properties of bases

strength of bases

The strength of bases is measured on a scale called the pH scale, which ranges from 0 to 14. On this scale, a pH value of 7 indicates a neutral solution, and a pH value greater than 7 indicates a basic solution. The higher the pH value is, the stronger the base. The strongest bases, such as drain cleaner, have a pH value close to 14.

detecting bases

Certain compounds, called indicators, change color when bases come into contact with them, so they can be used to detect bases. An example of an indicator is a compound called litmus. It is placed on small strips of paper that may be red or blue. If you place a few drops of a base on a strip of red litmus paper, the paper will turn blue. You can see this in the Figure 1.1. Litmus isnt the only detector of bases. Red cabbage juice can also detect bases, as you can see in this video. Click image to the left or use the URL below. URL: Drawing of red litmus paper turning blue in a base.

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what are bases

Bases are ionic compounds that produce negative hydroxide ions (OH ) when dissolved in water. An ionic com- pound contains positive metal ions and negative nonmetal ions held together by ionic bonds. (Ions are atoms that have become charged particles because they have either lost or gained electrons.) An example of a base is sodium hydroxide (NaOH). When it dissolves in water, it produces negative hydroxide ions and positive sodium ions (Na+ ). This can be represented by the equation: H O 2 NaOH OH + Na+

properties of bases

All bases share certain properties, including a bitter taste. (Warning: Never taste an unknown substance to see whether it is a base!) Bases also feel slippery. Think about how slippery soap feels. Thats because its a base. In addition, bases conduct electricity when dissolved in water because they consist of charged particles in solution. (Electric current is a flow of charged particles.) Q: Bases are closely related to compounds called acids. How are their properties similar? How are they different? A: A property that is shared by bases and acids is the ability to conduct electricity when dissolved in water. Some ways bases and acids are different is that acids taste sour whereas bases taste bitter. Also, acids but not bases react with metals.

uses of bases

Bases are used for a variety of purposes. For example, soaps contain bases such as potassium hydroxide (KOH). Other uses of bases can be seen in the Figure 1.2.

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instructional diagrams

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questions

an example of a base is sodium hydroxide (naoh).

-->  a. true

b. false

bases feel slippery to the touch.

-->  a. true

b. false

bases can react with metals.

a. true

-->  b. false

bases turn red litmus paper blue.

-->  a. true

b. false

bases are used to make

a) soaps.

b) cleaning products.

c) concrete.

-->  d) all of the above

the strongest bases have ph values close to

a) 0

b) 5

c) 7

-->  d) 14

diagram questions

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