Question

given: 2al + 6hcl → 2alcl₃ + 3h₂. if the chemical reaction produces 129 grams of alcl₃, how many grams of h₂ are also produced? a. 1.22 b. 2.92 c. 3.02 d. 3.65

Explanation:

Step1: Calculate molar mass of AlCl₃

The molar mass of AlCl₃: $M_{AlCl_3}=26.98 + 3\times35.45=133.33\ g/mol$

Step2: Find moles of AlCl₃

$n_{AlCl_3}=\frac{m_{AlCl_3}}{M_{AlCl_3}}=\frac{129\ g}{133.33\ g/mol}\approx0.9675\ mol$

Step3: Determine mole - ratio

From the balanced equation $2Al + 6HCl
ightarrow2AlCl_3+3H_2$, the mole - ratio of $AlCl_3$ to $H_2$ is $\frac{n_{H_2}}{n_{AlCl_3}}=\frac{3}{2}$

Step4: Calculate moles of H₂

$n_{H_2}=\frac{3}{2}n_{AlCl_3}=\frac{3}{2}\times0.9675\ mol = 1.45125\ mol$

Step5: Calculate mass of H₂

The molar mass of $H_2$ is $M_{H_2}=2\times1.008\ g/mol = 2.016\ g/mol$. So, $m_{H_2}=n_{H_2}\times M_{H_2}=1.45125\ mol\times2.016\ g/mol\approx2.92\ g$

Answer:

B. 2.92