C5.7 - Neutralisation and the pH scale Flashcards
What do you do when you dissolve a substance in water?
When you dissolve a substance in water, you make an aqueous solution
When you dissolve a substance in water, you make an aqueous solution, as what happens with what?
When you dissolve a substance in water, you make an aqueous solution, as what happens with the washing powder in a washing machine
When you dissolve a substance in water, you make an aqueous solution.
What does whether the solution formed is acidic, alkaline or neutral depend on?
Whether the solution formed is: 1. Acidic 2. Alkaline Or, 3. Neutral depends on which substance you have dissolved
A solution of washing powder is what?
A solution of washing powder is slightly alkaline
Alkalis
Alkalis are soluble hydroxides
Example of an alkali solution
An example of an alkali solution is sodium hydroxide solution
Bases
Bases are:
- Substances that can neutralise acids
- Proton (H+ ion) acceptors
Examples of bases
Examples of bases are:
- Iron oxide
- Copper hydroxide
Examples of bases include iron oxide and copper hydroxide.
What are they both?
- Iron oxide
- Copper hydroxide
are both insoluble in water
Acids
Acids are proton (H+ ion) donors
Examples of acids
Examples of acids are:
- Citric acid
- Sulfuric acid
- Ethanoic acid
How do all acids taste?
All acids taste very sour
All acids taste very sour, although many acids are far too dangerous to put in your mouth.
What acids are weak enough to be edible?
- Ethanoic acid
- Citric acid
are acids that are weak enough to be edible
Where is ethanoic acid found?
Ethanoic acid is found in vinegar
Where is citric acid found?
Citric acid is found in:
- Citrus fruit
- Fizzy drinks
Neutral
Neutral is:
- A solution with a pH value of 7, which is neither acidic or alkaline
- Something that carries no overall electrical charge
What is pure water?
Pure water is:
- Neutral
- Neither acidic or alkaline
Where are acids and bases?
Acids and bases are:
- All around you
- In many of the things used in everyday life
- In your bodies, too
How is hydrochloric acid formed?
Hydrochloric acid is formed when the gas hydrogen chloride, HCl, dissolves in water:
water
HCl (g) —> H+ (aq) + Cl- (aq)
What do all acids do when added to water?
All acids release H+ (aq) ions into solution when added to water
All acids release H+ (aq) ions into solution when added to water.
What makes a solution acidic?
It is these excess H+ (aq) ions that make a solution acidic
Why are alkalis the bases often used in experiments?
Alkalis are the bases often used in experiments, because alkalis are bases that:
- Dissolve in water
- Form solutions
Alkalis are the bases often used in experiments, because alkalis are bases that dissolve in water and form solutions.
What is often found in school labs?
Sodium hydroxide solution is often found in school labs
When do you get sodium hydroxide solution?
You get sodium hydroxide solution when you dissolve solid sodium hydroxide in water:
water
NaOH (s) —> Na+ (aq) + OH- (aq)
What do all alkalis form when added to water?
All alkalis form aqueous hydroxide ions when added to water
All alkalis form aqueous hydroxide ions when added to water.
The chemical formula for aqueous hydroxide ions
The chemical formula for aqueous hydroxide ions is OH- (aq)
All alkalis form aqueous hydroxide ions when added to water.
What make a solution alkaline?
It is these excess aqueous hydroxide ions, OH- (aq), that make a solution alkaline
Indicators
Indicators are substances which change colour when you add them to:
- Acids
- Alkalis
Indicators are substances which change colour when you add them to acids and alkalis.
Litmus
Litmus is a well-known indicator:
- Red in acid
- Blue in alkali
What can you use to show how acidic or alkaline a solution?
You use the pH scale to show how: 1. Acidic Or, 2. Alkaline a solution is
pH
pH is a number which shows how strongly: 1. Acidic Or, 2. Alkaline a solution is
You use the pH scale to show how acidic or alkaline a solution is.
Where does the scale run from?
The scale runs from:
1. 0 (most acidic)
to
2. 14 (most alkaline)
You use the pH scale to show how acidic or alkaline a solution is.
The scale runs from 0 (most acidic) to 14 (most alkaline).
What can you use to find the pH of a solution?
You can use universal indicator to find the pH of a solution
You can use universal indicator to find the pH of a solution.
What is universal indicator?
Universal indicator is a special indicator made from a number of dyes
What is anything in the middle of the pH scale?
Anything in the middle of the pH scale (pH 7) is neutral, neither:
1. Acidic
Or,
2. Alkaline
You use the pH scale to show how acidic or alkaline a solution is.
You can also use a what?
You can also use a pH meter
You use the pH scale to show how acidic or alkaline a solution is.
You can also use a pH meter, which has a glass probe attached to dip in the solution being tested.
What do some electronic pH sensors do?
Some electronic pH sensors give a digital display of the pH directly
What can pH probes or sensors do?
pH probes or sensors can measure pH values accurately
Example of a substance that has a pH value of 1
An example of a substance that has a pH value of 1 is hydrochloric acid
Example of a substance that has a pH value of 2
An example of a substance that has a pH value of 2 is lemon juice
Examples of substances that have a pH value of 3
Examples of substances that have a pH value of 3 are:
- Orange juice
- Vinegar
Example of a substance that has a pH value of 5
An example of a substance that has a pH value of 5 is black coffee
Example of a substance that has a pH value of 6
An example of a substance that has a pH value of 6 is rainwater
Example of a substance that has a pH value of 7
An example of a substance that has a pH value of 7 is pure water
Example of a substance that has a pH value of 8
An example of a substance that has a pH value of 8 is baking soda
Examples of substances that have a pH value of 9
Examples of substances that have a pH value of 9 are:
- Milk of magnesia
- Soap
Example of a substance that has a pH value of 12
An example of a substance that has a pH value of 12 is washing soda
Examples of substances that have a pH value of 14
Examples of substances that have a pH value of 14 are:
- Oven cleaner
- Sodium hydroxide
Alkalis are soluble hydroxides.
Their solutions are have a pH value of what?
Their solutions are have a pH value of more than 7
Alkalis are soluble hydroxides.
Their solutions are have a pH value of more than 7, so what?
Their solutions are have a pH value of more than 7, so their solutions are alkaline
Bases are substances that can neutralise acids and are proton (H+ ion) acceptors.
They are the what of a metal that will react with an acid?
Bases are the: 1. Oxide 2. Hydroxide Or, 3. Carbonate of a metal that will react with an acid
Bases are substances that can neutralise acids and are proton (H+ ion) acceptors.
They are the oxide, hydroxide or carbonate of a metal that will react with an acid, forming what?
Bases are the: 1. Oxide 2. Hydroxide Or, 3. Carbonate of a metal that will react with an acid, forming a salt as 1 of the products
Bases are substances that can neutralise acids and are proton (H+ ion) acceptors.
They are the oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as 1 of the products.
Bases include what?
Bases include alkalis
When acids are dissolved in water, its solution has a pH value of what?
When acids are dissolved in water, its solution has a pH value of less than 7
All acids taste very sour, although many acids are what?
All acids taste very sour, although many acids are far too dangerous to put in your mouth
Indicators are substances which change colour when you add them to acids and alkalis.
Litmus is a well-known indicator, red in acid and blue in alkali, but what?
Litmus is a well-known indicator:
1. Red in acid
2. Blue in alkali
,but there are many more
You can use universal indicator to find the pH of a solution.
Universal indicator is a special indicator made from a number of dyes.
What does it do, as the pH changes?
Universal indicator turns a range of colours as the pH changes
You use the pH scale to show how acidic or alkaline a solution is.
You can also use a pH meter, which has a what?
You can also use a pH meter, which has a glass probe attached to dip in the solution being tested
You use the pH scale to show how acidic or alkaline a solution is.
You can also use a pH meter, which has a glass probe attached to dip in the solution being tested.
Some electronic pH sensors give a digital display of the pH directly.
Others can be what to monitor and record pH changes over time?
Others can be attached to data-loggers and computers to:
1. Monitor
2. Record
pH changes over time