bases and alkalis Flashcards by Unknown Unknown | Brainscape

Q

what is a base?

A

metal oxide or hydroxide.

they are ionic compounds containing oxide ions or hydroxide ions.

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Q

definition of base

A

a base can be defined as a substance that reacts with acid to give salt and water only. this reaction is called neutralisation.

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Q

what are soluble bases

A

alkalis when dissolved.

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Q

what is an alkali

A

a metal hydroxide which is soluble in water.

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Q

the 4 common alkalis

A

sodium hydroxide
potassium hydroxide
calcium hydroxide
aqueous ammonia
[spca]

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

all alkalis produce ____ ions when dissolved in water

A

hydroxide ions

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Q

physical properties of alkalis

[3]

A

alkalis have a bitter taste and feel soapy.
alkalis turn red litmus paper blue.
alkalis dissolve in water to form solutions which can conduct electricity.

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Q

do stronger acids or weaker acids conduct electricity better

A

stronger acids.

they dissociate more.

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Q

alkalis + acids =

A

salt + water

[neutralisation]

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Q

alkalis + ammonium salts =

A

salt + ammonia gas + water

Q

how to test for ammonia?

A

hold a moist red litmus paper at the mouth of the test tube; if ammonia gas is present the litmus paper turns blue.

Q

alkalis + metal ions(in a solution)=

A

precipitation of the insoluble hydroxides

Q

what is the pH scale?

A

it is a set of numbers from 0 to 14.

it indicates if a solution is acidic, neutral or alkaline

Q

how do you measure the pH of a given solution?

A

by using an indicator.

Q

what are indicators?

A

indicators are substances that have different colours in acidic and alkali solutions