Unit 7 : Stoichiometry

Name:__________ Block:_____

Chemistry 11

Stoichiometry (stoicheion meaning "element" and metron meaning "measure"):

Example: 2 H2(g) + O2(g) → 2 H2O(l)

How does one state the chemical reaction equation above? It turns out that there are actually two ways:

“Two __________________________ of hydrogen react with one ___________________________

of oxygen to produce two __________________________ of water.”

In chemistry we will usually think in terms of _________ rather than ______________.

The mole ratios of coefficients in the balanced reaction equation gives us the mole conversion factors:

Intro to Stoichiometry - Calculating with Chemical Change The reaction between phosphoric acid , H3P04 , and potassium hydroxide , KOH, can produce three different products:

H3P04 + KOH ---+ KH2P04 + H� H3P04 + 2 KOH ---+ K2HP04 + 2 H20 H3P04 + 3 KOH ---+ K3P04 + 3 H�.

Each of the products KH2P04 , K2HP04 and K3P04 , has different properties and different uses.

For example, KH2P04 is used in ________________ , K2HP04 is used in some ________________ and antifreezes , and K3P04 is used in liquid ________________.

The products of this chemical reaction are based on the ____________________________of H3P04 and KOH used.

With stoichiometry, we can predict the amount of a specific product created when a given amount of reactant is used.

EXAMPLE: Consider the reaction equation N 2 + 3 H2 ----+ 2 NH3•

How many molecules of N2 are required to react with 15 molecules of H2?

IMPORTANT: Use completely-labelled units (eg. "molecule N 2'' not just "molecule") so you

know which coefficient goes on top and which goes on the bottom of the conversion factor.

As we have seen earlier, you can convert between the different species in the chemical reaction equation. To do this, however, you must get your substances into _______________: Only moles can cross the mole bridge!

Using the mole bridge, you can convert between any of the following: • a reactant and a product• a reactant and a reactant• a product and a product

Example 1 If 428.5 g of wood were combusted, then what mass of water would be expected to form?

We can use these conversion factors to move from moles of one species to moles of another.

Example Suppose that 1.50 moles of aluminum were produced during a reaction between zinc and aluminum chloride. How many moles of zinc reacted?

The Mole Bridge

Example 2 If 100.0 mL of 1-pentanol were combusted then what volume of CO2 would form, given that the volume would be determined under conditions of STP? (note: d 1-pentanol = 0.881 g/mL)

Example 3 What mass of C3H8 is required to produce 100.0g of H2O?

Basic Stoichiometry Problems

1. What mass of ammonia forms when 5.6 g of nitrogen reacts?N2 + 3H2 - 2NH3

2. What mass of iron must be reacted to produce 32 grams of iron (III) oxide?4Fe + 302 --+ 2Fe2O3

3. What mass of carbon dioxide forms when 1.00 kg of octane is burned?2C8H,8 + 2502 --+ I 6CO

2 + I 8H2O

4. What mass of aluminum is needed to react with 6.4 g of iron (III) oxide?2Al + Fe2O3 - Al2O3 + 2Fe

5. What mass of zinc will react with 50.0 mL of 3.00 M HCI?Zn + 2HCI - ZnCI2 + H2

6. How many mL of 2.00 M HNO3 is needed to consume 5.4 g of aluminum?2AI + 6HNO3 - 2Al(NO3h + 3H2

7. 2Q_ mL of HCI is needed to consume 2.8g Fe. What is the concentration ofHCl?2Fe + 6HC1 --+ 2FeCl3 + 3H2

8. How many mL of 0.80 M AgNO3 will exactly react with l 0.0 mL of 0.25 M AIC13?3AgNO3 + AIC13 --+ 3AgCl + Al(NO3)3

9. 25.0 mL of 0.240M H2SO4 react exactly withy 35.2 mL of KOH. Determine the

concentration of KOH. H2SO4 + 2KOH - K2SO4 + 2H2O

10. How many mL of 0.60M H3PO4 will react with 3Q_ g of Ca(OH)2?2H3PO4 + 3Ca(OH)2 - CaiPO4)2 + 6H2O

l l . What mass of aluminum hydroxide would react exactly with 15.0 rnL of 2.00M HCl?3HC1 + Al(OH)3 - AIC13 + 3H2O

12. What concentration HCI is needed so that 40.Q_ mL will react with 17 .0 g ofmagnesium? Mg + 2HCJ - MgCl2 + H2

13. What mass of copper will react with 10.0 mL of 12.0 M nitric acid?Cu + 4HNO3 - Cu(NO3)i + 2NO2 + 2H2O

14. How many kilograms for oxygen are needed to react with 51 kg of ammonia?4NH3 + 502 - 4NO + 6H2O

Assignment #1: "Basic Stoichiometry Problems" & "Mole Ratio in Reactions"Complete ALL assignments on a separate piece of paper and attach to your booklet when handing in at the end of the unit. Be sure to clearly number each assignment with a heading.

Chap 7: Mole Ratio in Reactions

I. How many moles of 02 are produced from 1.50 moles of KC1O3?

2KC1O3 - 2KC1 + 302

2. How many moles of H2 are needed to react with 8.0 moles of N2?N2 + 3H2 - 2NH3

3. How many moles of HCI are needed to form 4.5 moles of H2?

2Al + 6 HCI - 2AIC13 + 3H2

4. How many moles of water form when 0.50 moles of 02 react?4NH.l + 702 - 4NO2 + 6H2O

5. How many moles of methane can react with 24.0 moles of 02?

CH4 + 202 - CO2 + 2H2O

6. How many moles of calcium phosphate form when 2.0 moles of Ca(OH)2 react?3Ca(OH)2 + 2H3PO4 - CaiPO4)i + 6H2O

7. How many moles of Mg can react with 0.40 mol HCl?Mg + 2HC1 - MgCl

2 + H2

8. How many moles of NaHCO3 must decompose to produce 0.80 mol H2O?2NaHCO3 - Na2O + 2CO2 + H2O

Answers:

1. 2.25 mol2. 24 mol3. 9.0 mo!4. 0.43 mol5. 12.0 mol6. 0.67 mol7. 0.20 mol8. 1.6 mol

Stoichiometry Calculations Involving: Molar Concentration

IMPORTANT: If a VOLUME is mentioned, and the problem involves a molarity, DO NOT assume that "22.4 L" should be used. The use of "22. 4 L" is justified only if the substance being referred to is a gas AND if the key phrase "at STP" is mentioned along with the volume.

Tums™ is an antacid composed primarily of calcium carbonate (chalk), and stomach acid is adilute solution of hydrochloric acid. The neutralization reaction between CaC03 and stomach acid is represented by the equation:

CaC03(s) + 2 HCl(aq) ----> CaCl2(aq) + C02(g) + H2 (I)

a) A tablet of Tums ™ has a mass of 0. 750 g. What volume of stomach acid having[HCI] = 0.0010 M is neutralized by a 0.750 g portion of CaCO3?

Example 1

b) What volume of CO2(g) at STP is produced if 1.25 L of 0.0055 M HCI reacts with anexcess of CaCO3?

A TITRATION is a method used to determine the concentration of an unknown solution.

• How You Do It:

Measure the volume of the solution of known concentration (the known

solution) needed to completely react with a certain volume of the solution

of unknown concentration (the unknown).

• Why It Works:

Consider the following reaction:H2SO4 + 2KOH --> K2SO4 + 2H2O

a) What mass (in g) of water is produced when 125mL of a 0.100M H2SO4 solution is reactedwith excess KOH?

b) What volume of 0.050M KOH solution is needed to completely react with 78mL of 0.28M H2SO4?

Example 2

Titration Reactions

A __________________ is a process in which a _________________________amount of a solution is reacted with known volume of another solution (one of the solutions has an _______________________ concentration) until a desired EQUIVALENCE POINT is reached.

EQUIVALENCE POINT (Stoichiometric Point):

The equivalence point is recognized by an ________________________.

There are many different types of titrations but they all work on the same principle:(In Chemistry 11, we will only look at Acid-Base Reaction Titrations.)

As you combine the solutions, the chemicals react, consuming each other to form products.

1. Until you’ve added enough of reactant A, _______________________________________

2. Once you’ve added just enough to complete the reaction, __________________________

3. Adding more of reactant A (after reaction is over) results in ________________________

The ___________________________________________ is the “point” in the acid-base

titration where all the reactants have been used up (and none are in excess); the number of

moles of each reactant perfectly obeys the stoichiometry (mole ratios) of the reaction equation.

Example 3

When 50.0 mL of HCl were titrated with 0.250 M NaOH, it was determined that 75.0 mL were needed to reach the _______________ point. Determine the [HCl].

Example 4 If 19.8 mL of phosphoric acid reacts completely with 25.0 mL of 0.500 M KOH, then what is the concentration of the phosphoric acid?

Assignment #2: Exercises # 17-23 & Prepare Titration Lab!Complete ALL assignments on a separate piece of paper and attach to your booklet when handing in at the end of the unit. Be sure to clearly number each assignment with a heading.

EXERCISES:

17. A student wants to put 50.0 l of hydrogen gas at STP into a plastic bag by reacting excess aluminummetal with 3. 00 M sodium hydroxide solution according to the reaction

2 Al(s) + 2 NaOH(aq) + 2 H2O(1) _. 2 NaAIO2(aq) + 3 H2(Q).What volume of NaOH solution is required?

18. What volume of 0.250 M HCI is required to completely neutralize 25.0 ml of 0.318 M NaOH? [Hint:what is the balanced equation for the reaction between HCI and NaOH?]

19. A technician analyzes a sample of water from the "tailings" pond of a mine for the presence ofmercury. After treating and concentrating the water sample , the technician carries out the titrationreaction

Hg2+ + 2 c1- � HgCl2(s).A 25.0 ml sample of water containing mercury reacts with 15.4 ml of 0.0148 M c1-(asNaCI).a) What is the molar concentration of the mercury in the water sample?b) What mass of HgCl2 is formed in the reaction?

20. A 1 O. O ml sample of a saturated solution of Ca(OH)2 is titrated with 23. 5 ml of O. 0156 M HCI.a) What is the molarity of the Ca(OH)2 in the saturated solution?b) What mass of Ca(OH)2 is dissolved in 250. O ml of saturated Ca(OH)2?

21. A student titrates a 2. 00 ml sample of hydrogen peroxide solution , H�2(aq), according to thereaction

2 MnO�(aq) +5 H2O2(aq) +6 H+(aq) _. 2 Mn2+(aq) + 5 O2(g) + 8 H2O(1).

The supply bottle of H2O2 is labelled as "3.00% by volume" (3.00 ml of H2O2 per 100 ml of solution),which the student calculates to have [H2O21 = 1. 24 M.a) What volume of o. 0496 M MnO� is required for the titration?b) What volume of 02(9) at STP is produced during the reaction?

22. A 1.00 ml sample of pure phosphoric acid , H3PO4 , is titrated with 43.8 ml of 0.853 M NaOHaccording to the reaction

2 NaOH + H3PO4 _. Na2HPO4 + 2 H2O. a) What is the molar concentration of pure H3PO4?b) Calculate the density of pure H3PO4•

23. The iron present in a sample of iron ore is converted to Fe2+ and titrated with dichromate ionCr20� +6 Fe2+ + 14 H+ _. 2cr3+ +6 Fe3+ + 7 H2O.

If 17.6 ml of 0.125 M dichromate ion is required to titrate a 25.0 ml sample of Fe2+ solution, a) what is the molarity of the Fe2+? b) what mass of iron is present in the 25. o ml sample?

Prepare Acid Base Titration Lab:o flow charto pre-lab questionso set up data tables

Stoichiometry of Limiting & Excess Quantities

2 pieces of bread (Br)4 slices of tomato (To)2 pieces of chicken (Ch)

2Br + 4To + 2Ch --> 1Br2To4Ch2

BUT...what if I had 10 slices of bread, 26 tomatoes and 12 chicken slices?

____ is the limiting reactant (reagent), because we can only make ____ sandwiches, then we are all out of ____________, and have an excess of ______________________________

...Similarly, chemical reactions frequently are carried out in such a way that one or more of the reactants actually are present in ____________ amounts.

Some reasons for having an excess amount:• deliberately adding an excess of 1 reactant to make sure all of a second reactant used (maybe too expensive to

waste, or harmful to the environment)• unavoidably having a reactant in excess because a limited amount of another reactant is available.

ANIMATION: https://phet.colorado.edu/en/simulation/reactants-products-and-leftovers Let's consider an analogy: Suppose I'm making a sandwich. In each sandwich I want:

Consider the simple reaction: 2 Na(s) + Cl2(g) → 2 NaCl(s).

How many moles of Cl2 would you need to use up 2 moles of sodium? Answer: 1 mole.

What would happen if 3.0 moles of sodium and 2.0 moles of chlorine reacted?

Answer: Since 3.0 moles of sodium is only sufficient to react with 1.5 moles of chlorine, all of the sodium will be consumed and 0.50 moles of chlorine will be left in excess.

If 50.0 g Na and 80.5 g Cl2 were reacted?

Answer: You cannot directly compare numbers of atoms by comparing masses. You must convert to

T he reactant that gets used up first is called the limiting reactant because it limits how far the reaction can go. Al l other reactants that are left over after the reaction is finished are called excess reactants.

To use up all 2.17 moles of Na you would need _____ moles of Cl2

moles to compare: moles Na = 50.0 g / 23.0 g/mol = 2.17 mol moles Cl2 = 80.5 g/ 71.0 g/mol = 1.13 moll

You don’t have enough Na to use up the Cl2 (need 2.26 mol Na to use up 1.13 mol Cl2) So ____ is the limiting reactant, ____ mole of ____ reacts, and ____ mole of ____ remains.

How to Determine the Limiting Reactant, Amount of Product(s) and Quantity of Excess Reactant(s):

1. Start by assuming that the first reactant is the limiting reactant (i.e. it gets used up before the others).Calculate how much product it could theoretically produce.

2. Repeat step 1, in turn, for each of the other reactants.

3. Identify the Limiting Reactant (LR) – the one that can make the least amount of product.

Amount of Product Formed = amount of product formed based on amount of LR that reacted 4. Identify the Excess Reactants (XSR) that remain unreacted.

5. Use the LR to find out how much of the other XSR(s)remain. Amount of XSR remaining = XSRinitial – XSRreacted

a) Which of the reactant is in excess?

b) Sketch any remaining reactants and products to show what will be present once the reaction is complete.

c) How many CO2 particles are formed?

d) How many excess reactant particles remain?

2 CO(g) + O2(g) 2 CO2(g)

reactants products

?

Example 1 What volume of hydrogen gas, measured at STP, is produced when 8.0g of lithium metal is reacted with 10.0g of water? What mass of the excess reactant remains once the reaction is completed?

• In limiting and excess problems, you will be given the mass of all of the reactant species and you mustdetermine which of these are in excess...and more importantly, which is the limiting reactant (or reagent) thatlimits the amount of the product that can form.

• You may also have to determine how much of the excess species remains once the reaction is complete.

Example 2 20.0 g of hydrogen react with 100.0 g of oxygen. Identify the limiting reactant and determine the mass of water formed and the mass of the excess reactant.

Example 3 Determine the mass of the excess reactants when 56.8 g of ferrous chloride react with 14.0 g of potassium nitrate and 40.0 g of muriatic acid react as follows:

23 F +e C Kl NO3 + 4 HCl 3 FeCl3 + NO + 2 H2O + KCl

Assignment #3: Exercises # 26-32Complete ALL assignments on a separate piece of paper and attach to your booklet when handing in at the end of the unit. Be sure to clearly number each assignment with a heading.

Calculations of Yield

In any chemical reaction, the amount of product you get is called the chemical yield. The yield always differs

from the amount you expect to form:

Theoretical yield =

Actual yield =

Why does the actual yield differ from the theoretical yield?

There are many possible reasons. Some are acceptable and some aren’t. Here are a few examples: Carelessness or sloppiness. Reactants improperly measured out or lost due to spills, etc. Product left behind in the reaction container when collected or transferred. Products may be contaminated. The mass of the impurity results in greater mass than expected. Note: Water is frequently a source of error. Important to dry samples thoroughly before weighing.

NOTE: we can never make more product than expected (unless we didn't make what we thought we did!)

The ________________of the PRODUCTS should be ________ than the theoretical yield.

3 Types of % Yield Calculations:1. Find the percent yield, given the mass of reactant used and mass of product formed.2. Find the mass of product formed, given the mass of reactant used and the percentage yield.3. Find the mass of the reactant used, given the mass of product formed and the percentage yield.

Example 2 A student carried out an experiment in which she completely reacted 45.8 g of potassium carbonate with an excess of hydrochloric acid. As a result, 46.3 g of potassium chloride were produced. What was the percentage yield of potassium chloride?

________________ + ________________ → ________________ + _____ H2O + _____ CO2

Example 3 When a second student carried out the same reaction as above, 52.7 g of potassium chloride was obtained. Calculate the percentage yield. What most likely explains the result?

If the reaction has a 76.0% yield, what mass of K2CO3(s) is produced when 1.50 g of KO2(s) is reacted with an excess of CO2(g) according to the reaction:

4 KO2(s) + 2 CO2(g) --> 2 K2CO3(s) + 3 O2(g)

Example 4

Sample Purity

When a sample is “impure” it means that only part of its mass is due to the pure substance.

e.g. If sample of NaCl is 75% pure, then 100.0 g of impure sample contains 75.0 g of pure NaCl.

From this equivalence statement, we get the conversion factors:

Example 1 A sample of potassium carbonate is 58.5% pure. What mass of sample contains 87.3 g of potassium carbonate? What mass of potassium carbonate is in 295.3 g of the sample?

x % purity means x grams of ______ ____________ = 100 grams of ________ _________

pure 100.0 impureor

100.0 impure purex g g

g x g

Assignment #4: Exercises # 33-37Complete ALL assignments on a separate piece of paper and attach to your booklet when handing in at the end of the unit. Be sure to clearly number each assignment with a heading.

Chemistry 11 Stoichiometry Review Assignment

Name: ______________________________ Date:______________ Block: _____

Answer the following practice questions on a separate page

Define the following terms:

1. Stoichiometry

2. Stoichiometric ratio

3. Limiting reactant

4. Excess reactant

5. Percent yield

(Mole-Mole Conversions)

6. The combustion of the organic fuel, decane, is outlined in the chemical equation below. You

must balance the equation in order to answer the subsequent questions a-c.

____C10H22 + ____O2 ____CO2 + ____H2O

a. How many moles of CO2 are produced if 5.0 moles of C10H22 react with an

excess of O2?

b. How many moles of O2 react with 0.75 moles of C10H22?

c. How many moles of O2 would be required to produce 4.0 moles of H2O?

7. Use the following equation to solve the problems below:

3 SiO2 + 4 Al 3 Si + 2 Al2O3

a. If 6.0 moles of SiO2 react, how many moles of:

i. Al react?

ii. Si are produced?

iii. Al2O3 are produced?

b. If 2.5 moles of Al2O3 are produced, how many moles of:

i. Al react?

ii. SiO2 react?

b) If 4.0x10-3 moles of oxygen reacted, how many grams of N2 were needed?

9. Cu + 2AgNO3 → Cu(NO3)2 + 2Ag How many moles of Cu are needed to react with 3.50g of

AgNO3?

10. Mercury (II) oxide decomposes into mercury and oxygen gas.

a) Write and balance the equation.

b) How many moles of mercury (II) oxide are needed to produce 125g of oxygen?

c) How many grams of mercury are produced if 24.5 moles of mercury (II) oxide decomposes?

(Mass-Mass Conversions)

11. Li3N(s) + 3H2O(l) → NH3(g) + 3LiOH(aq)

a. What mass of lithium hydroxide are produced when 0.38g of lithium nitride react?

b. How many grams of lithium nitride would react with 4.05g of H2O?

12. In the combustion of 54.50g of butane (C4H6), how many grams of CO2 are produced? Write and

balance the equation before solving.

13. In the following unbalanced equation,

___ FeS2 + ___O2 → ___Fe2O3 + ___SO2

a. How many grams of iron (IV) sulphide are used when 9.0g of O2 react?

b. What is the mass of iron (III) oxide produced when 25.0g of iron (IV) sulphide are used?

14. Cu + 2AgNO3 → 2Ag + Cu(NO3)2

How many grams of silver are produced when 36.92g of copper react?

15. ___Al2(SO4)3 + ___Ca(OH)2 →___Al(OH)3 + ___CaSO4

Balance and answer the following questions.

a. What mass of aluminum (III) hydroxide are produced if 165.7g of aluminum (III) sulfate

react?

b. How many grams of calcium hydroxide are needed to form 6.35g of calcium sulphate?

(Mole-Mass / Mass-Mole Conversions)

8. N2 + 2O2 → N2O4

a) If 15.0g of N2O4 was produced, how many moles of O2 were required?

a. What mass of water is required to react with 15.5 L of Nitrogen dioxide?

b. What volume of Nitrogen monoxide would be produced from 100.0 g of water?

c. If 42.0 L of NO(g) is produced, what volume of NO2 (g) reacted?

17. When Magnesium reacts with Nitric Acid, Hydrogen gas and aqueous Magnesium nitrate are

formed. What volume of Hydrogen gas will be produced if 40.0 g of Magnesium is reacted with

an excess of Nitric Acid?

18. The corrosion (rusting) of iron is represented as follows: (at STP)

3 O2 (g) + 4 Fe(s) 2 Fe2O3 (s)

a. What volume of Oxygen gas would be required to produce 16.0 g of Fe2O3?

b. What mass of Iron would be required to react with 10.0 L of O2 gas?

19. Mercury (II) oxide decomposes when heated to produce liquid Mercury and Oxygen gas. What

mass of Mercury (II) oxide would be required to produce 30.5 L of Oxygen gas? (Assume STP)

20. How many mL of 2.00M HNO3 is needed to consume 5.4g of aluminum?

2Al + 6HNO3 2Al(HNO3)3 + 3H2

21. 20mL of HCl is needed to consume 2.8g Fe. What is the concentration of HCl?

__Fe + __HCl __FeCl3 + __H2

22. What mass of copper will react with 10.0mL of 12.0M nitric acid?

Cu + __HNO3 __Cu(NO3)2 + __NO2 + __H2O

(Mass- Volume/ Volume-Volume Conversions)

16. Given the following equation:

3 NO2 (g) + H2O(l) 2 HNO3 (aq) + NO(g) Assume STP

REVIEW: Limiting Reagents and Percent Yield

Answer all questions on separate paper and report all answers to the correct number of sig�figs.

1. Identify the limiting reactant when 1.22g of O2 reacts with 1.05g of H2 to produce water.

2. Identify the limiting reactant when5.87g of Mg(OH)2 reacts with 12.84g of HCl to form

MgCl2 and water.

3. Identify the limiting reactant when 6.33g of sulphuric acid reacts with 5.92g of sodium

hydroxide to produce sodium sulphate and water.

4. Identify the reactant in excess if 6.25g of silver nitrate reacts with 4.12g of sodium

chloride to form sodium nitrate and silver chloride.

5. If 4.1g of Cr is heated with 9.3g of Cl2 what mass of CrCl3 will be produced?

6. What mass of sulphur trioxide is produced when 12.4g of sulphur dioxide is reacted with

3.45g of oxygen gas?

7. If 21.4g of aluminum is reacted with 91.3g of iron (III) oxide, the products will be

aluminum oxide and iron. What mass of iron will be produced?

8. If 41.6g of N2O4 reacts with 20.8g of N2H4, the products will be nitrogen gas and water.

What mass of nitrogen will be produced?

9. What mass of NaCl will be produced by the reaction of 58.7g of NaI with 29.4g of Cl2?

10. a. Write the balanced equation for the reaction of lead (II) nitrate with sodium iodide to

form sodium nitrate and lead (II) iodide:

b. If I start with 25.0 grams of lead (II) nitrate and 15.0 grams of sodium iodide, how

many grams of sodium nitrate can be formed?

c. What is the limiting reagent in the reaction?

d. How much of the excess reagent will be left over from the reaction?

11. You calculate that using a certain amount of beryllium and hydrochloric acid you can

produce 10.7g of beryllium chloride. You perform the experiment and only collect 4.5g.

What was the percent yield for the reaction?

12. Determine the percent yield for the reaction between 45.9g of NaBr and excess chlorine

gas to produce 12.8g of NaCl and an unknown quantity of bromine gas.

13. Determine the percent yield for the reaction between 44.5g of zinc sulphide and 13.3g of

oxygen, if 18.4g of zinc oxide is recovered with an unknown amount of sulphur dioxide.

14. A reaction was carried out according to the following equation:

FeBr2 + 2 KCl � FeCl2 + 2 KBr

a. What is the theoretical yield of iron (II) chloride if 34.00 grams of iron (II) bromide

was used in the reaction with excess potassium chloride?

b. What is the percent yield of iron (II) chloride if the actual yield is 4.00 grams?

15. a. What mass of CS2(s) is produced when 17.5 g of C(s) are reacted with 39.5 g of SO2(g)

according to the equation: 5 C(s) + 2 SO2(g) → CS2(s) + 4 CO(g)?

b. What mass of the excess reactant will be left over?

16. If 0.250 g of Ba(OH)2(s) is mixed with 15.0 mL of 0.125 M HBr(aq), what mass of

BaBr2(aq) can be formed?

Ba(OH)2(s) + 2 HBr(aq) → BaBr2(aq) + 2 H2O(l)

17. The reaction SiO2(s) + 4 HF(g) → SiF4(g) + 2 H2O(g) produces 2.50 g of H2O(g) when

12.20g of SiO2(s) is treated with a small excess of HF(g).

a. What mass of SiF4(g) is formed?

b. What mass of SiO2(s) is left unreacted if only 2.50g of H2O is formed?

c. What is the percent yield of the H2O(g)?