Question

single replacement - an element replaces another element in a compound.

• kcl + f₂ → kf + cl₂
• mg + hcl → mgcl₂ + h₂
• cu + agno₃ → cu(no₃)₂ + ag

2kcl + f₂
2kf + cl₂

Explanation:

Step1: Balance the first equation (KCl + F₂ → KF + Cl₂)

• First, look at the number of K atoms: left has 1 (in KCl), right has 1 (in KF). So K is balanced for now.
• For Cl: left has 1 (in KCl), right has 2 (in Cl₂). So we need 2 KCl on the left.
• For F: left has 2 (in F₂), right has 1 (in KF). So we need 2 KF on the right.
• Now rewrite the equation with coefficients: \( 2\text{KCl} + \text{F}_2

ightarrow 2\text{KF} + \text{Cl}_2 \)

Step2: Balance the second equation (Mg + HCl → MgCl₂ + H₂)

• Mg: left 1, right 1 (balanced).
• Cl: left 1 (in HCl), right 2 (in MgCl₂). So we need 2 HCl on the left.
• H: left 2 (in 2 HCl), right 2 (in H₂) (balanced now).
• Balanced equation: \( \text{Mg} + 2\text{HCl}

ightarrow \text{MgCl}_2 + \text{H}_2 \)

Step3: Balance the third equation (Cu + AgNO₃ → Cu(NO₃)₂ + Ag)

• Cu: left 1, right 1 (balanced).
• NO₃⁻: left 1 (in AgNO₃), right 2 (in Cu(NO₃)₂). So we need 2 AgNO₃ on the left.
• Ag: left 2 (in 2 AgNO₃), right 1 (in Ag). So we need 2 Ag on the right.
• Balanced equation: \( \text{Cu} + 2\text{AgNO}_3

ightarrow \text{Cu(NO}_3\text{)}_2 + 2\text{Ag} \)

Answer:

• Balanced \( \text{KCl} + \text{F}_2 \) reaction: \( 2\text{KCl} + \text{F}_2 = 2\text{KF} + \text{Cl}_2 \)
• Balanced \( \text{Mg} + \text{HCl} \) reaction: \( \text{Mg} + 2\text{HCl} = \text{MgCl}_2 + \text{H}_2 \uparrow \)
• Balanced \( \text{Cu} + \text{AgNO}_3 \) reaction: \( \text{Cu} + 2\text{AgNO}_3 = \text{Cu(NO}_3\text{)}_2 + 2\text{Ag} \)