Question

Use the chemical equation to complete the activity. 2Cu+S→Cu2S Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams

Answer 1

To analyze the reaction given by the equation \( 2 \text{Cu} + \text{S} \rightarrow \text{Cu}_2\text{S} \), we can determine how much reactants (copper and sulfur) are involved and how they relate to the product (copper sulfide) produced.

### Given Data
- Mass of copper (Cu) = 12.7 grams

### Molar Mass Calculations
1. Calculate the molar mass of copper (Cu):
- Molar mass of Cu = 63.55 g/mol

2. Calculate the molar mass of sulfur (S):
- Molar mass of S = 32.07 g/mol

3. Calculate the molar mass of copper sulfide (Cu2S):
- Molar mass of Cu2S = (2 × 63.55) + 32.07 = 127.10 + 32.07 = 159.17 g/mol

### Convert grams of copper to moles
Using the formula:
\[
\text{moles} = \frac{\text{mass}}{\text{molar mass}}
\]

Calculate moles of Cu:
\[
\text{moles of Cu} = \frac{12.7 \text{ g}}{63.55 \text{ g/mol}} \approx 0.200 \text{ moles Cu}
\]

### Determine the stoichiometry
The balanced equation shows that:
- 2 moles of Cu react with 1 mole of S to produce 1 mole of Cu2S.

From the balanced equation:
- \( 2 \text{ moles Cu} : 1 \text{ mole S} : 1 \text{ mole Cu}_2\text{S} \)

### Determine moles of sulfur needed
To find the moles of sulfur (S) needed for the reaction with 0.200 moles of copper:
\[
\text{moles of S} = \frac{0.200 \text{ moles Cu}}{2} = 0.100 \text{ moles S}
\]

### Convert moles of sulfur to grams
Calculate the grams of sulfur needed:
\[
\text{mass of S} = \text{moles of S} \times \text{molar mass of S} = 0.100 \text{ moles} \times 32.07 \text{ g/mol} \approx 3.21 \text{ g}
\]

### Final Results
The scientist would need:
- **3.21 grams of sulfur (S)** to react completely with **12.7 grams of copper (Cu)**.

This would produce:
- **0.100 moles of Cu2S**, which corresponds to approximately **15.87 grams of Cu2S**.