Thursday, July 17, 2008

Home Chemistry

We're doing some home chemistry this summer because both our kids like doing experiments on school break. There are many chemistry resources on the web. Our son's in middle school and daughter's in 6th, I combined a little teaching about chemical compounds and the "logic" of balancing chemical equations with look-and-see learning from home experiments.

The theory of oxidation grew out of theories regarding combustion. The Flemish physician Johann Baptista van Helmont was the first to hypothesize that a spiritus sylvestre (wild spirit) was responsible for combustion. This wild spirit theory evolved in to the concept of a substance phlogiston that could be driven out by the burning process.

French chemist Antoine Laurent Lavoisier (1743–1794)theorized instead that combustion was the mechanism by which a substance combined with oxygen. He advanced his theory by meticulous experiments involving the weighing of material. The oxidation theory was born.

I found the Home Chemistry Blog and the pennies and vinegar experiment seemed like a great start to our discussion of oxidation. Vinegar comes from French, vin-algre, or wine-sour.

I. Dull to Shiny Penny

1. Mix 1/4 c vinegar with 1 teaspoon salt. Collect a dozen or so dull / black pennies. Dip one into the mixture so that it is half shiny.

A dark penny has been oxidized by oxygen in the air. Instead of copper (Cu), it is CuO, or copper oxide.

II. Verdigris and Copper Plating Iron Nails

1. Put the remaining pennies in the vinegar-salt mixture. Wait for about an hour.
2. Rinse half of the pennies in water, and the other half let dry on a paper towel.
3. Now add some nails to the vinegar-salt solution that had the pennies. You can use galvanized or non-galvanized nails if you have them. We added a paper clip and aluminum nails that we found.
4. Check back in 10-15 minutes. Do you see small bubbles forming on some of the nails? It's hydrogen gas being released from a reaction between the vinegar (acetic acid) and metal oxides.
5. Check back in an hour. The control (non-washed pennies) should have a nice verdigris finish (like the Statue of Liberty!) and the iron nails will be copper-coated, and so light brown. Our paper clip also became brown, and our aluminum nails were unchanged.

The reactions: CuO + CH3COOH (vinegar) + Salt (increases ionic strength) --> Copper acetate (CuOCH3CO2-) + H2 (hydrogen gas).

When the iron nails are put in the copper solution (made from the pennies), the reaction is: Cu2+ (aq) + Fe (s) --> Cu(s)+ Fe2+ (aq), where aq = aqueous and s = solid. Copper is more avid for electrons than iron so it steals electrons in the solution to become solid plating.

The history of copper dates back 1000's of years. At left is a copper-headed axe found in Europe with the body of a 5200 year old corpse(called Otzi).

History of Combustion
Armchairchemistry
Kent's Chemical Demos
Chemistry, Matter, and the Universe Free Course
Chemistry Songs
Chemistry Links
History of Chemistry

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Previous Latin Sayings of the Week

"Soli deo gloria." - For the glory of God alone.


Christus resurrexit! Vere resurrexit! - Christ is Risen! He is risen, indeed!



"Lex malla, lex nulla." - St. Thomas Aquinas
(A bad law is no law.)


"Cantantes licet usque (minus via laedit) eamus. " - Let us go singing as far as we go: the road will be less tedious.


"Caelitus mihi vires." - My strength is from heaven.

"Magnificat anima mea Dominum, et exsultavit spiritus meus in Deo Salvatore meo" - My soul doth magnify the Lord, and my spirit hath rejoiced in God my Savior (Luke 1:45)

In Omnibus Ipse Primatum Tenens “That in all things He (Christ) might have the preeminence.” (Colossians 1:16-18)


"Qui bene cantat bis orat." - He who sings well, prays twice - (St Augustine)

"Nos fecisti ad te et inquietum est cor nostrum donec requiescat in te." -
Thou hast made us for Thyself, O Lord, and our hearts are restless until they rest in Thee. (St Augustine)

"Caelitus mihi vires
." - My strength is from heaven.

"Ubi caritas et amor Deus ibi est." - Where there is charity and love, God is there.

"Nisi credideritis, non intelligetis ."

Unless you will have believed, you will not understand. - St Augustine

"Deo vindice" - With God as Protector


"Credite amori vera dicenti." - Believe love speaking the truth. (St. Jerome)


De vitiis nostris scalam nobis facimus, si vitia ipsa calcamus." - If we tread our vices under feet, we make them a ladder to rise to higher things. (St. Augustine)

Dei gratia - By the grace of God

Verbum Domini Manet in Aeternum. - The Word of the Lord Endures Forever.

"Est autem fides credere quod nondum vides; cuius fidei merces est videre quod credis." - Faith is to believe what you do not see; the reward of this faith is to see what you believe. (St. Augustine)

"Deo iuvante" - with God's help

"Ut In Omnibus Glorificetur Deus." - That God may be glorified in all things

"Pax vobiscum." Peace be with you.

"Jubilate Deo." Be joyful in the Lord.

"Ille vir, haud magna cum re, sed plenus fidei." He is a man, not of ample means, but full of good faith.

"Facit enim mihi magna qui potens est." - For He that is mighty does to me great things.

"Oremus semper pro invicem." - Let us ever pray for each other.

"Distrahit animum librorum multitudo." - Seneca
A multitude of books distracts the mind.

"Nullam est nunc dictum, quod sit non dictum prius." - Terence
There is nothing said now, that has not been said before.

"Nosce te ipsum." - Plato
Know thyself.

"Non mihi, non tibi, sed nobis" - Not for you, not for me, but for us.

"Primum non nocere." - First, do no harm (Hippocrates)

"Est autem fides credere quod nondum vides; cuius fidei merces est videre quod credis." - Faith is to believe what you do not see; the reward of this faith is to see what you believe. (St. Augustine)

"Deo iuvante" - with God's help

"Ut In Omnibus Glorificetur Deus." - That God may be glorified in all things

"Pax vobiscum." Peace be with you.

"Jubilate Deo." Be joyful in the Lord.

"Ille vir, haud magna cum re, sed plenus fidei." He is a man, not of ample means, but full of good faith.

"Facit enim mihi magna qui potens est." - For He that is mighty does to me great things.

"Oremus semper pro invicem." - Let us ever pray for each other.

"Distrahit animum librorum multitudo." - Seneca
A multitude of books distracts the mind.

"Nullam est nunc dictum, quod sit non dictum prius." - Terence
There is nothing said now, that has not been said before.

"Nosce te ipsum." - Plato
Know thyself.

"Non mihi, non tibi, sed nobis" - Not for you, not for me, but for us.

"Primum non nocere." - First, do no harm (Hippocrates)

"Dei plena sunt omnia." - Cicero (All things are full of God.)