Question

stoich ws 2

1. how many molecules of hcl must react to form 53 grams of ash₃ according to the following equation:

1 zn₃as₂ + 6 hcl → 2 ash₃ + 3 zncl₂

1. the reaction of hydrogen with oxygen produces water:

2 h₂(g) + 1 o₂(g) → 2 h₂o(g)
a. how many molecules of o₂ are required to react with 2.0 mol h₂?
b. if you have 5.0 grams o₂, how many molecules of h₂ are needed for the reaction?
c. how many molecules of h₂o form when 2.5 x 10²⁶ molecules of o₂ reacts?

1. what mass of hi will react with 3.87 x 10²⁴ molecules of o₂ gas according to the following unbalanced reaction:

4 hi + 1 o₂ → 2 i₂ + 2 h₂o

Explanation:

Problem 1

Step 1: Balance the equation

The balanced equation is \( \text{Zn}_3\text{As}_2 + 6\text{HCl}
ightarrow 2\text{AsH}_3 + 3\text{ZnCl}_2 \)

Step 2: Molar mass of \( \text{AsH}_3 \)

Molar mass of \( \text{As} = 74.92 \, \text{g/mol} \), \( \text{H} = 1.008 \, \text{g/mol} \)
Molar mass of \( \text{AsH}_3 = 74.92 + 3\times1.008 = 77.944 \, \text{g/mol} \)

Step 3: Moles of \( \text{AsH}_3 \)

Moles of \( \text{AsH}_3 = \frac{53 \, \text{g}}{77.944 \, \text{g/mol}} \approx 0.68 \, \text{mol} \)

Step 4: Moles of \( \text{HCl} \)

From the balanced equation, the mole ratio of \( \text{HCl} : \text{AsH}_3 = 6 : 2 = 3 : 1 \)
Moles of \( \text{HCl} = 0.68 \, \text{mol} \times 3 = 2.04 \, \text{mol} \)

Step 5: Molecules of \( \text{HCl} \)

Using Avogadro's number (\( 6.022\times10^{23} \, \text{molecules/mol} \))
Molecules of \( \text{HCl} = 2.04 \, \text{mol} \times 6.022\times10^{23} \, \text{molecules/mol} \approx 1.23\times10^{24} \, \text{molecules} \)

Step 1: Balanced equation

The balanced equation is \( 2\text{H}_2 + \text{O}_2
ightarrow 2\text{H}_2\text{O} \)

Step 2: Mole ratio

Mole ratio of \( \text{O}_2 : \text{H}_2 = 1 : 2 \)

Step 3: Moles of \( \text{O}_2 \)

Moles of \( \text{O}_2 = \frac{2.0 \, \text{mol} \, \text{H}_2}{2} = 1.0 \, \text{mol} \)

Step 4: Molecules of \( \text{O}_2 \)

Molecules of \( \text{O}_2 = 1.0 \, \text{mol} \times 6.022\times10^{23} \, \text{molecules/mol} = 6.022\times10^{23} \, \text{molecules} \)

Step 1: Molar mass of \( \text{O}_2 \)

Molar mass of \( \text{O}_2 = 32.00 \, \text{g/mol} \)

Step 2: Moles of \( \text{O}_2 \)

Moles of \( \text{O}_2 = \frac{5.0 \, \text{g}}{32.00 \, \text{g/mol}} \approx 0.15625 \, \text{mol} \)

Step 3: Mole ratio

Mole ratio of \( \text{H}_2 : \text{O}_2 = 2 : 1 \)
Moles of \( \text{H}_2 = 0.15625 \, \text{mol} \times 2 = 0.3125 \, \text{mol} \)

Step 4: Molecules of \( \text{H}_2 \)

Molecules of \( \text{H}_2 = 0.3125 \, \text{mol} \times 6.022\times10^{23} \, \text{molecules/mol} \approx 1.88\times10^{23} \, \text{molecules} \)

Answer:

\( \approx 1.23\times10^{24} \) molecules of \( \text{HCl} \)

Problem 2a