Silver Tarnishes Because it Reacts with Sulfur Gases and Oxygen Combined?

Oxidation of Silverware Caused by Reaction with Oxygen Gas and/or Hydrogen Sulfide Gas?

Silver(I) Oxide

Tarnished Metal

One of the common misconceptions about silver plated serving ware is that it tarnishes because oxygen comes into contact with silver and forms silver(I) oxide (Ag₂O).  The black color of silver oxide makes it easy to mistake silver oxide as the patina on our silver serving ware. Some sources include oxygen in the chemical reaction, however the black coating on the surface of the silver is due to reaction with hydrogen sulfide and oxygen both. Oxygen does the oxidizing but silver ends up with sulfur to counterbalance the Ag+ charge.

Silver Sulfide

Silver sulfide (Ag₂S) is actually responsible for the oxidative coating.  To tarnish silver it must react with "sulfur gases."  The most common sulfur gas is hydrogen sulfide H₂S [1].

Sulfur Dioxide

Hydrogen sulfide has a structure similar to water, where the O is substituted with an S.  "Hydrogen sulfide often results from the bacterial breakdown of organic matter in the absence of oxygen, (Wikipedia)."  It is a weak acid and can donate an H+ to be left with HS-.

A simplified chemical reaction of oxidizing silver is [2]

4 Ag(s) + 2 H₂S(g) + O₂(g) 2 Ag₂S(s) + 2 H₂O(g)

However tarnishing is a multistep process. This reaction "is a short-hand or end-result of many transformations. " The detailed reactions are given below.

Reduction and Oxidation Explanation

In this reaction silver goes from an oxidation state of zero in the reactants to +1, the oxidation state in the products (oxygen has a -2 oxidation state in water).  Hydrogen remains the same at +1 and sulfur remains at an oxidation state of -2 on both sides of the equation.  Oxygen is in its elemental form and has an oxidation state of zero on the reactants side and -2 on the products side.  Silver is oxidized (reducing agent); its oxidation number increases and oxygen is reduced (oxidizing agent). 

Can Hydrogen oxidize Silver?

Another alternative reaction given does not include oxygen.  If you were to look at a table of electromotive force you would know that this could not happen the EMF would be -0.8Volts.

2 Ag(s) + H₂S(g) ---> Ag₂S(s) + H₂(g)

In this reaction hydrogen is reduced from +1 to zero and silver is oxidized from zero to +1.The oxidation state of sulfur remains unchanged. 

Multistep Tarnishing of Silver

Corrostion and tarnishing are multistep reactions. Even the formation of rust is not a simple combination of iron and oxygen.  Water is necessary for rust to form. Upon closer research of articles on the internet there is one website that talks about the multistep mechanism of silver tarnishing.  

8Ag + 4HS^- <---> 4Ag₂S + 2H₂ + 4e^-
0₂ + 2H₂O + 4e^- <---> 4OH-

What would be the sum of the EMF of these reactions?

Ag ---> Ag+ + e-                                    EMF = -0.799V
2H+   --->2e-+H₂                                   EMF = 0V
 0₂ + 2H₂O + 4e^- <---> 4OH-                     EMF = 0.4V  

This reaction would not be spontaneous because the sum of the EMF's would be negative (-0.799+0.4=0.399V) 

If the reaction were under acidic conditions the EMF would be large enough to tarnish the silver:

 0₂(g) + 4H+(aq) + 4e^- <---> 2H2O(l)                EMF = 1.23V  

-0.799+1.23= 0.431V

Why Doens't Silver Oxide form When Silver is Tarnished?

Activity Series

Alkali and alkaline earth metals are the most active, most easily oxidized because their electron can be easily ionized.  However transition metals and "noble"metals such as silver hold on to their electrons more tightly. Oxidation, therefore has a relationship to ionization energy. The lower the ionization energy the easier it is to oxidize an element.

 

Silver is a Less Reactive Noble Metal

One reason why silver does not form silver oxide when it reacts with air is that silver is not as reactive as some other metals, where reactivity is defined as the ability to form a positive ion. Reactive metals tend to have 1 valence electron in the s shell or the p shell, valence electrons and ionization energies (energy to eject an electron).

So why does silver react with sulfide ions in solution vs. hydroxide? When silver gets oxidized sulfur is probably the first thing it sees and so it reacts with it.  To get it to react with oxygen and form an oxide it would take converting OH- or water to oxide (O²⁻).  First the silver might have to form Ag(OH) in the steps similar to how the iron in steel becomes rust.

 

Solubility of Silver Sulfide and Silver Hydroxide in Solution?

The solubility product constant for silver is  6x 10-51, which means that not much Ag2S does not like to form the ions Ag+ and S-, whereas Ag(OH) is

1.52 x 10 -8.  Silver hydroxide is much more soluble in water.  It is therefore most likely that silver does not form silver oxide because it is more soluble in water and solid Ag(OH) is less likely to form than solid Ag2S in solution.

A Green Way to Remove Silver Sulfide Tarnish

A common way to remove the silver sulfide tarnish is to put the silverware in a solution of baking soda, warm water and aluminum.  Aluminum is very reactive and will form aluminum oxide (Al₂O₃), a white powder.  This is why we add baking soda.  It creates a basic solution that helps to break through the outer aluminum oxide layer.  The chemical equation for baking soda in water is [4]

NaHCO₃ (baking soda) + H₂O → H₂CO₃ + Na⁺ + OH^-

The reaction of silver sulfide with Aluminum can be expressed in the following reaction(s):

3 Ag₂S(s) + 2 Al(s) ---> 6 Ag(s) + Al₂S₃(s)

3Ag₂S(aq) + 2Al(s) → 6Ag(s) + 2Al⁺³(aq)+ 3S^{- 2}(aq)

or including the water

3Ag₂S(aq)+ 2Al(s) + 3H₂O(l) → 6Ag(s) +Al₂O_{3 (aq)} + 3H₂S(g) 

 

 Breaking the Reaction into Two parts:

OXIDATION:   2 Al(s) + 6 OH– (aq) –––> Al2O3(s) + 3 H2O (l) + 6 e–

REDUCTION:  Ag2S(s) + 2 H2O (l) + 2 e–   –––>   2 Ag(s) + H2S (aq) + 2 OH– (aq)
                                                                                                        

3 Ag2S(s) + 2 Al(s) + 3 H2O (l) –––> 6 Ag(s) + 3 H2S (aq) + Al2O3(s)  

 

Aluminum Sulfide is a white powder.

Aluminum Sulfide

You Tubes Related to This Article:

Silver Tarnish Removal (II): Chemical Equation

Reducing Agents: Preparation and Tests for SO2 and H2S.

How to Use Sprites with HTML

The homework for my web graphics class this week was to use sprites with a nav bar and HTML. 

Fireworks

First I created the sprites in Fireworks.   The image looks like this:

The article that I was going by did not say anything about creating states.  It just said export it as a nav.png  I did export the image but only in a .gif file.  Firefox (version 5) would not give an option to export in .png I used paint to convert it.

HTML

Next I wrote the HTML passed W3C with 2 warnings.

Use the W3C Validator at http://validator.w3.org to check for XHTML syntax errors.

I was not able to get the sprite to work at first. When I removed the css style sheet I could see the next from the nav bar.
so it must have been something to do with the css.

CSS file is called mod9css.css

Last I wrote the CSS.  It just tells which part of the png file to show but the part I don't get is how does the mouse know where you are.
I am not sure what all the # symbols are for.  Active focused selected and hover seem like they are states that you should set up in Fireworks.

The page looks like this right now.   The nav.png file is being called because you can see the graphics, but the css is not rendering correctly.  When I replace the nav.png with the one in Blackboard things look worse.  Nothing shows up.

No errors found on w3c validator.
Use the W3C Validator at http://jigsaw.w3.org/css-validator to check for CSS syntax errors. 

One problem I had was that I did not slice my file up in to pieces.  It was one big piece.  At first I though I was supposed to use states, but it was the slice that I wanted.  This is why I could not save the file as a .png.  It only gave me at. gif as an option.

The image is aligned property but sprites do not work.

CSS Sprites only work when the CSS is in the HTML file and not a separate file.

Connecting Your Domain Name to Google Apps & Sites

Once you have purchased a domain name and created an account on Google sites you will need to route your domain to Google Apps/Sites.  With this you will have free email, free calendar and free web hosting.  The only cost to you is the annual renewal of the web domain name.

Google Sites is a subset of Google Apps.  Apps includes email, calendar and a whole sets of apps. With the mail app you can add multiple users.

Login to you web domain DNS host.  DNS = Domain Name Service.  In our case it is DNS exit. The screen will look like the image below.

I used ChicagoIBS.org as my site to test that this work out.

Google

DNS Exit

Alias Records -  In this step you will shorten the webpage names for the email etc.  

1. Search for the words "Google App Free.  
2. You will find this domain name. https://www.google.com/a/cpanel/standard/new3
3. Type in the name of your domain
   chicagoibs.org in my case.
4. Click on Set Up Apps
5. Click Sites Button
6. Click Next or Do this later
7. Exit this section
8. Go to Settings > General >Change URL
9. Change URL for ALL domain services
10. In this step you will shorten the webpage names for the email etc.  Click the 2nd bullet of each section.  For example in my case mail.chicagoibs.org Do the same for calendar, docs and sites.
11. Click Continue
12. Go back in to DNS Exit to to Edit DNS
13. Add Alias, external host - save changes
14. Click - I've completed these steps
15. Go to Organization and Users on the main navigation bar
16. Go to services
17. Turn on contacts, drive and docs, gmail, google calendar, google sites, google talk (the first six)
18. Save changes
19. Go to Setup > next > alternate method >domain name provider > other
20. Go back to the DNS Panel >TXT Records> Add Text > Text Data > Add Text > Save changes
21. Wait 5-10 minutes for DNS. Click Verify > Continue > changes to eamil unclick all
22. Click setup >do later/next until done
23. Test for sites.chicagoibs.org ( fill in your name)
24. Delete the TXT Record. Save

The email is setup in DNS Exit with MX

1. Email > Organization & Users > services
2. Settings > email > MX setup instructions
3. Setup gmail > next > other > next
4. MX on DNS > save change > wait 24 hours > next > yes changed > click back to where you started.
5. This may take 24 hours so wait and come back and check it.
6. To check it setting > email > MX record
7. mail.chicagibs.org

What Other Resources Exist in Our Galaxy to Support Life?

In the last article we discovered that there are six places in the universe where life might be found in an article by Seth Shostak at SETI on Space.com. If we traveled to these six places what resources would we find.  What life could possible live there?


6 years away from Earth - Enceladus, Titan, Europa, Callisto and Ganymede

Europa
Water under 10 miles of ice & Geothermal heat - Europa is dark and cold - No Photosynthesis 

Enceladus

Water and chemicals - On Enceladus you have a moon with volcanic activity, a silicate crust, frozen exterior, hydrocarbons, ammonia, propane, ethane and acetylene, in the atmosphere, ice and water.  For humans to live on Enceladus you would need oxygen and carbon dioxide. Humans would be bouncing around all over the place on Enceladus since it is 1/7 the size of our moon. Cold on the outside, warm on the inside of the moon.

Titan

Liquid Fuel, Nitrogen, Solar Wind, Organic Smog, Frozen Water, Wind, Liquid Methane Rain, Dunes, Rivers,  Lakes, Hurricanes, Lots of complex chemicals, dry atmosphere, warm upper atmosphere, cold surface, only gets 1% of sunlight that Eath Does, Geologically Young, Habitable 6 billion years from now  - Titan is much larger than Enceladus and should therefore have more gravity. There is an abundant source of fuel - ethane and methane.  The moon is very cold. Methane cycle analogous to Earth's water cycle. Titan is bigger than our moon and smaller than Earth.

Callisto and Ganymede

Liquid oceans under 60 miles of rock 

Mars

150- 300 Days - Mars Salty Water - Beneath the surface of Mars - salty water.

Venus
97-153 days- Heat, sulfur dioxide and carbon monoxide, floating microbes, acidic clouds

How far are you willing to travel to find these resources ?

Let's Pretend We are on a Spaceship

One of the resources that stand out from the six most likely places is water that is hard to access (except for on Enceladus), geothermal activity, lack of sunlight/cold environment, chemicals that a human could not normally breathe in unless they lived in one of the most polluted cities in the world and were exposed to them over long periods of time and their bodies adabped.  The only place where there might be enough sun to ever have photosynthesis could be Mars or Venus.

Perhaps Enceladus, Titan, Europa, Callisto and Ganymede are an example of what was happening after the ice age on earth and Mars and Venus are examples of what could happen if Earth warmed up too much, i.e. global warming.  If carbon monoxide exists on Venus and sulfur dioxide, it would not be too far off to think that carbon dioxide could exist as well. 

Enceladus is the Artic Cordillera an area of the Anartica in Northern Canada that was once volcanic.

Titan is am extremely cold city with the worst air pollution on Earth with areas that are like Earth's dessert - Nambi Dessert.

Mars has been compared to the Atacama dessert.

Venus is basically a very hot highly polluted city where you could feed off of microbes in the upper atmosphere if you were a preditor. This is an extreme simplification, but if you suspend your logic then the model might be applicable.

So are the moons of Jupiter and Saturn to cold for humans to ever inhabit.  Could something warm them up?  Or do we just need some fuel and water to survive there?

Looking for Life

Why Study Astronomy?

Map of the Universe

On a recent weekend trip my husband and I went on a tour of Yerkes Observatory.  We enjoyed the tour and learning about lens and mirror telescopes and all about the famous people who had passed through Yerkes, which included Einstein and Hubble.

In searching for a map of the universe I found that there are 45,000 galaxies as shown by the 2MASS Reshift Survey.

While reading the information I read about a number of different stars and stellar systems like Eta Carinae (image below), Andromeda m31, Abel 2218, Coma Berenices NFC 4881, and Messier 100.  I also read about the Sofia HAWC program.

One of the questions that comes up is why are we studying stars?  They are so far away that it feels that we might never be able to visit.  The answer is inevitably that we want to know if there is life elsewhere in the universe.  If you are interested in physics, chemistry, biology, science then you should be interested in astronomy. Another reason is that we want to know what is going on in the universe to protect us from any activity  that might be going on - asteroids, meteorites and supernovas.

When the Hubble telescope took all of those fabulous pictures is when we were able to turn the invisible into a visible.  But what do all the pretty pictures mean?

Eta Carine

Eta Carinae is way more powerful than our sun, very active and really far away from us, 7,500 light years.  In the image the star is actually in the middle and it is surrounded by two dumbells which are called  Homunculus Nebula. Homunculus is little man in Latin and represents left over bits of stuff after an explosion. Some people think there is a black hole in the middle of each lobe. 

On the tour what I read is that Eta Carinae is going to live a much shorter life than our sun.  So could another earth be located there?  If it will not be there for long as Eta Carinae will be exploding "soon."  Well soon on the universe's time scale -  in a few years, or in our lifetime or maybe in a million years. Well who can predict it anyhow.  Eta Carinae puts out a lot more light than the sun, so if we lived there we would be barbecued with in a nanosecond.

After doing a bit more reading and finding the Space.com website to be quite interesting, it seems that our own Milky Way Galaxy is teeming with life, microscopic life most likely. There is proof for it.

Enceladus, on of the moons of Saturn, is the most likely place to find life in our galaxy. It is located in the E-ring of Saturn and is 1/7 the size of our moon. It has cold liquid water and is geologically active with many chemical compounds such as hydrocarbons, ammonia, propane, ethane and acetylene and plumes of gas that are ejected from the surface.  The chemical composition of the moon is silicate in nature and the surface has craters and canyons.  Many new classes of charged particles and nanograins have been found on Enceladus.  It takes anywhere from 6-3 years to arrive on Enceladus.

Exploring our galaxy is the best first step and a heck of a lot easier than looking billions of light years away.  At least for now.

Migrating to WordPress

Why I Migrated My HTML page to WordPress

The page was slow.  It took 20 seconds to load.
The ads I used to draw people to my page defeated the purpose of advertising.
The landing pages needed improvement.
The graphics needed improvement

What I've learned about WordPress in less than 24 hours
WordPress is a fancy version of Google Sites and other prepacked webpage building software - content management system (CMS) - that allows you design a website without needing to write code like HTML and CSS. It is built on PHP and MySQL.

The first steps are to decide the name (domain name) of your webpage and find a place where the website files and data will live (hosting).  The name of my current website is www.chicagoibsibd.org  I bought the name on in on DNSexit.  Our website is hosted on a LAMP (Linux, Apache, MySQL, PHP) server.  When WordPress is downloaded what you get is a bunch of PHP files.  But these files do not reside on the computer you are sitting at.  The PHP files live on the server computer. These PHP files allow the front page of the website to talk with the server in a dynamic interactive way.  You can think of front end and back end to refer to what is going one relative to the person sitting surfing on their computer.

Theme & Created Pages
The theme that we selected was Twenty Eleven.  It is a good theme to pick if you want your page to be found by people surfing the net and Googling a particular word on your page.  I first started by creating a graphical header in Adobe Fireworks with free images found on stock xchng of a skyline.  I'd like to shrink down the size of the header - work in progess.Then I created 9 webpages and did a cut and paste of the text in the central part of the page.

Multisites and Domain Mapping ( Day 3 Octboer 19) I am using http://www.0ehrl1.com/ to create the WordPress  prototype site.  There is only one installation of WordPress on our server. At first we had only this one site, 0ehrli.com but now we want to have new websites and need to create subdomains. In addition to creating multisites, we have to map the domain to actual DNS subdomains.  We also created a child theme.

WAMP vs. LAMP and transferring files
In order to change the parent theme that comes with the Twenty Eleven and Twenty ten themes you have to have access to the wp-content > themes.  The Lynda.com files explain how to transfer files when WordPress is hosted on a Windows WAMP server.  In our case we have an Linux LAMP server and have to find a way for the front end developer, me, to pass my files to the LAMP server on the back end.  One option in FTP.  Another option might be Dreamweaver.

Plugins & Widgets
I installed a jetpack plugin after listening to the Lynda.com videos.  One of them was called a You Tube channel gallery. When I installed the jetpack it seemed to direct me to WordPress.com to login, which confused me, but after doing this all of the plugins I selected were there.

What I am Working on Now

1. YouTube Video on each page
2. Area where I can put an image
3. Link to Ning
4. Signup for Mailchimp

Day 2 of WordPress
I am watching the videos for WordPress 3: Building Child Themes.  Chapter 2.3 has to do with changing the header size and Chapter 5.1 has to do with inserting fixed sidebars.  When I purchased the Lynda.com package I ordered the supplemental material.  This was a good thing because these files (The New Cool) have a lot of prepackaged code that will allow you to easily change things. 

Where are my files?
Where the files are located is an interesting question.  This page explains it well. This is another with the template hierarchy.  How to create a Wordpress Theme from scratch.

Well I am going to take a break.  I need to learn how to log in to the LAMP server before I can proceed to modify my themes.
How do I place images and video in the sidebar?

Child Themes

How do I make a folder in the WordPress PHP files on the server?  Can't seem to do it.

I have now listened to most of the beginner Lynda.com  I am looking for how to make the header smaller.  Understanding the child themes seems to be the next step. This blog was good:

WordPress 3: Building Child Themes notes

Functions.PHP (Lynda.com) Child WordPress Intermediate
To change the size of the header you have to go in to themes and twenty ten (or elevent) folder and the functions.PHP file.  A function creates the header image.


Twenty eleven - make header image smaller and move to top (7 posts)
http://wordpress.org/support/topic/twenty-eleven-make-header-image-smaller-and-move-to-top

Day 1 Oct 16

1. Open up my website
2. Open up WordPress.org
3. Download the latest copy.
4. Find a place to put my website as a test location.  Eventually I need to move the WordPress page to that it resides at my domain location.
5. I need to ask the web guy who runs the basement lab how he organized things.
6. http://[websitedomain]/wp-admin
7. Create a subdirectory?  I did not do this
8. Select a Theme 2011
9. lynda.com  These were helpful
10. Quick Edit allows you to change the hierarchy of the pages.
11. I tried to use the showcase template with the posts on the 2011 theme but it didn't work quite right.
12. What do I do about the widget and post area?  I want to put a You Tube in there and the call to action to Join Ning and sign up for Mail Chimp.

Day 2
Lynda Chapter 12 Jetpack & Widgets
I seem to have missed the part where they explain how to install these.  I went to the list of plugins and I am looking over the ones that have 5 stars for a rating. Activated the plugin.

http://wordpress.org/extend/plugins/jetpack/

I want to change the size of the header on 2011

http://en.support.wordpress.com/featured-images/

I looked at this blog for some help.

http://www.wealthydragon.com/2011/12/01/convert-html-website-to-wordpress-process/

Eding CSS

http://en.support.wordpress.com/custom-design/editing-css/

Time spent:

Oct 16 4pm - 7:32 pm  going to library
Oct 17 6 am - 7 am
7:30 - 8:30 Getting Things Done pg 59

Starting the Job Search from the Ground Up

Today I wipe the slate clean and eliminate the obstacles.  This has been an interesting year but I've eliminated one job title from my list.  Time to start over.

I have to admit that I've been lazy, but perhaps I can call it processing.   

I've had numerous calls from recruiters this year.  The statistics and distributions of job type and industry has given me some information on the job market.  But what do I want?  It is time to get of my rear in gear and hit the pavement to figure that out.

I have had three interviews this year.  One of them was close to what I used to do as a scientist minus the beakers and lab equipment, but the other ones were pretty different.  The problem was that I was not ready for theses interviews.  They plopped into my lap like a gift from heaven, but I was not prepared.  "Chance favors the prepared mind,"  as someone once told me.  My mind was definitely not prepared.

Even if other people help you, if you are not ready yourself you will not be able to seize the opportunity.  So I finally woke up and walked out of my cocoon and went to a series of four seminars through the local job networking group.  It made me stop feeling sorry for myself and swept the cobwebs out of my brain.  I like to envision them that way.  They are the negative thoughts that linger and fester in there until we take some action to clean them out.

Life can be a positive chain reaction once we start moving in the right direction.  Thanks to my friends and family, I've been able to realize that I'm not a loser just because I don't have a job title.  There is the essence of me, my spirit and my personality that no one can take from me.

I am back in high gear looking for the yellow brick road and my ruby slippers.  I've already written my career marketing plan.  I am working on my handbill and my list of industries and companies.  I'm ready to figure out what I want to do for the rest of my life!