Blog Archives

Predicting products of a combustion reaction (5th type)

11/25/2014

This brief post is focused on a 5th type of chemical reaction, Combustion of a Hydrocarbon. November’s end of month blog posts focus on five types of chemical reactions, Synthesis, Decomposition, Single Replacement, Double Replacement, and Combustion of a Hydrocarbon.

Objectives:

1. Predict the products of the Combustion of a Hydrocarbon reaction.

2. Balance a chemical equation.

This type of chemical reaction was also discussed on 01/22/2014 in a blog post titled “Combustion of a Hydrocarbon”.

In a Combustion of a Hydrocarbon Reaction, a hydrocarbon reacts with oxygen to form water and carbon dioxide. For the introductory chemistry student, I am focusing on simple hydrocarbons (alkanes, alkenes and alkynes).

This is easily observed in the combustion of methane gas in the Bunsen burner.

One lab possibility is:

http://chemsite.lsrhs.net/AtomicTheory/Handouts/Bunsen_Intro.pdf

*My 01/22/2014 blog post discusses balancing of Combustion of a Hydrocarbon reaction. I recommend that you check it out!

Here is a worksheet on Combustion of a Hydrocarbon reactions w/ answers:

http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet6.pdf

This is my last November post before Thanksgiving (11/27)!

Check out the Topic List to help you to find past Blog entries. I hope it helps!

The holidays approach, so buy my lab book "Chemistry on a Budget" (or ask for it as a gift) -- it is available for $20 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Have a good Thanksgiving!

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Predicting Products of a double replacement reaction (4th type of rxn)

11/23/2014

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This brief post is focused on a 4th type of chemical reaction, Double Replacement. November’s end of month blog posts focus on five types of chemical reactions, Synthesis, Decomposition, Single Replacement, Double Replacement, and Combustion of a Hydrocarbon.

Objectives:

1. Predict the products of a Double Replacement reaction.

2. Determine if a double replacement reaction will occur based on the products of the reaction and the Solubility Rules.

3. Balance a chemical equation.

This type of chemical reaction was also discussed on 01/18/2014 in a blog post titled “Double Replacement Reactions”.

In a Double Replacement Reaction (or double displacement), two compounds react to form two new compounds. The reaction of two aqueous solutions is typical at the introductory level.

For the reaction to occur, a product must leave the system and not stay as ions dissolved in solution. A solid, insoluble product known as a precipitate must be formed, or a pure liquid, or a gas which would leave the system.

A downward arrow is used to indicate a precipitate and an upward arrow is used to indicate gas formation.

The Solubility Rules aid in predicting the precipitate in a reaction.

Here is one chart:

http://pmstechnoreview.weebly.com/uploads/1/2/5/0/12509397/831158990.jpg

Check in your chemistry department to see what is traditionally completed for this topic. Don’t reinvent the wheel!

Here’s a lab reacting six different solutions to provide 15 different reaction combinations to observe.

https://c7chemistry.wikispaces.com/file/view/CW+double+replacement+lab+120110.pdf

I have performed these type of reactions in spot plates, but also with a half sheet of plastic overhead place on top of the table. It can be easily slid away to write down notes or observe the solution on the black lab tabletop. Then the plastic sheet can be slid back into place.

Here is another lab – your students could provide their own data charts:

http://sharepoint.mvla.net/teachers/DarrenD/Chemistry/Lists/Chem%20Calendar/Attachments/143/Double%20Replacement%20Procedure-Data.pdf

Here is a worksheet on Double Replacement reactions w/ answers:

http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet5.pdf

You may have to aid your students with some chemical formulas.

I will try to have one more short post before Thanksgiving (11/27)!

Check out the Topic List to help you to find past Blog entries. I hope it helps!

The holidays approach, so buy my lab book "Chemistry on a Budget" (or ask for it as a gift) -- it is available for $20 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Have a good week!

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predicting products of a single replacement reaction (3rd type)

11/21/2014

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This brief post is focused on a 3rd type of chemical reaction, Single Replacement. November’s end of month blog posts focus on five types of chemical reactions, Synthesis, Decomposition, Single Replacement, Double Replacement, and Combustion of a Hydrocarbon.

Objectives:

1. Predict the products of a Single Replacement reaction.

2. Use a chemical Activity Series to determine if a chemical reaction will occur.

3. Balance a chemical equation.

This type of chemical reaction was also discussed briefly in the 01/11/2014 blog post titled “New Schedule".

In a Single Replacement Reaction an element and a compound react to form another element and compound. The Activity Series indicates what elements are more active to replace an element and take its place in a compound.

Here is a webpage showing one example:
http://www.grandinetti.org/activity-series

Elements higher on the list will replace elements lower on the list. This list is a collection of the observations over years.

For example, copper is higher on the list than silver, so will exchange places as shown in the 01/11/2014 blog post.

The reaction is:

Cu (s) + AgNO3 (aq) --> Ag (s) + CuNO3 (aq)

Another example is zinc metal with hydrochloric acid producing hydrogen gas and zinc chloride:

Zn (s) + HCl (aq) à H2 (g) + ZnCl2 (aq)

The balanced reaction is:

Zn (s) + 2 HCl (aq) à H2 (g) + ZnCl2 (aq)

Here’s a demonstration using a balloon to capture the gas:

The zinc metal is placed in the balloon and 3M or 6M hydrochloric acid is placed in the Erlenmeyer flask.

Here is a worksheet on Single Replacement reactions w/ answers:

http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet4.pdf

You may have to aid your students with some chemical formulas.

I will try to have two more short posts through the end of the month of November to address the other types of reactions. I hope to have this done before Thanksgiving (11/27)!

Check out the Topic List to help you to find past Blog entries. I hope it helps!

The holidays approach -- you can purchase my lab book "Chemistry on a Budget" (or ask for it as a gift) -- it is available for $20 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Have a good weekend!

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predicting products of a decomposition reaction (2nd rxn type)

11/17/2014

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This brief post is focused on a 2nd type of chemical reaction, Decomposition. November’s end of month Blog post focus on five types of chemical reactions, Synthesis, Decomposition, Single Replacement, Double Replacement, and Combustion of a Hydrocarbon.

Objectives:

1. Predict the products of a Decomposition reaction.

2. Balance a chemical equation.

3. Identify the seven diatomic elements.

This type of chemical reaction was also discussed in the 01/14/2014 blog post about the "Decomposition of Sodium Bicarbonate".

Predicting Products of chemical reactions uses the skill of Formula Writing, knowledge of the Diatomic Elements, and the skill of Balancing Equations to produce a final reaction.

In a Decomposition Reaction a single compound is broken down to two or more chemicals.

For an introductory chemistry student, I am focusing on the reaction of one compound to produce two elements.

However, an easy reaction to perform in the classroom is the decomposition of hydrogen peroxide (H2O2) using yeast as a catalyst to produce oxygen gas.

2 H2O2 (aq) à 2 H2O (l) + O2 (g)

Other catalysts can be used to decompose the hydrogen peroxide, but yeast is easy to obtain at the local grocery store.

A wooden splint that has been lit then blown out produces a glowing splint – it will relight when place into a container with pure oxygen gas. A test tube held over the reaction container (another test tube concentrates the gas) can collect the gas easily.

This could be performed by students (wearing goggles of course!) and is a very exciting lab experience. A student will feel like a magician! And the glowing splint can be relit several times in the container of oxygen.

Here is a brief video showing the decomposition of hydrogen peroxide with potassium iodide – with soap to produce a foam:

Here is another video showing how to prepare this demonstration:

This reaction is sometimes known as “elephant’s toothpaste” and is described here using yeast as the catalyst:
http://www.stevespanglerscience.com/lab/experiments/elephants-toothpaste

Here’s a video performing this reaction with yeast:

I previously posted about diatomic molecules and balancing reactions, but I include this just in case you missed it.

This reaction produces oxygen gas in an elemental state where the element is more stable bonded to itself, producing a diatomic molecule. There are seven elements found in a diatomic state – they are bromine, iodine, nitrogen, chlorine, hydrogen, oxygen, and fluorine. An easy pneumonic to remember this is “BrINClHOF” (pronounced “brin-cl-hoff).

Chemistry is the study of Matter and Energy and the changes they undergo. The Laws of Thermodynamics provide the parameters in which reactions will occur. The 1st Law of Thermodynamics states that matter and energy can neither be created nor destroyed but can only change forms.

To follow this 1st law of Thermodynamics, the number of atoms reacting (on the left side of the arrow of a reaction) must be the same as the number of atoms produced (on the right side of the arrow of a reaction).

In this reaction H2O2 (aq) à H2O (l) + O2 (g), there is 1 molecule of H2O2 composed of 2 atoms of hydrogen and 2 atoms of oxygen decomposing to produce 2 atoms of hydrogen and 1 atom of oxygen (in the H2O molecule) and 2 atoms of oxygen in a diatomic molecule. This reaction does not follow this 1st Law of Thermodynamics because it is not balanced.

To balance a chemical reaction, a chemist can only place numbers in front of a correctly written symbol or formula. Subscripts are not added to balance a reaction.

These numbers in front of a formula are called “coefficients” and The number “1” is never written out as a coefficient. If the formula is written without a coefficient there is one unit of that formula.

The final balanced reaction is:

2 H2O2 (aq) à 2 H2O (l) + O2 (g)

Here is a worksheet on Decomposition reactions w/ answers:

http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet3.pdf You may have to aid your students with some chemical formulas.

I will post 3 more short posts through the end of the month of November to address the other types of reactions. I hope to have this done before Thanksgiving (11/27)!

Check out the Topic List to help you to find past Blog entries. I hope it helps!

The holidays approach, so buy my lab book "Chemistry on a Budget" (or ask for it as a gift) -- it is available for $20 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Have a good week!

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predicting products of a synthesis reaction (1st rxn type)

11/14/2014

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Today, I am going to focus on the most basic of beginning chemical reactions as well as the beginnings of Balancing Chemical Reactions.

I am going to post this blog five times by the end of November (my goal being before Thanksgiving) to address five types of chemical reactions, Synthesis, Decomposition, Single Replacement, Double Replacement, and Combustion of a Hydrocarbon.

Objectives:

1. Predict the products of a Synthesis (or Combination) reaction.

2. Balance a chemical equation.

3. Identify the seven diatomic elements.

This type of chemical reaction was also discussed in the 01/16/2014 blog post about the "Combination of Magnesium & Oxygen" .

Predicting Products of chemical reactions uses the skill of Formula Writing, knowledge of the Diatomic Elements, and the skill of Balancing Equations to produce a final reaction.

A Synthesis Reaction (or Combination) is the chemical combination of one or more chemicals to produce one compound.

For an introductory chemistry student, I am focusing on the reaction of two elements to form one compound.

The brief video shown here is the reaction of iron with sulfur to form iron sulfide:

This is a simple reaction to write and balance:

Fe (s) + S (s) à FeS (s) + energy

It is an exothermic reaction so this concept can be discussed as well.

This reaction is easy to perform on top of wire gauze -- the wire gauze will be difficult to clean and may have to be thrown out after. This is also a smelly reaction producing iron oxide which smells like rotten eggs.

Fe (s) + O2 (g) à FeO (g)

This reaction shows oxygen gas in an elemental state where the element is more stable bonded to itself producing a diatomic molecule. There are seven elements found in a diatomic state – they are bromine, iodine, nitrogen, chlorine, hydrogen, oxygen, and fluorine. An easy pneumonic to remember this is “BrINClHOF” . (sounds like brinclhoff)

Chemistry is the study of Matter and Energy and the changes they undergo. The Laws of Thermodynamics provide the parameters in which reactions will occur. The 1st Law of Thermodynamics states that matter and energy can neither be created nor destroyed but can only change forms.

To follow this 1st law of Thermodynamics, the number of atoms reacting (on the left side of the arrow of a reaction) must be the same as the number of atoms produced (on the right side of the arrow of a reaction).

In this reaction Fe (s) + O2 (g) à FeO , there is 1 atom of Fe and 2 atoms of oxygen reacting and 1 atom of iron and only 1 atom of oxygen produced. This reaction does not follow this 1st Law of Thermodynamics because it is not balanced.

To balance a chemical reaction, a chemist can only place numbers in front of a correctly written symbol or formula. Subscripts are not added to balance a reaction.

These numbers in front of a formula are called Coefficients and the number “1” is never written out as a coefficient. If the formula is written without a coefficient, there is one unit of that formula.

I’m sort of old-fashioned when it comes to balancing reactions, simply comparing reactants and products until it’s balanced, and I will offer some “tricks” along the way.

Here is one worksheet that focuses on Synthesis reactions and requires prediction of products (formula writing) and balancing of reactions. It also has the answers:

http://www.sciencegeek.net/Chemistry/chempdfs/EquationsWorksheet2.pdf

I will post 4 shorter posts through the end of the month of November to address the other types of reactions. I hope to have this done before Thanksgiving (11/27)!

Check out the Topic List to help you to find past Blog entries.

As the holidays approach, buy my lab book "Chemistry on a Budget" (or ask for it as a gift) -- it is available for $20 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Have a good weekend!

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Molar volume of a gas

11/7/2014

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In reviewing my blog, I noticed that my posts about the Mole have been a little scattered. FYI, they include:

1/10/14            2nd entry (which includes a Moletown map)

10/20/14          Celebrating Mole Day

10/23/14          Mole Labs in My Book

A pretty common lab at the introductory level is the generation of hydrogen gas by reacting magnesium metal (most likely in ribbon form in your department) with hydrochloric acid.  The reaction is as follows:

                                       Mg (s)   + 2 HCl (aq) ---> MgCl2 (aq) + H2 (g)

Here is a brief demonstration of this method of generating hydrogen gas:

Remember to wear goggles during the lab and cleanup! I have completed this lab with a one-hole stopper where the copper wire was inserted through the stopper. DO NOT use a solid stopper because the gas pressure could build up, a dangerous high pressure system.

Here are a few lab handouts for the Molar Volume of a Gas using magnesium and hydrochloric acid. Most of the labs are more than 2 pages -- it's difficult to find a shorter version of this lab:

http://www.gru.edu/colleges/scimath/chemistryandphysics/documents/molarvolumeofgas.pdf

https://www.asdk12.org/staff/roach_heather/HOMEWORK/120145_Molar_Volume_of_Gas_Lab.pdf

This handout contains a table of water's vapor pressure at various temperatures:
https://sp.eths.k12.il.us/weinerj/2chemphys/UNIT%20FILES/Unit%207%20%20Kinetic%20Theory%20and%20Gases/LAB%20EXPERIMENTAL%20DETERMINATION%20OF%20THE%20MOLAR%20VOLUME%20OF%20A%20GAS%20revised.pdf

Although several pages, this is a good overview with a data table:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=50&ved=0CFIQFjAJOCg&url=http%3A%2F%2Fwww.smusd.org%2Fsite%2Fhandlers%2Ffiledownload.ashx%3Fmoduleinstanceid%3D4199%26dataid%3D8288%26FileName%3DThe%2520Gas%2520Laws%2520Lab%25202014.pdf&ei=kcZbVNqCOsGqoQTEpYLoDg&usg=AFQjCNHxmnl5x5oglTpa9NyYHWtH_DZhzA

This Flinn Scientific handout is long, but it could be a useful reference for the teacher:
http://www.flinnsci.com/media/960405/ap_chem_3A.pdf

Check out the Topic List to help you to find past Blog entries. I hope it helps!

Buy my lab book "Chemistry on a Budget" -- it is available for $20 at amazon.com or $23 at lulu.com:

http://www.amazon.com/Chemistry-Budget-Marjorie-R-Heesemann/dp/0578129159/ref=sr_1_1?s=books&ie=UTF8&qid=1389410170&sr=1-1&keywords=chemistry+on+a+budget

http://www.lulu.com/shop/marjorie-r-heesemann/chemistry-on-a-budget/paperback/product-21217600.html

This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.

Have a good weekend!

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Predicting products of a combustion reaction (5th type)

Predicting Products of a double replacement reaction (4th type of rxn)

predicting products of a single replacement reaction (3rd type)

predicting products of a decomposition reaction (2nd rxn type)

predicting products of a synthesis reaction (1st rxn type)

Molar volume of a gas

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