Topic Test 2 Revision Flashcards
pH
A measure of how acidic or alkaline a solution is
pH scale
0-14
A low number on the pH scale is…
Acidic
A high number on the pH scale is….
Alkaline
What pH are neutral substances
7
What is the pH of pure water?
7
What is an indicator?
Chemical dyes that change colour at different pH levels
What is the name of the most common indicator?
Universal Indicator
If a substance is extremely acidic, what colour would the universal indicator show?
Red
What colour would a universal indicator go if a substance is neutral?
Green
What colour would a universal indicator go if a substance is very alkaline?
Purple
Two ways to measure pH
- Indicator
- pH probe
What is the benefit of using a pH probe in comparison to an indicator?
Is more accurate and precise as it does not involve human judgement.
What is an acid?
Any substance that forms an aqueous solution with a pH of less than 7
Why are acids an aqueous solution?
They release hydrogen ions in water which makes the solution acidic
What is a base?
Any substance with a pH greater than 7
Alkalis are a subgroup of ________
Bases
What makes a base an alkali?
Soluble in water
What happens when we react an acid and a base together?
We get a neutralization reaction
What does a neutralization reaction produce?
Salt and water
Hydroxide
HCI
HCI
Hydroxide
Sulfuric acid
H2SO4
H2SO4
Sulfuric acid
Nitric acid
HNO3
HNO3
Nitric acid
Sodium Hydroxide
NaOH
NaOH
Sodium Hydroxide
Calcium Carbonate
CaCO3
CaCO3
Calcium Carbonate
What do strong acids have in common?
The ionise completely
What does it mean to ionise completely?
The reactants turn completely into products.
What do weak acids have in common?
They don’t fully ionise
The ionisation of a weak acid is ______________
reversable
What is the strength of an acid
How much an acid DISSOCIATES
What is the concentration of an acid?
How much acid there is in a certain volume
As the concentration of Hydrogen ions gets a higher, the pH gets ________
Lower
Each decrease of one on the pH scale represents Hydrogen ions ________________________
Increasing by a factor of 10
If we moved from pH 5 to pH 3 the number of Hydrogen ions will _____________________________
increase x100
If we moved to pH 8 to pH 11 the number of Hydrogen ions will _____________________________
decrease x1000
A substance with a low pH will have a _____________ concentration of Hydrogen ions
high
At any given concentration, a strong acid will always have a _____pH in comparison to a weak acid
lower
Metal Oxide + Acid =
Salt + water
Metal hydroxides + Acids =
Salt + water
HCl + Na2O =
2NaCl + H2O
H2SO4 + 2KOH =
K2SO4 + 2H2O
Acid + Metal carbonate =
Salt + water + CO2
2HNO3 + CaCO3 =
Ca (NO)3 + H2O + CO2
3 characteristics of bases
- Slippery to touch
- Bitter to taste
- pH of above 7
What do bases do to red litmus paper?
Turn it blue
3 characteristics of acids
- Burn skin
- Taste sour
- Have a pH of below 7
What do acids do to blue litmus paper?
Turn it red
What is the study of organic chemistry?
About compounds that contain Carbon
Each atom of Carbon can form ___________ bonds
4
What is a Hydrocarbon?
Any compound formed from Carbon and Hydrogen only
What is the general formula for Alkanes?
Cn + H2n + 2