Chapter 04 Chemical Reactions and Chemical Quantities Dynamic Study Module
Stoichiometry is a term chemists use to describe calculations that determine the relative quantities of reactants or products involved in a chemical reaction.
Using stoichiometry, chemists can determine the amount of product that can be formed during a chemical reaction from a given amount of reactant. Chemists can also determine the amount of reactant needed to produce a desired amount of product using the same process.
Select the missing conversion factor for the following set of calculations.
Assume 95.4 grams of zinc, Zn, reacts with hydrochloric acid, HCl, to produce zinc chloride, ZnCl 2 , and hydrogen, H 2 . The problem requires that you determine the mass of hydrochloric acid, HCl, needed for the reaction to occur.
Zn( s ) + 2 HCl( aq ) → ZnCl 2 ( aq ) + H 2 ( g )
Stoichiometry is a term chemists use to describe calculations that determine the relative quantities of reactants or products involved in a chemical reaction.
Using stoichiometry, chemists can determine the amount of product that can be formed during a chemical reaction from a given amount of reactant. Chemists can also determine the amount of reactant needed to produce a desired amount of product using the same process.
What mass of AgCl will precipitate when 10.0 g of AgNO 3 is added to an aqueous solution of NaCl?
NaCl( aq ) + AgNO 3 ( aq ) → AgCl( s ) + NaNO 3 ( aq )
8.44 g AgCl
Ex.
The addition of 10.0 grams of AgNO 3 will result in the precipitation of 8.44 grams of AgCl .
Use the molar masses and the mole ratio from the coefficients of the balanced chemical equation to calculate the mass of AgCl produced.
The limiting reactant is the chemical substance that determines the amount of product(s) that can ultimately be formed in a reaction. During the reaction, the limiting reactant is completely consumed or used up, and therefore, causes the reaction to stop.
The limiting reactant can be identified through stoichiometric calculations. After comparing the results, the reactant that produces the smaller mass of product is identified as the limiting reactant.
Determine the excess reactant and calculate the mass of the remaining excess reactant after 7.50 grams of Fe and 5.00 grams of O 2 react.
4 Fe( s ) + 3 O 2 ( g ) → 2 Fe 2 O 3 ( s )
Excess reactant: O 2
Grams remaining: 1.78 g of O 2
Ex.
The excess reactant is O 2, and 1.78 grams of O 2 remain after the reaction.
From the calculations, the smaller amount of product is the 10.7 g of Fe 2 O 3 . Therefore, Fe is the limiting reactant and O 2 is the excess reactant.
Use the amount of limiting reactant (7.50 g Fe) to determine the amount of O 2 needed.
Subtract the amount needed from the amount given to determine the excess.
A balanced chemical equation indicates the proportions or ratios of the various reactants and products to one another. From the coefficients in the balanced chemical equation, we can create mole–mole ratios that relate any of the various chemicals to a different chemical.
For example, consider the following balanced chemical equation:
N 2 ( g ) + 3 H 2 ( g ) → 2 NH 3 ( g )
From this equation, there are several possible mole–mole ratios. Two of these mole–mole ratios are the following:
3 moles H2 / 1 mole N2
OR
2 moles NH3 / 3 moles H2
Which is a possible mole-mole ratio for the following balanced chemical equation?
Mg(OH) 2 ( s ) + 2 HCl( aq ) → 2 H 2 O( l ) + MgCl 2 ( aq )
The limiting reactant is the chemical substance that determines the amount of product(s) that can ultimately be formed in a reaction. During the reaction, the limiting reactant is completely consumed or used up and therefore causes the reaction to stop.
The limiting reactant can be identified through stoichiometric calculations. After comparing the results, the reactant that produces the smaller mass of product is identified as the limiting reactant.
You are going to have a surprise birthday party for your friend, and you are going to mail out the invitations. Each invitation needs one envelope, two stamps, one address label, two RSVP cards, and one invitation. What is your limiting reactant if you have the following materials?
7 envelopes
16 stamps
30 address labels
20 RSVP cards
10 invitations
Stoichiometry is a term chemists use to describe calculations that determine the relative quantities of reactants or products involved in a chemical reaction.
Using stoichiometry, chemists can determine the amount of product that can be formed during a chemical reaction from a given amount of reactant. Chemists can also determine the amount of reactant needed to produce a desired amount of product using the same process.
Select the missing conversion factor for the following set of calculations.
Assume 94 grams of calcium cyanamide, CaCN 2 , reacts with water, H 2 O, to produce calcium carbonate, CaCO 3 , and ammonia, NH 3 . The problem requires that you determine the mass of water, H 2 O, needed for the reaction to occur.
CaCN 2 ( s ) + 3 H 2 O( l ) → CaCO 3 ( s ) + 2 NH 3 ( g )
A combustion reaction occurs when a fuel source reacts with oxygen (O 2 ) to form carbon dioxide (CO 2 ) and water (H 2 O). Combustion reactions are frequently thought of as burning a fuel source. The fuel source is typically made of carbon and hydrogen or carbon, hydrogen, and oxygen.
What is the missing equation coefficient that belongs in front of oxygen (O 2 ) in the combustion reaction for methane, CH 4 ?
CH 4 ( g ) + _ O 2 ( g ) → CO 2 ( g ) + 2 H 2 O( g )
In order to balance a reaction, the same number and type of atoms must exist on both sides of an equation. Begin by counting the number of atoms on the reactant side, and confirm that the product side has the same number of atoms. If there is a discrepancy in the number of atoms, change the equation coefficient or the number in front of the chemical formula until both sides of the equation have the same number of atoms.
What is the missing equation coefficient that belongs in front of iron (Fe) in the reaction shown below?
Fe 2 S 3 ( l ) → _ Fe( s ) + 3 S( s )
The limiting reactant is the chemical substance that determines the amount of product(s) that can ultimately be formed in a reaction. During the reaction, the limiting reactant is completely consumed or used up and therefore causes the reaction to stop.
The limiting reactant can be identified through stoichiometric calculations. After comparing the results, the reactant that produces the smaller mass of product is identified as the limiting reactant.
Determine the limiting reactant and calculate the number of grams of Al 2 O 3 that can be formed when 10.0 grams of Al and 5.00 grams of O 2 react.
4 Al( s ) + 3 O 2 ( g ) → 2 Al 2 O 3 ( s )
Limiting reactant: 5.00 g of O 2
Grams of formed: 10.6 g of Al 2 O 3
Stoichiometry is a term chemists use to describe calculations that determine the relative quantities of reactants or products involved in a chemical reaction.
Using stoichiometry, chemists can determine the amount of product that can be formed during a chemical reaction from a given amount of reactant. Chemists can also determine the amount of reactant needed to produce a desired amount of product using the same process.
What mass of CO 2 is produced from the decomposition of 25.5 grams of NaHCO 3 ?
NaHCO 3 ( aq ) → NaOH( aq ) + CO 2 ( g )
13.4 g CO 2