium oxide ($\text{CaO}$) Solid H: Calcium carbonate ($\text{CaCO}_3$)

b)
One commercial use of solid H ($\text{CaCO}_3$) is in the manufacture of cement.

15. When ammonium nitrate is gently heated, it decomposes to form dinitrogen monoxide (nitrous oxide) gas and water vapor.

$$\text{NH}_4\text{NO}_3(s) \xrightarrow{\text{Heat}} \text{N}_2\text{O}(g) + 2\text{H}_2\text{O}(g)$$

Gas G is dinitrogen monoxide ($\text{N}_2\text{O}$).

Physical properties:

• It is a colorless gas.
• It has a sweet smell.
• It is denser than air.
• It is slightly soluble in water.

Chemical test:

• Insert a glowing splint into a test tube containing gas G. The splint will relight, indicating the presence of dinitrogen monoxide.