Question

e. some compounds can be synthesized by combination of the elements

1. fe(s) + o2(g) → fe2o3(s)
2. cu(s) + cl2(g) → cucl(s)
3. na + o → na2o2(s)
4. h + o → h2o(aq)
5. n + h → nh3(g)
6. p4(s) + h → ph3(g)

ii. decomposition reactions some compounds can be decomposed to other compounds and/or elements
22.hgo(s) heat→ hg(ℓ) + o2(g)
23.pbo2(s) heat→ pbo(s) + o2(g)
24.kclo3(s) heat→ kcl(s) + o2(g)
25.naclo3(s) heat→ nacl + o
26.h2o2(aq) catalyst→ h2o(ℓ) + o2(g)
27.h2o(ℓ) d.c.→ h + o2
28.nano3(s) heat→ nano2(s) + o2
29.caco3(s) heat→ cao(s) + co2(g)
limestone quicklime
iii. single replacement reactions
a. reactive metals react with acid to produce hydrogen gas.

1. zn(s) + hcl(aq) → zncl2(aq) + h2(g)
2. al(s) + h2so4(aq) → al2(so4)3(aq) + h2(g)
3. pb(s) + h3po4(aq) → pb3(po4)2(s) + h2(g)
4. mg(s) + hcl(aq) → mgcl + h2(g)
5. ca(s) + h2so4(aq) → caso4 + h2(g)

Explanation:

Step1: Balance combination reactions

1. \(2Na(s)+O_2(g)

ightarrow Na_2O_2(s)\)

1. \(2H_2(g)+O_2(g)

ightarrow 2H_2O(aq)\)

1. \(N_2(g)+3H_2(g)

ightarrow 2NH_3(g)\)

1. \(P_4(s)+6H_2(g)

ightarrow 4PH_3(g)\)

Step2: Balance decomposition reactions

1. \(2NaClO_3(s)\xrightarrow{heat}2NaCl(s)+3O_2(g)\)
2. \(2H_2O(l)\xrightarrow{D.C.}2H_2(g)+O_2(g)\)

Step3: Balance single - replacement reactions

1. \(2Al(s)+3H_2SO_4(aq)

ightarrow Al_2(SO_4)_3(aq)+3H_2(g)\)

1. \(3Pb(s)+2H_3PO_4(aq)

ightarrow Pb_3(PO_4)_2(s)+3H_2(g)\)

1. \(Mg(s)+2HCl(aq)

ightarrow MgCl_2(aq)+H_2(g)\)

1. \(Ca(s)+H_2SO_4(aq)

ightarrow CaSO_4(aq)+H_2(g)\)

Answer:

1. \(2Na(s)+O_2(g)

ightarrow Na_2O_2(s)\)

1. \(2H_2(g)+O_2(g)

ightarrow 2H_2O(aq)\)

1. \(N_2(g)+3H_2(g)

ightarrow 2NH_3(g)\)

1. \(P_4(s)+6H_2(g)

ightarrow 4PH_3(g)\)

1. \(2NaClO_3(s)\xrightarrow{heat}2NaCl(s)+3O_2(g)\)
2. \(2H_2O(l)\xrightarrow{D.C.}2H_2(g)+O_2(g)\)
3. \(2Al(s)+3H_2SO_4(aq)

ightarrow Al_2(SO_4)_3(aq)+3H_2(g)\)

1. \(3Pb(s)+2H_3PO_4(aq)

ightarrow Pb_3(PO_4)_2(s)+3H_2(g)\)

1. \(Mg(s)+2HCl(aq)

ightarrow MgCl_2(aq)+H_2(g)\)

1. \(Ca(s)+H_2SO_4(aq)

ightarrow CaSO_4(aq)+H_2(g)\)