Question

question #4- use the balanced equation to answer the following question.
how many moles of oxygen (o₂) will be consumed if 7.50 moles of aluminum oxide (al₂o₃) are produced?
4 al + 3 o₂ → 2 al₂o₃
15.0 moles
22.5 moles
11.3 moles
5.00 moles
question #5- use the balanced equation to answer the following question.
how many moles of aluminum oxide (al₂o₃) can be produced with 83 grams of aluminum (al)?
4 al + 3 o₂ → 2 al₂o₃
3.1 moles
1.2 moles
1.5 moles
8.5 moles

Explanation:

(Question #4):

Step1: Identify mole ratio

From $4\text{Al} + 3\text{O}_2
ightarrow 2\text{Al}_2\text{O}_3$, mole ratio of $\text{O}_2$ to $\text{Al}_2\text{O}_3$ is $\frac{3}{2}$.

Step2: Calculate moles of $\text{O}_2$

Moles of $\text{O}_2 = 7.50 \times \frac{3}{2}$
$= 11.25 \approx 11.3$

(Question #5):

Step1: Find molar mass of Al

Molar mass of $\text{Al} = 26.98\ \text{g/mol}$

Step2: Calculate moles of Al

Moles of $\text{Al} = \frac{83}{26.98} \approx 3.076$

Step3: Identify mole ratio

From $4\text{Al} + 3\text{O}_2
ightarrow 2\text{Al}_2\text{O}_3$, mole ratio of $\text{Al}_2\text{O}_3$ to $\text{Al}$ is $\frac{2}{4} = \frac{1}{2}$.

Step4: Calculate moles of $\text{Al}_2\text{O}_3$

Moles of $\text{Al}_2\text{O}_3 = 3.076 \times \frac{1}{2} \approx 1.5$

Answer:

Question #4: 11.3 moles
Question #5: 1.5 moles