Question

q.5. balance the following chemical equations.
a) alcl₃ + h₂o → al(oh)₃ + hcl
b) c₃h₈ + o₂ → co₂ + h₂o
c) al + feo → al₂o₃ + fe
d) s₈ + o₂ → __so₃
e) c₇h₆o₂ + o₂ → co₂ + h₂o
f) baf₂ + k₃po₄ → ba₃(po₄)₂ + kf
g) fecl₃ + naoh → fe(oh)₃ + nacl
h) k₃po₄ + hcl → kcl + h₃po₄
i) cabr₂ + na₃p → ca₃p₂ + nabr
j) b₂br₆ + hno₃ → b(no₃)₃ + hbr

Explanation:

a)

Step1: Balance Al

$$AlCl_3 + H_2O ightarrow Al(OH)_3 + HCl$$

Al is balanced (1 on each side).

Step2: Balance Cl

$$AlCl_3 + H_2O ightarrow Al(OH)_3 + 3HCl$$

Cl: 3 on left, 3 on right.

Step3: Balance H and O

$$AlCl_3 + 3H_2O ightarrow Al(OH)_3 + 3HCl$$

H: 6 on left (32), 6 on right (3 + 3). O: 3 on left (31), 3 on right (3*1).

b)

Step1: Balance C

$$C_3H_8 + O_2 ightarrow 3CO_2 + H_2O$$

C: 3 on left, 3 on right.

Step2: Balance H

$$C_3H_8 + O_2 ightarrow 3CO_2 + 4H_2O$$

H: 8 on left, 8 on right (4*2).

Step3: Balance O

$$C_3H_8 + 5O_2 ightarrow 3CO_2 + 4H_2O$$

O: 10 on left (52), 10 on right (32 + 4*1).

c)

Step1: Balance Al

$$2Al + FeO ightarrow Al_2O_3 + Fe$$

Al: 2 on left, 2 on right.

Step2: Balance O

$$2Al + 3FeO ightarrow Al_2O_3 + 3Fe$$

O: 3 on left (3*1), 3 on right. Fe: 3 on left, 3 on right.

d)

Step1: Balance S

$$S_8 + O_2 ightarrow 8SO_3$$

S: 8 on left, 8 on right.

Step2: Balance O

$$S_8 + 12O_2 ightarrow 8SO_3$$

O: 24 on left (122), 24 on right (83).

e)

Step1: Balance C

$$C_7H_6O_2 + O_2 ightarrow 7CO_2 + H_2O$$

C: 7 on left, 7 on right.

Step2: Balance H

$$C_7H_6O_2 + O_2 ightarrow 7CO_2 + 3H_2O$$

H: 6 on left, 6 on right (3*2).

Step3: Balance O

$$C_7H_6O_2 + 7O_2 ightarrow 7CO_2 + 3H_2O$$

O: 16 on left (2 + 72), 16 on right (72 + 3*1).

f)

Step1: Balance Ba

$$3BaF_2 + K_3PO_4 ightarrow Ba_3(PO_4)_2 + KF$$

Ba: 3 on left, 3 on right.

Step2: Balance PO₄

$$3BaF_2 + 2K_3PO_4 ightarrow Ba_3(PO_4)_2 + KF$$

PO₄: 2 on left, 2 on right.

Step3: Balance K and F

$$3BaF_2 + 2K_3PO_4 ightarrow Ba_3(PO_4)_2 + 6KF$$

K: 6 on left (23), 6 on right. F: 6 on left (32), 6 on right (6*1).

g)

Step1: Balance Fe

$$FeCl_3 + NaOH ightarrow Fe(OH)_3 + NaCl$$

Fe: 1 on left, 1 on right.

Step2: Balance Cl

$$FeCl_3 + NaOH ightarrow Fe(OH)_3 + 3NaCl$$

Cl: 3 on left, 3 on right.

Step3: Balance Na and OH

$$FeCl_3 + 3NaOH ightarrow Fe(OH)_3 + 3NaCl$$

Na: 3 on left, 3 on right. OH: 3 on left, 3 on right.

h)

Step1: Balance K

$$K_3PO_4 + HCl ightarrow 3KCl + H_3PO_4$$

K: 3 on left, 3 on right.

Step2: Balance Cl

$$K_3PO_4 + 3HCl ightarrow 3KCl + H_3PO_4$$

Cl: 3 on left, 3 on right.

i)

Step1: Balance Ca

$$3CaBr_2 + Na_3P ightarrow Ca_3P_2 + NaBr$$

Ca: 3 on left, 3 on right.

Step2: Balance P

$$3CaBr_2 + 2Na_3P ightarrow Ca_3P_2 + NaBr$$

P: 2 on left, 2 on right.

Step3: Balance Na and Br

$$3CaBr_2 + 2Na_3P ightarrow Ca_3P_2 + 6NaBr$$

Na: 6 on left (23), 6 on right. Br: 6 on left (32), 6 on right.

j)

Step1: Balance B

$$B_2Br_6 + HNO_3 ightarrow 2B(NO_3)_3 + HBr$$

B: 2 on left, 2 on right.

Step2: Balance NO₃

$$B_2Br_6 + 6HNO_3 ightarrow 2B(NO_3)_3 + HBr$$

NO₃: 6 on left, 6 on right.

Step3: Balance H and Br

$$B_2Br_6 + 6HNO_3 ightarrow 2B(NO_3)_3 + 6HBr$$

H: 6 on left, 6 on right. Br: 6 on left, 6 on right.

Answer:

a) \(1\ AlCl_3 + 3\ H_2O
ightarrow 1\ Al(OH)_3 + 3\ HCl\)
b) \(1\ C_3H_8 + 5\ O_2
ightarrow 3\ CO_2 + 4\ H_2O\)
c) \(2\ Al + 3\ FeO
ightarrow 1\ Al_2O_3 + 3\ Fe\)
d) \(1\ S_8 + 12\ O_2
ightarrow 8\ SO_3\)
e) \(1\ C_7H_6O_2 + 7\ O_2
ightarrow 7\ CO_2 + 3\ H_2O\)
f) \(3\ BaF_2 + 2\ K_3PO_4
ightarrow 1\ Ba_3(PO_4)_2 + 6\ KF\)
g) \(1\ FeCl_3 + 3\ NaOH
ightarrow 1\ Fe(OH)_3 + 3\ NaCl\)
h) \(1\ K_3PO_4 + 3\ HCl
ightarrow 3\ KCl + 1\ H_3PO_4\)
i) \(3\ CaBr_2 + 2\ Na_3P
ightarrow 1\ Ca_3P_2 + 6\ NaBr\)
j) \(1\ B_2Br_6 + 6\ HNO_3
ightarrow 2\ B(NO_3)_3 + 6\ HBr\)