Question

Chemical reactions: Mol/Gram conversions:

a.) According to the following reaction, how many grams of hydrogen gas are necessary to form 0.695 moles ammonia?

N_{2 (g)} + 3H_2(g) 2NH_{3 (g)}.

__________grams hydrogen gas

b.) According to the following reaction, how many moles of calcium chloride will be formed upon the complete reaction of 25.6 grams of calcium hydroxide with excess hydrochloric acid?

Ca(OH)_2(aq) + HCl _(aq) CaCl_{2 (aq)} + 2H₂O _(l)

__________moles calcium chloride

c.) According to the following reaction, how many grams of barium hydroxide are necessary to form 0.699 moles barium chloride?

2HCl _(aq) + Ba(OH)_2(aq) BaCl_2(aq) + 2H₂O _(l)

_________grams barium hydroxide

Answer 1

a)

moles of H2 required = (3/2)*moles of NH3

= (3/2)*0.695 moles

= 1.0425 moles

Molar mass of H2 = 2.016 g/mol

we have below equation to be used:

mass of H2,

m = number of mol * molar mass

= 1.042 mol * 2.016 g/mol

= 2.10 g

Answer: 2.10 g

b)

Molar mass of Ca(OH)2 = 1*MM(Ca) + 2*MM(O) + 2*MM(H)

= 1*40.08 + 2*16.0 + 2*1.008

= 74.096 g/mol

mass of Ca(OH)2 = 25.6 g

mol of Ca(OH)2 = (mass)/(molar mass)

= 25.6/74.096

= 0.3455 mol

From balanced chemical reaction, we see that

when 1 mol of Ca(OH)2 reacts, 1 mol of CaCl2 is formed

mol of CaCl2 formed = moles of Ca(OH)2

= 0.3455 mol

Answer: 0.346 mol

c)

moles of Ba(OH)2 required = moles of BaCl2

= 0.699 mol

Molar mass of Ba(OH)2 = 1*MM(Ba) + 2*MM(O) + 2*MM(H)

= 1*137.3 + 2*16.0 + 2*1.008

= 171.316 g/mol

we have below equation to be used:

mass of Ba(OH)2,

m = number of mol * molar mass

= 0.699 mol * 171.316 g/mol

= 120 g

Answer: 120 g