acids, bases and salts

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ACIDS, BASES AND SALTS

All acids produce H+ aq ions when dissolved in water. Acids are NEUTRALIZED by BASES such as METAL OXIDES and METAL HYDROXIDES.

alkalis are soluble bases and all alkalis contain OH- aq ions.

INDICATORS

acid alkaline

litmus paper pink blue

methyl orange red yellow

phenolphthalein colourless pink

pH scale-

0= really acidic

14= really alkaline

7= neutral

In order for an acid to form, water must be involved to break up the ions e.g.

hydrogen chloride + water --> hydrochloric acid

SOLUBILITY RULES

all sodium and ammonium salts are soluble.

all nitrates are soluble

most chlorides, bromides and iodides are soluble

most sulfates are soluble except barium and lead

most carbonates are insoluble except sodium, potassium and ammonium salts

MAKING INSOLUBLE SALTS BY PRECIPITATION

Mix two appropriate soluble salt solutions e.g. for lead chloride you would need to choose a solution contain lead inos and one with chloride ions.

choose a nitrate and a sodium salt because these are ALWAYS soluble e.g. lead nitrate solution and sodium chloride solution. lead nitrate + sodium chloride --> lead chloride + chloride solution

filter, wash and dry the solid precipitate.

MAKING SALTS USING ACIDS

ACID + METAL --> A SALT + HYDROGEN this is not suitable for making salts using group 1 metals because they are too reactive.

ACID + BASE --> A SALT + WATER This is not suitable for soluble bases. This reaction might need warming up to speed up the rate.

ACID + METAL CARBONATE --> A SALT + WATER + CARBON DIOXIDE

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