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36 Cards in this Set

  • Front
  • Back

What is the pH of the strongest acid?

pH 0

What is the pH of the strongest alkali?

pH 14

What is an indicator?

A dye that changes colour depending on whether it's above or below a certain pH.

What neutralises an acid?

A base

What is an acid?

An acid is a substance with a pH of less than 7. Acids form H+ ions in water.

What is a base?

A substance with a pH of greater than 7. An alkali is a base that dissolves in water. They form OH- ions water.

What is the name for this general equation?


Acid + base ---> salt + water

Neutralisation

What is the definition of neutralisation?

A reaction between an acid and an alkali (a base) that results in a metal salt and water.

How else can neutralisation be seen/defined?

In terms of H+ and OH- ions. General equation:


H+ (aq) + OH- (aq) ---> H2O (I)

When an acid neutralises a base, what are the products described as being?

Neutral.

Name the four 'state symbols' and what they represent.

(s) - Solid


(l) - Liquid


(g) - Gas


(aq) - Dissolved in water

What substance must a metal react with to produce a salt?

An acid.

State the general equation that shows the reaction of an acid and a metal.

acid + metal ====> salt + hydrogen

Complete this sentence:


The more reactive the metal...

...the faster the rate of reaction.




Very reactive metals react explosively.

Why doesn't copper react with dilute acids?

It's less reactive than hydrogen.

How can the speed of reaction be indicated?

The rate at which the bubbles of hydrogen are given off.

What test confirms the presence of hydrogen?

Placing a burning splint where you believe the hydrogen to be. The infamous 'squeaky pop' will happen if hydrogen is present.

How can is a salt named?

Metal name (from the metal oxide, hydroxide or carbonate) + acid (with appropriate ending).

When sodium hydroxide reacts with HCl, what is the name of the salt formed?

Sodium chloride.

What's the name of the salt produced when the acid is:


a) Sulphuric acid


b) Citric acid


c) Nitric acid



a) sulphates


b) citrates


c) nitrates

What type of reaction produces nitrate salts?

A neutralisation reaction. In order to make a salt, nitric acid must be reacted with a base (it doesn't react well with metals, producing nitrogen oxides instead).

Fill the blanks:


Metals that are less ________ than ________ don't react with acid. Some metals (like sodium and potassium) are too ________ to mix with acid without causing a big explosion.

Metals that are less reactive than hydrogen don't react with acid. Some metals (like sodium and potassium) are too reactive to mix with acid without causing a big explosion.

Some metal oxides and metal hydroxides dissolve in water. What are these soluble compounds called?

Alkalis.

True or false?

Even bases that won't dissolve in water still react with acids.

True.




This means that all metal oxides and metal hydroxides react with acids to form a salt and water.

State the word equation for:


a) An acid reacting with a metal oxide


b) An acid reacting with a metal hydroxide

a) Acid + metal oxide ==> salt + water


b) Acid + metal hydroxide ==> salt + water




These are neutralisation reactions.

What can ammonia be neutralised with to make ammonium nitrate (a fertiliser)?

Nitric acid. Ammonia dissolves in water to make an alkaline solution. When it reacts with nitric acid, you get a neutral salt.

How is the neutralisation of ammonia different to other reactions?

No water is produced; it's just the salt.

Why is ammonium nitrate a good fertiliser?

It contains nitrogen from two sources; the ammonia and the nitric kind. Plants need both to make proteins.

When making a salt, why is it important to know whether or not it's soluble?

So you know which method to use.

Describe the process of making soluble salts using a metal or an insoluble base.

1) Choose the acid and the metal/insoluble base.


2) Add the metal/insoluble base - the solid will dissolve in the acid as it reacts. All the acid has been neutralised when the excess solid sinks to the bottom of the flask.


3) Filter out the excess metal/insoluble base to get the salt solution. To get pure, solid crystals of salt, evaporate some of the water (to make the solution more concentrated) and leave the rest to evaporate slowly.

What is the process called by which salt crystals are formed through evaporation of the liquid in a solution?

Crystallisation

What is meant by an 'insoluble base'?

A metal oxide or metal hydroxide, which are insoluble in water.

Describe the process of making soluble salts using an alkali.

1) Add exactly the right amount of alkali to neutralise the acid. Use an indicator to show when the reaction's finished.


2) Repeat this using exactly the same volumes of alkali and acid so the salt isn't contaminated with indicator.


3) Evaporate off the water to crystallise the salt.

Why can't you use the method described for making soluble salts using a metal/insoluble base with an alkali (soluble base)?

You can't tell when the reaction has finished and you can't just add an excess of acid and filter out what's left.

Describe the process of making insoluble salts using a precipitation reaction.

This is the method used for insoluble salts.


1) Pick two solutions that contain the ions you need. (To make lead chloride you need a solution which contains lead ions and one which contains chloride ions).


2) Mix these solutions together.


3) A precipitate of salt will form and once it separates out, filter it from the solution, wash it and then dry it on filter paper.

What else can precipitation reactions be used for?

They can be used to remove poisonous ions (like lead) from drinking water. Calcium and magnesium ions can also be removed from water this way - they make water 'hard' which stops soap from lathering properly.




Another use of precipitation reactions is in treating effluent (sewage) - unwanted ions can be removed.