Question

balancing and types of reactions practice
balance the equation:
□al₂(so₄)₃ + □ca(oh)₂ → □al(oh)₃ + □caso₄
type of reaction:

Explanation:

Step1: Balance Al atoms

Left side has 2 Al (in $\ce{Al2(SO4)3}$), right side has 1 Al (in $\ce{Al(OH)3}$). So put 2 in front of $\ce{Al(OH)3}$. Now equation: $\ce{Al2(SO4)3 + Ca(OH)2 -> 2Al(OH)3 + CaSO4}$

Step2: Balance $\ce{SO4^{2-}}$ ions

Left side has 3 $\ce{SO4^{2-}}$ (in $\ce{Al2(SO4)3}$), right side has 1 $\ce{SO4^{2-}}$ (in $\ce{CaSO4}$). So put 3 in front of $\ce{CaSO4}$. Now equation: $\ce{Al2(SO4)3 + Ca(OH)2 -> 2Al(OH)3 + 3CaSO4}$

Step3: Balance Ca atoms

Right side has 3 Ca (in $\ce{3CaSO4}$), left side has 1 Ca (in $\ce{Ca(OH)2}$). So put 3 in front of $\ce{Ca(OH)2}$. Now check OH: Left side has $3\times2 = 6$ OH, right side has $2\times3 = 6$ OH. Balanced equation: $\ce{Al2(SO4)3 + 3Ca(OH)2 -> 2Al(OH)3 + 3CaSO4}$

Step4: Determine reaction type

This is a double - displacement reaction (ions exchange: $\ce{Al^{3+}}$ with $\ce{OH^{-}}$, $\ce{Ca^{2+}}$ with $\ce{SO4^{2-}}$), also a precipitation reaction (forms $\ce{Al(OH)3}$ and $\ce{CaSO4}$ which can be precipitates), but mainly double - displacement.

Answer:

Balanced equation: $\boldsymbol{\ce{1Al2(SO4)3 + 3Ca(OH)2 -> 2Al(OH)3 + 3CaSO4}}$; Type of reaction: Double - Displacement (or Precipitation)