Question

1. write a chemical equation from each of the following word equations.

a) water reacts to produce oxygen and hydrogen
water → hydrogen + oxygen
2h₂o → 2h₂ + o₂
b) lithium and water react to produce lithium hydroxide and hydrogen
lithium + water → lithium hydroxide + hydrogen
li + h₂o → lioh + h₂
c) zinc and hydrogen chloride react to produce zinc chloride and hydrogen
d) potassium iodide and silver nitrate react to produce potassium nitrate and silver iodide (hint: nitrate is no₃⁻. similar to oh⁻, it acts as a unit.)

Explanation:

Step1: Balance equation for water decomposition

The un - balanced equation for water reacting to produce oxygen and hydrogen is $2H_2O
ightarrow 2H_2 + O_2$. This is already balanced as there are 4 hydrogen atoms and 2 oxygen atoms on both sides.

Step2: Balance equation for lithium - water reaction

The un - balanced equation is $Li + H_2O
ightarrow LiOH+H_2$. To balance it, we need 2 moles of $Li$, 2 moles of $H_2O$ to get $2Li + 2H_2O
ightarrow 2LiOH + H_2$.

Step3: Balance equation for zinc - hydrochloric acid reaction

The un - balanced equation is $Zn+HCl
ightarrow ZnCl_2 + H_2$. We need 2 moles of $HCl$ to balance it, so the balanced equation is $Zn + 2HCl
ightarrow ZnCl_2+H_2$.

Step4: Balance equation for potassium iodide - silver nitrate reaction

The un - balanced equation is $KI+AgNO_3
ightarrow KNO_3 + AgI$. This equation is already balanced as there is 1 mole of each element on both sides.

Answer:

a) $2H_2O
ightarrow 2H_2 + O_2$
b) $2Li + 2H_2O
ightarrow 2LiOH + H_2$
c) $Zn + 2HCl
ightarrow ZnCl_2+H_2$
d) $KI+AgNO_3
ightarrow KNO_3 + AgI$