Question

c₃h₈(g) + o₂(g) co₂(g) + h₂o(l)

zn(s) + hcl(aq) zncl₂(aq) + h₂(g)

naoh(aq) + h₂so₄(aq) na₂so₄(aq) + h₂o(l)

na₂so₄(aq) + bacl₂(aq) baso₄(s) + nacl(aq)

:: 2, 1, 1, 2 :: 1, 2, 1, 1 :: 1, 1, 1, 2 :: 1, 5, 3, 4

Explanation:

Step1: Balance the first equation \(C_{3}H_{8}(g)+O_{2}(g)\to CO_{2}(g)+H_{2}O(l)\)

• Balance \(C\): There are 3 \(C\) atoms in \(C_{3}H_{8}\), so put 3 in front of \(CO_{2}\).
• Balance \(H\): There are 8 \(H\) atoms in \(C_{3}H_{8}\), so put 4 in front of \(H_{2}O\).
• Balance \(O\): Now, on the right - hand side, there are \(3\times2 + 4\times1=10\) \(O\) atoms. So put 5 in front of \(O_{2}\). The balanced equation is \(C_{3}H_{8}(g)+5O_{2}(g)=3CO_{2}(g)+4H_{2}O(l)\)

Step2: Balance the second equation \(Zn(s)+HCl(aq)\to ZnCl_{2}(aq)+H_{2}(g)\)

• Balance \(Cl\): There are 2 \(Cl\) atoms in \(ZnCl_{2}\), so put 2 in front of \(HCl\).
• Balance \(H\): After putting 2 in front of \(HCl\), the \(H\) atoms are balanced. The balanced equation is \(Zn(s)+2HCl(aq)=ZnCl_{2}(aq)+H_{2}(g)\)

Step3: Balance the third equation \(NaOH(aq)+H_{2}SO_{4}(aq)\to Na_{2}SO_{4}(aq)+H_{2}O(l)\)

• Balance \(Na\): There are 2 \(Na\) atoms in \(Na_{2}SO_{4}\), so put 2 in front of \(NaOH\).
• Balance \(H\) and \(O\): After putting 2 in front of \(NaOH\), the equation is balanced. The balanced equation is \(2NaOH(aq)+H_{2}SO_{4}(aq)=Na_{2}SO_{4}(aq)+2H_{2}O(l)\)

Step4: Balance the fourth equation \(Na_{2}SO_{4}(aq)+BaCl_{2}(aq)\to BaSO_{4}(s)+NaCl(aq)\)

• Balance \(Na\): There are 2 \(Na\) atoms in \(Na_{2}SO_{4}\), so put 2 in front of \(NaCl\). The balanced equation is \(Na_{2}SO_{4}(aq)+BaCl_{2}(aq)=BaSO_{4}(s)+2NaCl(aq)\)

Answer:

1. \(1,5,3,4\)
2. \(1,2,1,1\)
3. \(2,1,1,2\)
4. \(1,1,1,2\)