Acids Bases and Salts Flashcards by Anna Langdon

What is the name of the scale which decides which substances are acids and alkali?

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What number is neutral on the pH scale

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What side of the pH scale are alkalis?

Under 7

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What do acid solutions contain?

H+ ions

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What do alkali solutions contain?

OH- ions

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How is the concentration of ions measured?

mol/dm cubed

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What are H+ ions in

Water

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What concentration of OH- ions do strong alkalis have?

A high one - weak alkalis have a low one

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What degree of ionisation do strong acids and alkalis have?

A high one

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Why is hydrochloric acid a strong acid?

Because when the HCl molecules dissolve in the water almost all of the hydrogen atoms form H+ ions (ionisation)

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Why is ethanoic acid a weak acid?

Because only about 1% of the molecules form H+ ions

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What are the similarities in how strong and weak acids react

When they react with magnesium they both produce hydrogen gas
When they react with calcium carbonate they both produce carbon dioxide gas
In both these situations they produce the same volume of gas but the rate of reaction is faster for the strong acid

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What determines concentration of acids and alkalis

The amount and proportion of water present

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What volume of water do dilute acids have

A high one

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Why do some metals react with acids?

Because of their position on the reactivity series

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Recite the reactivity series (highest to lowest)

Potassium
Sodium
Calcium
Magnesium
Zinc
Iron
Tin
Lead
Copper
Silver
Gold

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How do metals at the top of the reactivity series react with acids?

Vigorously and exothermically even with dilute acids

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How do metals at the bottom of the reactivity series react with acids?

Not at all

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What is the general equation for metals reacting with acids?

Metal + acid = metal salt + hydrogen

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What kind of salts do hydrochloric acid and metals create?

Chlorides

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What is the equation for hydrochloric acid and a metal?

Metal + hydrochloric acid = magnesium chloride + hydrogen

What is the equation for sulfuric acid and a metal

Metal + sulphuric acid = metal sulfate + hydrogen

What kind of salts does sulfuric acid and a metal create?

A sulfate

What kind of salts do nitric acid and a metal create

A nitrate

What is the equation for a metal and nitric acid

Metal + nitric acid = metal nitrate + hydrogen

Define a neutralisation reaction

A chemical reaction happens if you mix together an acid and a base.

What do acids react with

Metal oxides, metal hydroxides, and metal carbonates

What are soluble bases called

Alkalis

What kind of reaction is one between an acid and a metal oxide

Exothermic (giving out heat)

What is the term for when acids react with bases or alkalis

A neutralisation reaction

How can neutralisation reactions involving acids and alkalis be characterised

HNO(3) + OH(-) = H(2)O

What is a base

A base is a substance that can neutralize the acid by reacting with hydrogen ions.

What do metal carbonates react with in a neutralisation reaction

They react with acids forming metal salts, water, and carbon dioxide gas

What is an example of a metal carbonate neutralisation reaction

Sulfuric acid + magnesium = magnesium + water + carbon dioxide

What is the test for a carbonate

To add an acid - if the substance effervesces (gives off bubbles) producing carbon dioxide gas, then it's a carbonate (or contains the carbonate ion)

What is a titration

A method of preparing solutions of solube salts, and a way of determining the relative and actual concentrations of solutions of acids or alkalis

What is an example of an indicator used in titration

Phenolphthalein

What happens during titration

- An indicator is added to a known volume of alkali - The acid is put into a burette - The concentration of either the acid or alkali has to be known - The acid is added to the alkali until the indicator changes colour

What is the equation we use to work out concentration during titration

Concentration of acid x volume of acid = concentration of alkali x volume of alkali

How do we test for a sulfate

By reacting a solution of the sulfate with a solution of barium chloride - a white precipitate of barium sulfate is formed

What is the symbol for a sulfate ion

SO(4)↑-2

What is an example of testing for a sulfate

Sodium sulfate + barium chloride = sodium chloride + barium sulfate

What kind of salt is barium sulphate

A solid insoluble salt

How can solid insoluble salts be prepared from precipitate solutions

By filtering the solution - the insoluble salt is trapped by the filter paper

What happens after the insoluble salt is separated

It is rinsed by distilled water

How can soluble salts be prepared

By reacting an acid with a metal base

What is an example of a solube salt

Magnesium sulfate

What is the result of mixing an acid and a metal base

A soluble salt, which has to be separated via evaporation

How is the excess insoluble base separated from the soluble salt?

Via filtration

How can we identify chemicals

By reacting known chemicals with them