C5. Chemical Changes (Y10 - Summer 1) Flashcards
๐ข What sides of the pH scale are alkaline and acidic
The pH scale goes from 0 - 14.
The numbers from 6 - 0 are more acidic, while numbers from 8 - 14 are more alkaline
The pH of 7 is neutral.
๐ข What are Bases?
Bases are insoluable substances that are neutralised by acids, and they form a salt + water, and sometimes carbon dioxide.
Examples of bases are:
- Metal Oxides
- Metal Hydroxides
- Metal Carbonates
(ANYTHING THAT IS A CARBONATE IS DEFINITELY A BASE)
๐ข What are Alkalis?
Alkalis are substances on the upper end of the pH scale and release hydroxide ions in water OH- (aq).(Alkalis = Hydroxides that dissolve in water)
(ANYTHING THAT IS A HYDROXIDE IS DEFINITELY AN ALAKALI)
๐ข What are Acids?
Acids are substances on the lower side of the pH scale that are on that release hydrogen ions when added to water.
There are 2 types of acids, Strong Acids and Weak Acids
๐ข How are Strong and Weak Acids diffferent?
Strong acids release all hydrogen ions when added to water.
Weak acids only release some of the acid molecules release H+ ions in water.
๐ข Reactions of acids with bases:
- Acid + Metal Oxide โ>
- Acid + Metal Hydroxide โ>
- Acid + Metal Carbonate โ>
Acid + Metal Oxide โ> Salt + Water
Acid + Metal Hydroxide โ> Salt + Water
Acid + Metal Carbonate โ> Salt + Water + Carbon Dioxide
๐ข What is type of salt is made out of:
- Sulphuric Acid (H2SO4)
- Nitric Acid (HNO3)
- Hydrochloric Acid (HCl)
Sulphuric Acid (H2SO4): Sulphate
Nitric Acid (HNO3): Nitrate
Hydrochloric Acid (HCl): Chloride
๐ข Reactions of acids with alkalis:
- Metal + Acid โ>
- Alkali (Metal Hydroxides) + Acid โ>
- Carbonate + Acid โ>
- Base (Metal Oxides) + Acid โ>
- Metal + Acid โ> Salt + Hydrogen
- Alkali + Acid โ> Water + Salt
- Carbonate + Acid โ> Water + Carbon Dioxide + Salt
- Base + Acid โ> Water + Salt
- Remember*:
- MASH
- AAWS
- CAWCS
- BAWS
๐ข Strong Concentrated Acid:
- How much is dissolved
- Proportion of molecules that react with water to form H+ (aq)
- Example of Acid
- Typical pH
- Reaction with Magnesium
- Colour with Universal Indicator
How much is dissolved:
Lots
Proportion of molecules that react with water to form H+ (aq):
All
Example of Acid:
Hydrochloric Acid
Typical pH:
0 - 1
Reaction with Magnesium:
Vigourous Fizzing
Colour with Universal Indicator:
Red
๐ข Strong Dilute Acid:
- How much is dissolved
- Proportion of molecules that react with water to form H+ (aq)
- Example of Acid
- Typical pH
- Reaction with Magnesium
- Colour with Universal Indicator
How much is dissolved:
Not Much
Proportion of molecules that react with water to form H+ (aq):
All
Example of Acid:
Hydrochloric Acid
Typical pH:
2 - 3
Reaction with Magnesium:
Fizzing
Colour with Universal Indicator:
Red
๐ข Weak Concentrated Acid:
- How much is dissolved
- Proportion of molecules that react with water to form H+ (aq)
- Example of Acid
- Typical pH
- Reaction with Magnesium
- Colour with Universal Indicator
How much is dissolved:
Lots
Proportion of molecules that react with water to form H+ (aq):
Few
Example of Acid:
Ethanoic Acid
Typical pH:
4 - 5
Reaction with Magnesium:
Gentle Fizzing
Colour with Universal Indicator:
Orange
๐ข Weak Dilute Acid:
- How much is dissolved
- Proportion of molecules that react with water to form H+ (aq)
- Example of Acid
- Typical pH
- Reaction with Magnesium
- Colour with Universal Indicator
How much is dissolved:
Not Much
Proportion of molecules that react with water to form H+ (aq):
Few
Example of Acid:
Ethanoic Acid
Typical pH:
5 - 6
Reaction with Magnesium:
Hardly Any Fizzing
Colour with Universal Indicator:
Yellow
๐ข What salt is fromed from:
Iron + Hydrochloric Acid โ>
Hydrochloric Acid + Copper Carbonateโ>
Iron (II) Hydroxide + Sulphuric Acid โ>
Nitric Acid + Calcium Oxideโ>
(Give word equations and also chemical equations)
Iron + Hydrochloric Acid โ> Iron Chloride + Hydrogen
(Fe + 2HCl โ> FeCl2 + H2)
Hydrochloric Acid + Copper Carbonateโ> Water + Carbon Dioxide + Copper Chloride
(2HCl + CuCO3 โ> CuCl2 + H2O + CO2)
Iron (II) Hydroxide + Sulphuric Acid โ> Water + Iron (II) Sulphate
(Fe(OH)2 + H2SO4 โ> FeSO4 + 2H2O)
Nitric Acid + Calcium Oxideโ> Water + Calcium Nitrate
(2NHO3 + CaO โ> Ca(NO3)2 + H2O
๐ข What reactants form these salts:
___ + ___ โ> Zinc Sulfate + Water + Carbon Dioxide
___ + ___ โ> Magnesium Nitrate + Hydrogen
___ + Potassium Oxide โ> Potassium Chloride + ___
Calcium Hydroxide + ___ โ> Calcium Citrate + ___
Sulfuric Acid + Zinc Carbonate โ> Zinc Sulphate + Water + Carbon Dioxide
Magnesium + Nitric Acid โ> Magnesium Nitrate + Hydrogen
Hydrochloric Acid + Potassium Oxide โ> Potassium Chloride + Water
Calcium Hydroxide + Citric Acid โ> Calcium Citrate + Water
๐ข What is the Difference between Strong and Weak Acids
Strong acids completely ionise in aqueous solutions, while weak acids partially ionise in aqueous solution
๐ข What is the Ionic Equation for any acid with any alkali
H+ (aq) + OH- (aq) โ> H2O (l)
๐ข What are Examples and Formulas of 3 Strong Acids
Examples of Strong Acids are:
Hydrochloric Acid โ> Hydrogen + Chloride ions
(HCl(aq) โ> H^+(aq) + Cl^-(aq))
-Sulfuric Acid โ> Hydrogen + Sulphate Ions
(H2SO4(aq) โ> 2H^+(aq) + SO4 ^2- )
-Nitric Acid โ> Hydrogen + Nitrate Ions
(HNO3(aq) โ> H+(aq) + NO3-)
๐ข What are 3 Examples of Weak Acids
Examples of Weak Acids are:
-Ethanoic Acid โ Hydrogen + Acetate
(CH3COOH (aq) โ H+ + CH3COO-
- Citric Acid
- Carbonic Acid
๐ข What colour does Methyl Orange make:
- Strong Acids (lots of H+)
- Weak Acids (a few H+)
- Water (H+ = OH-)
- Weak Alkali (a few OH-)
- Strong Alkali (lots of OH-)
Strong Acids (lots of H+): Red
Weak Acids (a few H+): Pink
Water (H+ = OH-):
Orange
Weak Alkali (a few OH-): Yellow
Strong Alkali (lots of OH-): Yellow
๐ข What colour does Phenolphtalein Solution make:
- Strong Acids (lots of H+)
- Weak Acids (a few H+)
- Water (H+ = OH-)
- Weak Alkali (a few OH-)
- Strong Alkali (lots of OH-)
Strong Acids (lots of H+): Colourless
Weak Acids (a few H+): Colourless
Water (H+ = OH-):
Colourless
Weak Alkali (a few OH-): Pink
Strong Alkali (lots of OH-): Pink
๐ข What colour does Litmus Paper make:
- Strong Acids (lots of H+)
- Weak Acids (a few H+)
- Water (H+ = OH-)
- Weak Alkali (a few OH-)
- Strong Alkali (lots of OH-)
Strong Acids (lots of H+): Red
Weak Acids (a few H+): Red
Water (H+ = OH-):
Blue
Weak Alkali (a few OH-): Blue
Strong Alkali (lots of OH-): Blue
๐ข What colour does Universal Indicator Solution make:
- Strong Acids (lots of H+)
- Weak Acids (a few H+)
- Water (H+ = OH-)
- Weak Alkali (a few OH-)
- Strong Alkali (lots of OH-)
Strong Acids (lots of H+): Red - pH of 1
Weak Acids (a few H+): Orange - pH of 5
Water (H+ = OH-):
Green - pH of 7
Weak Alkali (a few OH-): Green - pH of 10
Strong Alkali (lots of OH-): Blue - pH of 14
๐ข What colour does Universal Indicator Paper make:
- Strong Acids (lots of H+)
- Weak Acids (a few H+)
- Water (H+ = OH-)
- Weak Alkali (a few OH-)
- Strong Alkali (lots of OH-)
Strong Acids (lots of H+): Red - pH of 1
Weak Acids (a few H+): Orange - pH of 5
Water (H+ = OH-):
Green - pH of 7
Weak Alkali (a few OH-): Green - pH of 10
Strong Alkali (lots of OH-): Blue - pH of 14
๐ข What is the pH scale, and How does it show Relative Acidity?
pH is a measure if the concentration if H+ ions in solution.
The pH scale is logarthmic, meaning that each change of 1 on the scale represented a change in concentration by a factor of 10.
-For two acids of equal concentration, where one is strong and the other is weak, then the strong acid will have a lower pH due to its capacity to dissociate more and hence put more H+ ions into solution than the weak acid.
๐ข What is a Redox Reaction
Redox reactions are reactions where both oxidation and reduction are taking place.
Displacement reactions are examples of redox reactions as one species is being oxidised (losing electrons) while the other is being reduced (gaining electrons).
For example, if magnesium was added to copper sulphate solution, the magnesium metal would be oxidised, while the copper ions were being reduced.
๐ข What is Oxidisation?
Oxidisation:
Oxidation is the loss of electrons by a reactant.
When a metal element is reacting to form a compound then it is being oxidised.
For example:
Mg(s) + O2(g) โ MgO(s)
The metal atoms are losing electrons to form an ion. They are being oxidised.
Mg(s) โ Mg2+(aq) + 2eโ
This is known as an ion-electron equation.
๐ข What is Reduction?
Reduction:
Reduction is the opposite of oxidation. It is the gain of electrons.
Compounds reacting that result in metal elements being formed are examples of reduction reactions.
For example:
Cu2+(aq) + 2eโ โ Cu(s)
The metal ions are gaining electrons to form atoms of the element. They are being reduced.