Question

use with textbook pages 206 - 211.
balancing equations
starting with the skeleton equations, balance the following equations by adding coefficients where appropriate.

1. ( h_2 + f_2 \to hf )
2. ( sn + o_2 \to sno )
3. ( mgcl_2 \to mg + cl_2 )
4. ( kno_3 \to kno_2 + o_2 )
5. ( bn + f_2 \to bf_3 + n_2 )
6. ( cui_2 + fe \to fei_2 + cu )
7. ( li + h_2o \to lioh + h_2 )
8. ( nh_3 + o_2 \to n_2 + h_2o )
9. ( v_2o_5 + ca \to cao + v )
10. ( c_9h_8o_4 + o_2 \to co_2 + h_2o )
11. ( h_2s + pbcl_2 \to pbs + hcl )
12. ( c_3h_7oh + o_2 \to co_2 + h_2o )
13. ( zn + cuso_4 \to cu + znso_4 )
14. ( c_6h_{12}o_6 + o_2 \to co_2 + h_2o )
15. ( c_2h_5oh + o_2 \to co_2 + h_2o )
16. ( al + h_2so_4 \to h_2 + al_2(so_4)_3 )
17. ( fecl_3 + ca(oh)_2 \to fe(oh)_3 + cacl_2 )
18. ( pb(no_3)_2 + k_2cro_4 \to pbcro_4 + kno_3 )
19. ( cd(no_3)_2 + (nh_4)_2s \to cds + nh_4no_3 )
20. ( ca(oh)_2 + nh_4cl \to nh_3 + cacl_2 + h_2o )

Explanation:

Step1: Balance hydrogen and fluorine

For \(H_2 + F_2
ightarrow HF\), there are 2 H atoms and 2 F atoms on the left. On the right, we need 2 HF to balance, so \(H_2+F_2 = 2HF\).

Step2: Balance oxygen and tin

For \(Sn+O_2
ightarrow SnO\), there are 2 O atoms on the left. So we need 2 SnO on the right. Then balance Sn: \(2Sn + O_2=2SnO\).

Step3: Already balanced

For \(MgCl_2
ightarrow Mg + Cl_2\), the equation is already balanced as written.

Step4: Balance oxygen

For \(KNO_3
ightarrow KNO_2+O_2\), there are 3 O atoms on the left and 4 O atoms on the right (2 from \(KNO_2\) and 2 from \(O_2\)). Multiply \(KNO_3\) by 2 and \(KNO_2\) by 2: \(2KNO_3 = 2KNO_2+O_2\).

Step5: Balance boron, nitrogen and fluorine

For \(BN+F_2
ightarrow BF_3+N_2\), balance N first: 2 BN. Then balance B: 2 BN gives 2 \(BF_3\). Then balance F: \(2BN + 3F_2=2BF_3+N_2\).

Step6: Already balanced

For \(CuI_2+Fe
ightarrow FeI_2+Cu\), the equation is already balanced as written.

Step7: Balance hydrogen and lithium

For \(Li + H_2O
ightarrow LiOH+H_2\), balance H: 2 \(H_2O\) gives 2 \(LiOH\). Then balance Li: \(2Li+2H_2O = 2LiOH + H_2\).

Step8: Balance nitrogen and hydrogen

For \(NH_3+O_2
ightarrow N_2+H_2O\), balance N: 2 \(NH_3\). Then balance H: 2 \(NH_3\) gives 3 \(H_2O\). Then balance O: \(4NH_3+3O_2 = 2N_2+6H_2O\).

Step9: Balance oxygen and vanadium

For \(V_2O_5+Ca
ightarrow CaO+V\), balance O: 5 \(CaO\). Then balance Ca: 5 Ca. Then balance V: \(V_2O_5+5Ca = 5CaO+2V\).

Step10: Balance carbon, hydrogen and oxygen

For \(C_9H_8O_4+O_2
ightarrow CO_2+H_2O\), balance C: 9 \(CO_2\). Balance H: 4 \(H_2O\). Then balance O: \(C_9H_8O_4+9O_2 = 9CO_2+4H_2O\).

Step11: Balance hydrogen and chlorine

For \(H_2S+PbCl_2
ightarrow PbS+HCl\), balance H and Cl: \(H_2S+PbCl_2 = PbS+2HCl\).

Step12: Balance carbon, hydrogen and oxygen

For \(C_3H_7OH+O_2
ightarrow CO_2+H_2O\), balance C: 3 \(CO_2\). Balance H: 4 \(H_2O\). Then balance O: \(2C_3H_7OH+9O_2 = 6CO_2+8H_2O\).

Step13: Already balanced

For \(Zn+CuSO_4
ightarrow Cu+ZnSO_4\), the equation is already balanced as written.

Step14: Balance carbon, hydrogen and oxygen

For \(C_6H_{12}O_6+O_2
ightarrow CO_2+H_2O\), balance C: 6 \(CO_2\). Balance H: 6 \(H_2O\). Then balance O: \(C_6H_{12}O_6+6O_2 = 6CO_2+6H_2O\).

Step15: Balance carbon, hydrogen and oxygen

For \(C_2H_5OH+O_2
ightarrow CO_2+H_2O\), balance C: 2 \(CO_2\). Balance H: 3 \(H_2O\). Then balance O: \(C_2H_5OH+3O_2 = 2CO_2+3H_2O\).

Step16: Balance aluminum, hydrogen and sulfate

For \(Al+H_2SO_4
ightarrow H_2+Al_2(SO_4)_3\), balance sulfate: 3 \(H_2SO_4\). Then balance H: 3 \(H_2SO_4\) gives 3 \(H_2\). Then balance Al: \(2Al+3H_2SO_4 = 3H_2+Al_2(SO_4)_3\).

Step17: Balance iron, chlorine, calcium and hydroxide

For \(FeCl_3+Ca(OH)_2
ightarrow Fe(OH)_3+CaCl_2\), balance Cl: 2 \(FeCl_3\) and 3 \(CaCl_2\). Then balance Ca: 3 \(Ca(OH)_2\). Then balance Fe: \(2FeCl_3+3Ca(OH)_2 = 2Fe(OH)_3+3CaCl_2\).

Step18: Balance lead, nitrate, potassium and chromate

For \(Pb(NO_3)_2+K_2CrO_4
ightarrow PbCrO_4+KNO_3\), balance nitrate: 2 \(KNO_3\). Then balance K: \(Pb(NO_3)_2+K_2CrO_4 = PbCrO_4+2KNO_3\).

Step19: Already balanced

For \(Cd(NO_3)_2+(NH_4)_2S
ightarrow CdS+NH_4NO_3\), the equation is already balanced as written.

Step20: Balance calcium, hydroxide, ammonium and chlorine

For \(Ca(OH)_2+NH_4Cl
ightarrow NH_3+CaCl_2+H_2O\), balance Cl: 2 \(NH_4Cl\). Then balance N: 2 \(NH_3\). Then balance H and O: \(Ca(OH)_2+2NH_4Cl = 2NH_3+CaCl_2+2H_2O\).

Answer:

1. \(H_2+F_2 = 2HF\)
2. \(2Sn + O_2=2SnO\)
3. \(MgCl_2

ightarrow Mg + Cl_2\)

1. \(2KNO_3 = 2KNO_2+O_2\)
2. \(2BN + 3F_2=2BF_3+N_2\)
3. \(CuI_2+Fe

ightarrow FeI_2+Cu\)

1. \(2Li+2H_2O = 2LiOH + H_2\)
2. \(4NH_3+3O_2 = 2N_2+6H_2O\)
3. \(V_2O_5+5Ca = 5CaO+2V\)
4. \(C_9H_8O_4+9O_2 = 9CO_2+4H_2O\)
5. \(H_2S+PbCl_2 = PbS+2HCl\)
6. \(2C_3H_7OH+9O_2 = 6CO_2+8H_2O\)
7. \(Zn+CuSO_4

ightarrow Cu+ZnSO_4\)

1. \(C_6H_{12}O_6+6O_2 = 6CO_2+6H_2O\)
2. \(C_2H_5OH+3O_2 = 2CO_2+3H_2O\)
3. \(2Al+3H_2SO_4 = 3H_2+Al_2(SO_4)_3\)
4. \(2FeCl_3+3Ca(OH)_2 = 2Fe(OH)_3+3CaCl_2\)
5. \(Pb(NO_3)_2+K_2CrO_4 = PbCrO_4+2KNO_3\)
6. \(Cd(NO_3)_2+(NH_4)_2S

ightarrow CdS+NH_4NO_3\)

1. \(Ca(OH)_2+2NH_4Cl = 2NH_3+CaCl_2+2H_2O\)