Acids and Bases

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Acids/bases in various indicators

Indicator: litmus paper, orig color: red, in an acid: red, in a base: blue
Indicator: litmus paper, orig color: blue, in an acid: red, in a base: blue
Indicator: universal indicator, orig color: green, in an acid: red/orange, in a base: blue/purple
Indicator: Methyl orange , Orig color: yellow orange, in an acid: red, in a base: yellow orange
Indicator: Phenolphthalein, orig color: colorless, in an acid: colorless, in a base: pink

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Tastes bitter
Litmus paper to blue
Feels slimy and slippery to touch

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Work in colors. Red litmus is a useful indicator. Red litmus red in acidic and neutral and blue in alkaline. Blue litmus blue in alkaline and neutral solutions and red in acidic solution. If unknown solution turns red litmus paper blue, solution alkaline. If unknown solution turns red litmus red and blue litmus blue, it means that it's a neutral solution.

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Acid Rain

What is acid rain?

Slightly acidic, contains Co2. When water vapor combines, makes more acidic (5.0 - 5.5) When fossil fuels burnt, sulfur dioxide and nitrogen oxide released. Cars and power stations, eg burning fossil fuels. Effect on aquatic: lowers pH level and so, the fish cannot live and die. Effect on forest: trees vulnerable to disease, extreme weather, and insects by destroying their leaves, damaging the bark and arresting their growth.Effect on soil: pH level lowered or reversed, altho needs to be optimum pH. Effect on Architecture and Buildings: when made with limestone, then corrode away. Effect on Public Health: asthma or bronchitis when inhaled. Reduce burning of fossil fuels, catalytic converters in cars reduce emissions. Adding lime to soil to neutralize it.

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Metal oxides

Metal reacted with oxygen will make oxide

Metal + oxygen = metal oxide 

Known as tarnishing 

     oil, paint, galvanizes (coating with another metal) - stops tarnishing. 

When metal oxides react with acid, salt and water produced and also heat 

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Tastes sour
Litmus paper to red
Metals to give off hydrogen gas

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Reactive metals

Acids will react with reactive metals, such as magnesium and zinc, to make a salt and hydrogen. In general:
acid + metal → salt + hydrogen
The hydrogen causes bubbling during the reaction, and can be detected using a lighted splint. You usually see this reaction if you study the reactivity series of metals.

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What are alkalis

Bases that dissolve in water are called alkalis. Copper oxide is not an alkali because it does not dissolve in water. Sodium hydroxide is an alkali because it does dissolve in water.
Alkaline solutions have a pH of more than 7. The stronger the alkali, the higher the pH number. Alkalis turn red litmus paper blue. They turn universal indicator dark blue or purple if they are strong, and blue-green if they are weak.

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What are bases

Substances that can react with acids and neutralise them to make a salt and water are called bases. They are usually metal oxides or metal hydroxides. For example, copper oxide and sodium hydroxide are bases.

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What are acids

Substances with a pH of less than 7 are acids. The stronger the acid, the lower the pH number. Acids turn blue litmus paper red. They turn universal indicator red if they are strong, and orange or yellow if they are weak.

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What's a neutral solution

Neutral solutions have a pH of 7. They do not change the colour of litmus paper, but they turn universal indicator green. Water is neutral.

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Acids and bases

When acids react with bases, a salt and water are made. This reaction is called neutralisation. In general:
acid + metal oxide → salt + water
acid + metal hydroxide → salt + water
Remember that most bases do not dissolve in water. But if a base can dissolve in water, it is also called an alkali.

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Acids and carbonates

When acids react with carbonates, such as calcium carbonate (found in chalk, limestone and marble), a salt, water and carbon dioxide are made. In general:

acid + metal carbonate → salt + water + carbon dioxide

One or more metallic elements combined with Co3 2 -

Examples of bases 

Salt produced in neutralization reaction is composed of the negative ion of an acid and positive ion of a base.

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Neutral substance produced from acid and alkaline reaction

Neg ion of acid, pos ion (always metal) of base 

Negative ion: ion gained electron, non-metal (anion)

Positive ion: ion lost electron, metal (cation)

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General formulas

Metal + acid > salt + hydrogen
Metal oxides + acid > salt + water
Metal carbonates + acid > salt + water + carbon dioxide
Acid + base > salt + water

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Forming chemical equations

1) figure out the reaction

2) workout reactants and products

3) write chemical equation. Check bonding

4) make sure it's balanced

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