procedure
1. measure 200 ml of water using a graduated cylinder and carefully pour it into the empty plastic bottle.
2. measure the mass of half an alka-seltzer tablet and the plastic bottle containing 200 ml of water.
3. with the bottle on the lab bench, place a half tablet in the bottle and immediately screw the cap on.
4. wait until the alka-seltzer tablet has completely dissolved. place the closed bottle back on the balance and measure its mass again.

discussion
1. did the mass change after the reaction occurred? why or why not?
2. did a chemical change occur at any time during this experiment? how do you know?

section 6.1.1 formative assessment

reviewing main ideas
1. answer the following questions about the chemical equation shown below:
$2\text{h}_2 + \text{o}_2 \longrightarrow 2\text{h}_2\text{o}$
a. what are the reactants?
b. what is the product?
c. what do we call the number \2\ in front of the $\text{h}_2$ (and $\text{h}_2\text{o}$)?
d. is the reaction balanced?
2. balance the following chemical equations:
a. $\text{fe} + \text{o}_2 \longrightarrow \text{fe}_2\text{o}_3$
b. $\text{h}_2 + \text{cl}_2 \longrightarrow \text{hcl}$
c. $\text{ag} + \text{h}_2\text{s} \longrightarrow \text{ag}_2\text{s} + \text{h}_2$
d. $\text{ch}_4 + \text{o}_2 \longrightarrow \text{co}_2 + \text{h}_2\text{o}$
e. $\text{hgo} \longrightarrow \text{hg} + \text{o}_2$

Question

procedure
1. measure 200 ml of water using a graduated cylinder and carefully pour it into the empty plastic bottle.
2. measure the mass of half an alka-seltzer tablet and the plastic bottle containing 200 ml of water.
3. with the bottle on the lab bench, place a half tablet in the bottle and immediately screw the cap on.
4. wait until the alka-seltzer tablet has completely dissolved. place the closed bottle back on the balance and measure its mass again.

discussion
1. did the mass change after the reaction occurred? why or why not?
2. did a chemical change occur at any time during this experiment? how do you know?

section 6.1.1 formative assessment

reviewing main ideas
1. answer the following questions about the chemical equation shown below:
   $2\text{h}_2 + \text{o}_2 \longrightarrow 2\text{h}_2\text{o}$
   a. what are the reactants?
   b. what is the product?
   c. what do we call the number \2\ in front of the $\text{h}_2$ (and $\text{h}_2\text{o}$)?
   d. is the reaction balanced?
2. balance the following chemical equations:
   a. $\text{fe} + \text{o}_2 \longrightarrow \text{fe}_2\text{o}_3$
   b. $\text{h}_2 + \text{cl}_2 \longrightarrow \text{hcl}$
   c. $\text{ag} + \text{h}_2\text{s} \longrightarrow \text{ag}_2\text{s} + \text{h}_2$
   d. $\text{ch}_4 + \text{o}_2 \longrightarrow \text{co}_2 + \text{h}_2\text{o}$
   e. $\text{hgo} \longrightarrow \text{hg} + \text{o}_2$

Accepted Answer

### 1. a.
# Brief Explanations:
In a chemical equation, reactants are the substances on the left side of the arrow, which undergo the reaction. For the equation $2\text{H}_2 + \text{O}_2
ightarrow 2\text{H}_2\text{O}$, the substances on the left are $\text{H}_2$ (hydrogen) and $\text{O}_2$ (oxygen).
# Answer:
The reactants are $\boldsymbol{\text{H}_2}$ (hydrogen) and $\boldsymbol{\text{O}_2}$ (oxygen).

### 1. b.
# Brief Explanations:
In a chemical equation, the product is the substance formed from the reaction, located on the right side of the arrow. For $2\text{H}_2 + \text{O}_2
ightarrow 2\text{H}_2\text{O}$, the substance on the right is $\text{H}_2\text{O}$ (water).
# Answer:
The product is $\boldsymbol{\text{H}_2\text{O}}$ (water).

### 1. c.
# Brief Explanations:
The number in front of a chemical formula in a chemical equation is called a coefficient. It represents the number of moles (or molecules) of that substance involved in the reaction. Here, the "2" in front of $\text{H}_2$ and $\text{H}_2\text{O}$ is a coefficient.
# Answer:
The number "2" is called a $\boldsymbol{\text{coefficient}}$.

### 1. d.
# Brief Explanations:
To check if a reaction is balanced, we compare the number of each type of atom on both sides. For $2\text{H}_2 + \text{O}_2
ightarrow 2\text{H}_2\text{O}$:
- **Hydrogen (H):** Left side: $2\times2 = 4$ atoms. Right side: $2\times2 = 4$ atoms.
- **Oxygen (O):** Left side: $2$ atoms. Right side: $2\times1 = 2$ atoms.
Since the number of each atom is equal on both sides, the reaction is balanced.
# Answer:
Yes, the reaction is balanced.

### 2. a.
# Explanation:
## Step1: List atom counts
For $ \text{Fe} + \text{O}_2
ightarrow \text{Fe}_2\text{O}_3 $:
- Fe: Left = 1, Right = 2
- O: Left = 2, Right = 3

## Step2: Balance Fe first
Multiply $\text{Fe}$ by 2: $ 2\text{Fe} + \text{O}_2
ightarrow \text{Fe}_2\text{O}_3 $

## Step3: Balance O
Find least common multiple of 2 and 3 (which is 6). Multiply $\text{O}_2$ by 3 and $\text{Fe}_2\text{O}_3$ by 2: $ 2\text{Fe} + 3\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3 $ (now O is balanced, but Fe is not)

## Step4: Re - balance Fe
Multiply $\text{Fe}$ by 4: $ 4\text{Fe} + 3\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3 $
Now, Fe: Left = 4, Right = $2\times2 = 4$; O: Left = $3\times2 = 6$, Right = $2\times3 = 6$. Balanced.
# Answer:
$\boldsymbol{4\text{Fe} + 3\text{O}_2
ightarrow 2\text{Fe}_2\text{O}_3}$

### 2. b.
# Explanation:
## Step1: List atom counts
For $ \text{H}_2 + \text{Cl}_2
ightarrow \text{HCl} $:
- H: Left = 2, Right = 1
- Cl: Left = 2, Right = 1

## Step2: Balance H and Cl
Multiply $\text{HCl}$ by 2: $ \text{H}_2 + \text{Cl}_2
ightarrow 2\text{HCl} $
Now, H: Left = 2, Right = $2\times1 = 2$; Cl: Left = 2, Right = $2\times1 = 2$. Balanced.
# Answer:
$\boldsymbol{\text{H}_2 + \text{Cl}_2
ightarrow 2\text{HCl}}$

### 2. c.
# Explanation:
## Step1: List atom counts
For $ \text{Ag} + \text{H}_2\text{S}
ightarrow \text{Ag}_2\text{S} + \text{H}_2 $:
- Ag: Left = 1, Right = 2
- H: Left = 2, Right = 2
- S: Left = 1, Right = 1

## Step2: Balance Ag
Multiply $\text{Ag}$ by 2: $ 2\text{Ag} + \text{H}_2\text{S}
ightarrow \text{Ag}_2\text{S} + \text{H}_2 $
Now, Ag: Left = 2, Right = 2; H: Left = 2, Right = 2; S: Left = 1, Right = 1. Balanced.
# Answer:
$\boldsymbol{2\text{Ag} + \text{H}_2\text{S}
ightarrow \text{Ag}_2\text{S} + \text{H}_2}$

### 2. d.
# Explanation:
## Step1: List atom counts
For $ \text{CH}_4 + \text{O}_2
ightarrow \text{CO}_2 + \text{H}_2\text{O} $:
- C: Left = 1, Right = 1
- H: Left = 4, Right = 2
- O: Left = 2, Right = $2 + 1=3$

## Step2: Balance H
Multiply $\text{H}_2\text{O}$ by 2: $ \text{CH}_4 + \text{O}_2
ightarrow \text{CO}_2 + 2\text{H}_2\text{O} $

## Step3: Balance O
Now, O on right: $2+2\times1 = 4$. Multiply $\text{O}_2$ by 2: $ \text{CH}_4 + 2\text{O}_2
ightarrow \text{CO}_2 + 2\text{H}_2\text{O} $
Check: C: 1 = 1; H: 4 = $2\times2$; O: $2\times2=4$, $2 + 2\times1 = 4$. Balanced.
# Answer:
$\boldsymbol{\text{CH}_4 + 2\text{O}_2
ightarrow \text{CO}_2 + 2\text{H}_2\text{O}}$

### 2. e.
# Explanation:
## Step1: List atom counts
For $ \text{HgO}
ightarrow \text{Hg} + \text{O}_2 $:
- Hg: Left = 1, Right = 1
- O: Left = 1, Right = 2

## Step2: Balance O
Multiply $\text{HgO}$ by 2: $ 2\text{HgO}
ightarrow \text{Hg} + \text{O}_2 $

## Step3: Balance Hg
Multiply $\text{Hg}$ by 2: $ 2\text{HgO}
ightarrow 2\text{Hg} + \text{O}_2 $
Check: Hg: $2 = 2$; O: $2\times1=2$, $2$. Balanced.
# Answer:
$\boldsymbol{2\text{HgO}
ightarrow 2\text{Hg} + \text{O}_2}$

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

1. a.

Answer:

1. b.