Limiting Reactant Activity - Mrs. Kline's Webpage



Chemistry HonorsName ___________________________________The Nuts & Bolts of Chemical ChangesPre-LabMethane gas reacts with oxygen gas to produce carbon dioxide and water vapor. The chemical equation is:CH4 + O2 H2O + CO2a) Balance this chemical equation.b) How many moles of oxygen gas are needed to react with 5 moles of methane (CH4)?c) What would happen if you used twice as many moles of oxygen gas as you calculated in b) and still had 5 moles of methane to react with? In this activity we will use nuts and bolts to represent atoms in involved in a chemical change.1) Obtain one of the numbered sets of nuts and bolts from your instructor. Record the number of your set.Set # __________2) Count the number of bolts and nuts. Record these numbers.# Bolts _________# Nuts ___________3) Now put as many nuts as you can completely fit on each bolt in your set. The nuts must completely fit on the bolt, none of the nut should be hanging off the bolt.Which did you not have enough of to combine, nuts or bolts?In chemical reactions atoms combine in specific numbers. In the nuts and bolts example above the bolts would only hold two nuts for each bolt. Atoms behave this way also; they have a specific combining capacity (valence) when they make a compound with other atoms.In chemical changes, the reactant that is left over and doesn’t have anything to combine with is called the excess reactant, and the reactant that is completely combined is called the limiting reactant.4) A) What was the excess reactant (nuts or bolts) in your set?B) What was the limiting reactant (nuts or bolts) in your set?C) Define the terms limiting reactant and excess reactant in your own words.5) Take an inventory of your nut and bolt combinations:A) How many bolt/nut combinations were you able to make with your set? ________bolt/nut combinationsB) How many total bolts did it take to make all your nut/bolt combinations? _________ boltsC) How many total nuts did it take to make all your nut/bolt combinations? __________ nuts6) A) For each of the following sets of nuts and bolts state: the number of bolt/nut combinations and how many nuts or bolts are left-over. Use the combining pattern you observed with your set.i) 12 bolts and 12 nutsbolt/nut combinations____________left-over bolts____________left-over nuts____________ii) 100 bolts and 223 nutsbolt/nut combinations____________left-over bolts____________left-over nuts____________iii) 73 bolts and 146 nutsbolt/nut combinations____________left-over bolts____________left-over nuts____________B) For each of the combinations above in 6A, state whether bolts or nuts represents the limiting reactant.i)limiting reactant___________ii)limiting reactant___________iii)limiting reactant___________C) Using the symbol B to represent bolt and N to represent nut, write a “chemical equation” to represent the simplest way bolts combined with nuts. In other words, all your classmates were given different numbers of the SAME type of nut and bolt; write a chemical equation that would represent what happens in EVERY set when nuts and bolts are combined.7) The diagram below, the left circle represents gaseous carbon and sulfur before they react; the diagram on the right represents the compound that results when these atoms combine.BEFORE REACTIONAFTER REACTIONCCCCCCSSSSCSSCSSCCCCA) Take an inventory. Count the particles in each diagram and list them in the table below. Before Reaction After Reaction___________ C atoms___________ CS2 molecules___________ S atoms___________ C atomsB) Which reactant (C or S atoms) is in excess?_____________C) Which reactant (C or S atoms) limits the reaction?_____________When writing an equation to represent this chemical change, remember, the equation shows how carbon would combine with sulfur no matter how many total atoms you start with, or what is leftover (in excess). Just as you did with the nuts and bolts combination, we want a general statement that tells us how carbon combines with sulfur.D) Write a chemical equation to represent how carbon atoms react with sulfur atoms.8) In the chemical equation below:2Na + S Na2SWhat is the difference between using 2 as a coefficient (e.g. 2Na) and using it as a subscript (e.g. Na2S)?9) The diagram below represents the chemical reaction between nitrogen gas and hydrogen gas.=hydrogen atom atom=nitrogen atomA) What is the limiting reactant in this chemical change?_________________B) What is the excess reactant in this chemical change?_________________C) Write a chemical equation to represent this reaction.10) The diagram below represents the chemical reaction between krypton gas and fluorine gas.= Kr= FA) What is the limiting reactant in this chemical change?_____________B) What is the excess reactant in this chemical change?_____________C) Write a chemical equation to represent this reaction.11) The diagram below represents the chemical reaction between fluorine and iodine gas. A) What is the limiting reactant in this chemical change?______________B) What is the excess reactant in this chemical change?______________C) Write a chemical equation to represent this reaction.12) The diagram below shows the chemical reaction between sulfur tetrafluoride and fluorine gas.= F= SA) What is the limiting reactant in this chemical change?______________B) What is the excess reactant in this chemical change?______________C) Write a chemical equation to represent this reaction.13) The diagram below shows the chemical reaction between ethyne gas and oxygen gas.= O= C= HA) What is the limiting reactant in this chemical change?______________B) What is the excess reactant in this chemical change?______________C) Write a chemical equation to represent this reaction.14) Carbon monoxide gas reacts with oxygen gas to produce carbon dioxide gas. The balanced chemical equation is:2CO + O2 2CO2A) In the diagram below draw what you would expect to see in the right circle after this chemical reaction has occurred.= C= OB) What is the limiting reactant in this chemical change?______________C) What is the excess reactant in this chemical change?______________15) Sulfur dioxide gas reacts with oxygen gas to produce sulfur trioxide gas. The balanced chemical equation is:2SO2 + O2 2SO3A) In the diagram below draw what you would expect to see in the right square after this chemical reaction has occurredB) What is the limiting reactant in this chemical change?______________C) What is the excess reactant in this chemical change?______________16) Hydrogen gas and chlorine gas react to produce hydrogen monochloride gas. The balanced chemical equation is:H2 + Cl2 2HClA) In the diagram below draw what you would expect to see in the right circle after this chemical reaction has occurred.HHHHHHHHClClClClB) What is the limiting reactant in this chemical change?______________C) What is the excess reactant in this chemical change?______________17) Fluorine gas and water vapor react to produce oxygen difluoride gas and hydrogen monofluoride gas. The balanced chemical equation is :2F2 + H2O OF2 + 2HFA) In the diagram below draw what you would expect to see in the right circle after this chemical reaction has occurred.HHHHHHHHFFFFFFOOOOFFB) What is the limiting reactant in this chemical change?______________C) What is the excess reactant in this chemical change?______________18) Under high pressure and temperature xenon gas will react with oxygen gas to produce xenon trioxide. The balanced chemical equation is:2Xe + 3O2 2XeO3A) In the diagram below draw what you would expect to see in the right circle after this chemical reaction has occurred.= O= XeB) What is the limiting reactant in this chemical change?______________C) What is the excess reactant in this chemical change?______________19) Chlorine gas will react with fluorine gas to produce chlorine pentafluoride gas. The balanced chemical equation is:Cl2 + 5F2 2ClF5A) Draw what you would expect to see in the circle on the right at the completion of the reaction described above.= F= ClB) What is the limiting reactant in this chemical change?______________C) What is the excess reactant in this chemical change?______________ ................
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