Chemical Calculations Worksheet
ADVERTISEMENT
1
2(aq) → _____ Cu(NO
1. _____ Cu(s) + _____ AgNO
)
(aq) + _____ Ag(s)
3
3
2
If 2.5 moles of copper and 5.5 moles of silver nitrate are available to react, what is the limiting
reactant?
(aq) → Cu(NO
Cu(s) + 2AgNO
)
(aq) + 2Ag(s)
3
3
2
2 mol Ag
2.5 mol Cu ×
1 mol Cu = 5 mol Ag possible from 2.5 mol Cu
2 mol Ag
×
5.5 mol AgNO
= 5.5 mol Ag possible from 5.5 mol AgNO
so Cu is the LR
3
2 mol AgNO
3
3
One can compare the other reactant, with the same result. This is not necessary, but is illustrated below:
1 mol Cu(NO
)
3
3
2.5 mol Cu ×
= 2.5 mol Cu(NO
)
possible from 2.5 mol Cu
1 mol Cu
3
3
1 mol Cu(NO
)
3
3
×
5.5 mol AgNO
= 2.75 mol Cu(NO
)
possible from 5.5 mol AgNO
so Cu is
3
2 mol AgNO
3
3
3
3
LR when looking at the other product. This is always true.
O(l) → Ca(OH)
2. CaO(s) + H
(aq)
2
2
How many grams of calcium hydroxide will be formed in this reaction when 4.44 g of calcium oxide
and 7.77 g of water are available to react? Also identify the limiting and excess reactants.
1 mol CaO
1 mol Ca(OH)
74.09 g Ca(OH)
4.44 g CaO ×
×
2
×
2
= 5.87 g Ca(OH)
possible from CaO
2
56.08 g CaO
1 mol CaO
1 mol Ca(OH)
2
1 mol H
O
1 mol Ca(OH)
74.09 g Ca(OH)
O ×
2
×
2
×
2
7.77 g H
= 31.95 g Ca(OH)
possible from H
O
2
2
2
18.02 g H
O
1 mol H
O
1 mol Ca(OH)
2
2
2
So 5.87 g
5.87 g Ca(OH)
is the maximum, theoretical yield, from CaO as the Limiting Reactant, and H
O is in
2
2
excess.
3. Magnesium undergoes a single displacement reaction with hydrochloric acid (aq) to produce
hydrogen gas and magnesium chloride (aq).
Mg(s) + 2HCl(aq) → MgCl
Balanced Equation:
(g) + H
(g) (H is diatomic, Horses)
2
2
How many grams of hydrogen gas will be produced from the reaction of 3.00 g of magnesium with
4.00 g of hydrochloric acid?
1 mol HCl
1 mol H
2.02 g H
7.77 g HCl ×
×
2
×
2
= 0.249 g H
possible from HCl
2
36.45 g HCl
2 mol HCl
1 mol H
2
1 mol Mg
1 mol H
2.02 g H
2
2
3.00 g Mg ×
×
×
= 0.111 g H
possible from Mg
2
24.31 g Mg
1 mol Mg
1 mol H
2
So Mg is the limiting reactant (LR) with 0.111 g of H
forming (theoretical yield) and HCl is in excess.
2
ADVERTISEMENT
0 votes
Related Articles
Related forms
Related Categories
Parent category: Education