Question

hydrogen peroxide can be used to disinfect and clean surfaces around the home. it breaks down over time into oxygen gas and water. consider the following reaction: some amount of hydrogen peroxide (h₂o₂) breaks down to produce 10 molecules of oxygen (o₂) and 20 molecules of water (h₂o). complete the table below. chemical element | number of atoms in the reaction h | o | during this reaction, how many molecules of hydrogen peroxide (h₂o₂) react?

Explanation:

Part 1: Completing the table for number of atoms (H and O)

For Hydrogen (H):

Step1: Find H from $H_2O$

Each $H_2O$ has 2 H atoms. There are 20 $H_2O$ molecules. So H from $H_2O$: $2\times20 = 40$.
(No H in $O_2$ or reactant $H_2O_2$ considered here for product side, but since reaction is balanced, reactant $H_2O_2$ will supply H. But for counting in reaction (product side, and reactant side should match), so total H atoms: 40.

For Oxygen (O):

Step1: Find O from $O_2$

Each $O_2$ has 2 O atoms. 10 $O_2$ molecules: $2\times10 = 20$.

Step2: Find O from $H_2O$

Each $H_2O$ has 1 O atom. 20 $H_2O$ molecules: $1\times20 = 20$.

Step3: Total O atoms

Sum O from $O_2$ and $H_2O$: $20 + 20 = 40$.

Part 2: Number of $H_2O_2$ molecules reacting

The balanced reaction for decomposition of $H_2O_2$ is: $2H_2O_2
ightarrow 2H_2O + O_2$ (but let's derive from products).
From products: 20 $H_2O$ (each has 2 H, so 40 H) and 10 $O_2$ (20 O) + 20 O from $H_2O$ = 40 O.
Each $H_2O_2$ has 2 H and 2 O. Let number of $H_2O_2$ be $x$.
For H: $2x = 40$ (from earlier, total H is 40) $\Rightarrow x = 20$.
Check O: $2x = 40$ (total O is 40) $\Rightarrow x = 20$. Also, from the product $O_2$ (10 molecules, 20 O) and $H_2O$ (20 O), total O 40. Each $H_2O_2$ has 2 O, so $2x = 40 \Rightarrow x = 20$. Also, from the reaction stoichiometry: if 20 $H_2O$ and 10 $O_2$ are produced, the reaction is $2H_2O_2
ightarrow 2H_2O + O_2$ scaled? Wait, no: Let's see moles (molecules) ratio.
From $H_2O$: 20 molecules. From $O_2$: 10 molecules. The balanced equation is $2H_2O_2
ightarrow 2H_2O + O_2$. So for 2 $H_2O$ and 1 $O_2$, we need 2 $H_2O_2$. Here, $H_2O$ is 20 (which is 10 times 2) and $O_2$ is 10 (10 times 1). So $H_2O_2$ should be 10 times 2 = 20.

Answer:

s:

• H atoms: 40
• O atoms: 40
• $H_2O_2$ molecules: 20

(For the table: H: 40, O: 40; and $H_2O_2$: 20)