Question

How many grams of aluminum hydroxide are obtained from 13.7 g of aluminum sulfide??

Answer 1

 For that we need to know something about the chemistry aluminum sulfide and aluminum hydroxide. Aluminum sulfide will react with water to make insoluble aluminum hydroxide and hydrogen sulfide gas. Therefore, we need a balanced chemical equation. 

Al2S3(s) + 6HOH --> 2Al(OH)3(s) + 3H2S(g) 
17.7g ........................ ???g 

17.7g Al2S3 x (1 mol Al2S3 / 150.3 g Al2S3) x (2 mol Al(OH)3 / 1 mol Al2S3) x (78.0g Al(OH)3 / 1 mol Al(OH)3) = 18.4 g Al(OH)3 ...... to three significant digits.

Answer 2

Answer: The mass of aluminium hydroxide obtained is 14.196 grams.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$    .....(1)

Given mass of aluminium sulfide = 13.7 g

Molar mass of aluminium sulfide = 150.158 g/mol

Putting values in equation 1, we get:

$\text{Moles of sodium}=\frac{23g}{150.158g/mol}=0.091mol$

The chemical reaction of aluminium sulfide with water follows the equation:

$Al_2S_3+6H_2O\rightarrow 2Al(OH)_3+3H_2S$

By Stoichiometry of the reaction:

1 mole of aluminium sulfide produces 2 moles of aluminium hydroxide.

So, 0.091 moles of aluminium sulfide will produce = $\frac{2}{1}\times 0.091=0.0182mol$ of aluminium hydroxide.

To calculate the mass of aluminium hydroxide, we use equation 1:

Moles of aluminium hydroxide = 0.0182 moles

Molar mass of aluminium hydroxide = 78 g/mol

Putting values in equation 1, we get:

$0.0182mol=\frac{\text{Mass of aluminium hydroxide}}{78g/mol}\\\\\text{Mass of aluminium hydroxide}=14.196g$

Hence, the mass of aluminium hydroxide obtained is 14.196 grams.