Class+Notes

08hhufdrdr

This page is based off of the above file, PDF 19: Acid Base Notes

toc

-Acids
Acids are elements or compounds that release positive hydrogen ions called cations (H+ + H2O= H3O+) in water. When placed in water, these cations combine to form hydronium ions. Properties of acids include sourness, electrical conductivity, and corrosiveness (ability to cause metals to rust).

//You should be know the definition of an acid as described above- JT.//

-pH
Finding the pH is a way to find the acidity or alkalinity of a substance. The "p" stands for “Potenz” and the H means “Hydrogen.” pH levels range from 0-14, and the pH level of an acid would be 0-6.9 (doesn't make sense). The scale ranges from 1-14. A substance with a pH level of 7 is neutral. A good example of a neutral pH would be distilled water. Acidic solutions have a pH of (not complete sentence). The pH level of a base would be 7.1-6.9. Alkaline solutions have a pH of 7.1-14. Neutral solutions are neither acidic nor alkaline.

Purchon, Nigel. "pH." __pH__. 10 Nov 2006. ICRA. 22 Feb 2007 <[|http://www.purchon.com/chemistry/ph.htm>.]

//You should be know the definition of pH as described above- JT.//

Examples of Acids: a) Acetic Acid- Vinegar b) Citric Acid- Oranges, Lemons



Figure 1. Chemical compostion of Citric Acid

"Citric acid." //Wikipedia, The Free Encyclopedia//. 13 Feb 2007, 23:43 UTC. Wikimedia Foundation, Inc. 22 Feb 2007 <[|http://en.wikipedia.org/w/index.php?title=Citric_acid&oldid=107944959>.] c)Ascorbic Acid d) Ascorbic Acid- Vitamin C e) Nitric Acid

Figure 2. Chemical compostion of Nitric Acid

"Nitric acid." //Wikipedia, The Free Encyclopedia//. 19 Feb 2007, 17:59 UTC. Wikimedia Foundation, Inc. 22 Feb 2007 <[|http://en.wikipedia.org/w/index.php?title=Nitric_acid&oldid=109343187>.] f) Acetylsalicylic acid- Aspirin g) Hydrofloric acid

//You should be able to provide examples of acids and be able to identify acids.- JT//

3) The strength of an acid is due to its ability to release the **hydrogen ions** from it.

//Make sure that you understand the above statement.-JT//

- Bases
a) Bases hydrogen and hydronium ions accept to make water. (H+ + OH- = H2O) b) Bases are commonly associated with a.hydroxide ion. c) Bases are used in soaps and are also corrosive like acids. d) Bases are known to taste bitter

//Make sure that you understand some of the properties of bases and know the above definition.- JT//

Some examples for bases are:



Figure 3. The base Ammonium Hydroxide.

"Acid Base Titration Techniques." 22 Feb 2007 <[|http://dbhs.wvusd.k12.ca.us/webdocs/AcidBase/Lab-AcidBaseTitration/Bottle-Ammonia&vinegar.JPG>.]



Figure 4. The base Milk of Magnesium

"Phillips Milk of Magnesia, Wild Cherry." __IBS Tales__. IBS Tales. 22 Feb 2007 <http://images.google.com/imgres?imgurl=http://www.ibstales.com/images/products/cherry_milk_of_magnesia.jpg&imgrefurl=http://www.ibstales.com/cherry_milk_of_magnesia.htm//

You should be able to recognize the names of a few common bases- realizing that the word "hydroxide" is often associated with a base.- JT

pH- Hydronium Ion Potential
- How acidic or basic a solution is - Ranges from 0 - 14 - Neutral solutions are at a pH of 7 - pH is directly related to the hydronium ion and hydroxide ion concentrations in a solution - The pH scale is a log (base 10)scale - Something with a pH of 1 is acidic - A solution that has a pH of 14 is 1 x 1014 times more Basic than that of a solution at pH 1.

You should be able to describe the properties of the pH scale and be able to calculate difference in acidity or alkalinity (base) between two solutions of differing pHs. -JT



Figure 5. An image of a pH scale showing what common substances are at certain pH levels.

"Chemical Compatibility." __Dosmatic__. Dosmatic U.S.A., Inc.. 22 Feb 2007 <[|http://www.dosmatic.com/index.php?page=bguide/chemcompat>.]

Take a good hard look at this image and be able to describe it.- JT

- How is a solution tested for pH
a) litmus paper ---Blue and Red Litmus Paper- filter paper treated with a chemical (usually extracted from lichens—which is an organism that is a combination of fungi and algae) that reacts to different conditions of pH. When blue litmus paper turns red the pH of the substance being tested is acidic. Whereas, when the red litmus paper turns blue the substance being test is alkaline (basic).] b) pH probe d) Red Cabbage Juice- when dipped in a solution, it gives you a colour. Using the colour you can find the approximate pH. For example, the colour was blue then the pH is likely to be 8, if the colour is red then the pH is likely to be 2

Helmenstine, Anne Marie. "How to Make Red Cabbage pH Indicator." __Acid-Base Chemistry__. About, Inc.. 21 Feb 2007 <[|http://chemistry.about.com/library/weekly/aa012803a.htm>.]

You should be able to describe the tests we conducted to determine the pHs of solutions. Make sure you understand which are more accurate. -JT

- Neutralization
- the reaction between an acid and a base to form salt water in an attempt to get the pH closer to 7, or closer to being a neutral solution

Figure 4. "BBC Homepage." __GCSE Science Chemical Reactions__. 22 Feb 2007 http://www.bbc.co.uk/schools/gcsebitesize/img/gcsechem_59.jpg

- Look at Figure 4. Do you know what color blue l.p. turns in an acid? in a base? Do you know what color red l.p. turns in an acid? in a base? What happens in both of these situations if the solution is neutral? - JT Neutralization Complete neutralization can take place when a strong acid, such as hydrochloric acid, HCl, is mixed with a strong base, such as sodium hydroxide, NaOH. Strong acids and strong bases completely break up, or dissociate, into their constituent ions when they dissolve in water. In a neutralization reaction in which both a weak acid and a weak base are used, complete neutralization can occur if the acid and the base are equally weak. The heat produced in the reaction between an acid and a base is called the heat of neutralization.

"neutralization." __neutralization-Fact monster.com__. 2007. Pearson Education. 22 Feb 2007 http://www.factmonster.com/ce6/sci/A0835329.html.

- Be able to describe neutralization as above. If an acid such as HCl is added to NAOH what are the resultant products? Is this an exothermic or endothermic reaction? We did this reaction in our Reaction Lab! - JT//

media type="youtube" key="wHDWcvG3Nw8" width="425" height="350" Video 1. pH test and neutralization

No name given, "Kangen water pH test." __YouTube__. 2007. YouTube. 26 Feb 2007 <[|http://youtube.com/watch?v=wHDWcvG3Nw8>.]