For the questions that follow, consider the following equation:
[tex]\[
Ca(OH)_2(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + 2H_2O(l)
\][/tex]

1. What type of chemical reaction is taking place?
2. If 15 grams of calcium hydroxide reacts, how many grams of calcium chloride are formed?
3. Calculate the concentration of the HCl solution if 80 g of HCl is dissolved in water to make 300 ml of solution.



Answer :

Certainly! Let's approach the problem step by step.

### 1. Type of Chemical Reaction
The reaction provided is:
[tex]\[ Ca(OH)_2(s) + 2HCl(aq) \rightarrow CaCl_2(aq) + 2H_2O(l) \][/tex]

This reaction is a double displacement reaction. In this type of reaction, the ions of the reacting compounds exchange places to form new compounds.

### 2. Grams of Calcium Chloride Formed
#### Step 1: Calculate the moles of Calcium Hydroxide ([tex]\(Ca(OH)_2\)[/tex])
Given:
- Mass of [tex]\(Ca(OH)_2\)[/tex] = 15 grams
- Molar mass of [tex]\(Ca(OH)_2\)[/tex] = 74.093 g/mol

We can calculate the moles of [tex]\(Ca(OH)_2\)[/tex]:
[tex]\[ \text{Moles of } Ca(OH)_2 = \frac{\text{Mass}}{\text{Molar Mass}} = \frac{15 \text{ g}}{74.093 \text{ g/mol}} \][/tex]

After performing the calculation:
[tex]\[ \text{Moles of } Ca(OH)_2 \approx 0.202 \text{ moles} \][/tex]

#### Step 2: Determine moles of Calcium Chloride (CaCl[tex]\(_2\)[/tex]) formed
From the balanced equation, we see that 1 mole of [tex]\(Ca(OH)_2\)[/tex] produces 1 mole of [tex]\(CaCl_2\)[/tex]:
[tex]\[ \text{Moles of } CaCl_2 = \text{Moles of } Ca(OH)_2 \approx 0.202 \text{ moles} \][/tex]

#### Step 3: Calculate the mass of [tex]\( CaCl_2 \)[/tex]
Now, we need to convert the moles of [tex]\(CaCl_2\)[/tex] to grams. Given the molar mass of [tex]\(CaCl_2\)[/tex] = 110.98 g/mol:
[tex]\[ \text{Mass of } CaCl_2 = \text{Moles of } CaCl_2 \times \text{Molar Mass} \][/tex]
[tex]\[ \text{Mass of } CaCl_2 \approx 0.202 \text{ moles} \times 110.98 \text{ g/mol} \][/tex]

Performing the calculation:
[tex]\[ \text{Mass of } CaCl_2 \approx 22.47 \text{ grams} \][/tex]

### 3. Concentration of the HCl Solution
#### Step 1: Calculate the moles of HCl
Given:
- Mass of [tex]\( HCl \)[/tex] = 80 grams
- Molar mass of [tex]\( HCl \)[/tex] = 36.46 g/mol

We can calculate the moles of [tex]\( HCl \)[/tex]:
[tex]\[ \text{Moles of HCl} = \frac{\text{Mass}}{\text{Molar Mass}} = \frac{80 \text{ g}}{36.46 \text{ g/mol}} \][/tex]

After performing the calculation:
[tex]\[ \text{Moles of HCl} \approx 2.194 \text{ moles} \][/tex]

#### Step 2: Calculate the concentration of the HCl solution
Given:
- Volume of the solution = 300 ml = 0.300 liters (since 1000 ml = 1 liter)

Concentration (Molarity) is defined as moles of solute per liter of solution:
[tex]\[ \text{Concentration of HCl} = \frac{\text{Moles of HCl}}{\text{Volume of solution in liters}} \][/tex]
[tex]\[ \text{Concentration of HCl} = \frac{2.194 \text{ moles}}{0.300 \text{ liters}} \][/tex]

After performing the calculation:
[tex]\[ \text{Concentration of HCl} \approx 7.31 \text{ Molar} \][/tex]

### Summary
- The type of chemical reaction is a double displacement reaction.
- When 15 grams of calcium hydroxide reacts, approximately 22.47 grams of calcium chloride is formed.
- The concentration of the HCl solution is approximately 7.31 M (molar).