aluminum sulfide reacts with water to form aluminum hydroxide and hydrogen sulfide

Question

a. balance the chem eqn for this rxn
Al2S3+6H2O = 2Al(OH)3+3H2S
b.how many g of water are needed in the rxn to produce al(oh)3?
what is the formula i use here??
c. how many g of al(oh)3 are obtained from 10.5 mg of al2s?
mw of al(oh)3= 78 g/mol
10.5g to g= 0.0105
idk how to get the wt bcos idk the no. of moles :( hoow?
d. how many g of h2s are formed in the rxn?
mw of h2s=34 g/mol.. again idk how to get g :(
e. does the soln to the prblem obey 'law of conservation of mass'? why?
yes i think so cos the energy is being passed only but can never be created or destroyed. ?

Answer 1

aluminum sulfide reacts with water to form aluminum hydroxide and hydrogen sulfide
a. balance the chem eqn for this rxn
Al2S3+6H2O = 2Al(OH)3+3H2S
right.

b.how many g of water are needed in the rxn to produce al(oh)3?
what is the formula i use here??
You can't do without knowint how much Al(OH)3 you want to produce? By the way, you need to find the caps key and use it.

c. how many g of al(oh)3 are obtained from 10.5 mg of al2s?
mw of al(oh)3= 78 g/mol
10.5g to g= 0.0105
idk how to get the wt bcos idk the no. of moles :( hoow?
1.Find mols Al2S3. mols Al2S3 = grams/molar mass = 0.0105/molar mass Al2S3.
2. Convert mols of anything to mols anything by using the coefficients in the balanced equation. mols Al2S3 x (2 mols Al(OH)3/1 mol Al2S3) = mols Al2S3 x 2/1 = ?
3. Convert mols Al(OH)3 to grams by grams Al(OH)3 = mols Al(OH)3 x molar mass Al(OH)3.

d. how many g of h2s are formed in the rxn?
mw of h2s=34 g/mol.. again idk how to get g :(
Done the same way as converting grams Al2S3 to grams Al(OH)3.

e. does the soln to the prblem obey 'law of conservation of mass'? why?
yes i think so cos the energy is being passed only but can never be created or destroyed. ?

Your answer of yes is correct but your reasoning is lousy (you just restated the law). To show it does obey the Law of Conservation of mass add mass of the reactants together and mass of products together. mass reactants and mass of products shold be the same.