Concept explainers
For each of the following unbalanced chemical equations, suppose that exactly 15.0 g of each reactant are taken. Using Before− Change−After (BCA) tables, determine which reactant is limiting, and calculate what mass of each product is expected. (Assume that the limiting reactant is completely consumed.)
msp;
msp;
msp;
msp;
(a)
Interpretation:
Using Before-Change-After (BCA) tables, the limiting reactant should be determined in the given unbalanced equation, supposing that exactly
Concept Introduction:
To determine how much product can be formed from a given mixture of reactants, we have to look for the reactant that is limiting; the one that runs out first and thus limits the amount of product that can form. The reactant that runs out first limiting the amount of products form is called the limiting reactant or limiting reagent.
To determine limiting reactant, first we should have a balanced equation. Then we include the information in Before-Change-After table.
E.g
Balanced equation
Before
Change
After
Starting amounts of reactants are presented in before row. The change row represents how much of each substance reacts or is produced. The after row represents how much of each substance remain in the final reaction mixture. The ratio of the numbers in the change row has to be the same as the ratio of the coefficients in the balanced equation.
Answer to Problem 50QAP
The limiting reagent is HCl.
Mass of AlCl3 produce =
Mass of H2 produce =
Explanation of Solution
Number of moles of Al =
Number of moles of HCl =
Possibility I: if Al runs out first
Balanced equation
Before
Change
_________________________________________________________________________
After
Possibility II: if HCl runs out first
Balanced equation
Before
Change
_________________________________________________________________________
After
According to BCA tables, Al is not the limiting reactant as to react with all the Al we need
Mass of AlCl3 produce =
Mass of H2 produce =
(b)
Interpretation:
Using Before-Change-After (BCA) tables, the limiting reactant should be determined in the given unbalanced equation, supposing that exactly
Concept Introduction:
To determine how much product can be formed from a given mixture of reactants, we have to look for the reactant that is limiting; the one that runs out first and thus limits the amount of product that can form. The reactant that runs out first limiting the amount of products form is called the limiting reactant or limiting reagent.
To determine limiting reactant, first we should have a balanced equation. Then we include the information in Before-Change-After table.
E.g
Balanced equation
Before
Change
After
Starting amounts of reactants are presented in before row. The change row represents how much of each substance reacts or is produced. The after row represents how much of each substance remain in the final reaction mixture. The ratio of the numbers in the change row has to be the same as the ratio of the coefficients in the balanced equation.
Answer to Problem 50QAP
The limiting reagent is NaOH
Mass of Na2 CO3 produce =
Mass of H2 O produce =
Explanation of Solution
Number of moles of NaOH =
Number of moles of CO2 =
Possibility I: if NaOH runs out first
Balanced equation
Before
Change
______________________________________________________________________________
After
Possibility II: if CO2 runs out first
Balanced equation
Befor
Change
_________________________________________________________________________
After
According to BCA tables, CO2 is not the limiting reactant as to react with all the NaOH, we need
Mass of Na2 CO3 produce =
Mass of H2 O produce =
(c)
Interpretation:
Using Before-Change-After (BCA) tables, the limiting reactant should be determined in the given unbalanced equation, supposing that exactly
Concept Introduction:
To determine how much product can be formed from a given mixture of reactants, we have to look for the reactant that is limiting; the one that runs out first and thus limits the amount of product that can form. The reactant that runs out first limiting the amount of products form is called the limiting reactant or limiting reagent.
To determine limiting reactant, first we should have a balanced equation. Then we include the information in Before-Change-After table.
E.g
Balanced equation
Before
Change
After
Starting amounts of reactants are presented in before row. The change row represents how much of each substance reacts or is produced. The after row represents how much of each substance remain in the final reaction mixture. The ratio of the numbers in the change row has to be the same as the ratio of the coefficients in the balanced equation.
Answer to Problem 50QAP
The limiting reagent is Pb(NO3 )2 Mass of PbCl2 produce =
Mass of HNO3 produce =
Explanation of Solution
Number of moles of Pb(NO3 )2 =
Number of moles of HCl =
Possibility I: if Pb(NO3 )2 runs out first
Balanced equation
Before
Change
______________________________________________________________________________
After
Possibility II: if HCl runs out first
Balanced equation
Before
Change
_________________________________________________________________________
After
According to BCA tables, HCl is not the limiting reactant as, to react with all the HCl, we need
Mass of PbCl2 produce =
Mass of HNO3 produce =
(d)
Interpretation:
Using Before-Change-After (BCA) tables, the limiting reactant should be determined in the given unbalanced equation, supposing that exactly
Concept Introduction:
To determine how much product can be formed from a given mixture of reactants, we have to look for the reactant that is limiting; the one that runs out first and thus limits the amount of product that can form. The reactant that runs out first limiting the amount of products form is called the limiting reactant or limiting reagent.
To determine limiting reactant, first we should have a balanced equation. Then we include the information in Before-Change-After table.
E.g
Balanced equation
Before
Change
After
Starting amounts of reactants are presented in before row. The change row represents how much of each substance reacts or is produced. The after row represents how much of each substance remain in the final reaction mixture. The ratio of the numbers in the change row has to be the same as the ratio of the coefficients in the balanced equation.
Answer to Problem 50QAP
The limiting reagent is I2.
Mass of KI produce =
Explanation of Solution
Number of moles of K =
Number of moles of I2 =
Possibility I: if K runs out first
Balanced equation
Before
Change
______________________________________________________
After
Possibility II: if I2 runs out first
Balanced equation
Before
Change
______________________________________________________
After
According to BCA tables, K is not the limiting reactant as, to react with all the K, we need
Mass of KI produce =
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Chapter 9 Solutions
Introductory Chemistry: A Foundation
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