C5 - Chemical changes 1️⃣✅ Flashcards
What is the mneumonic to remeber the order of the reactivity series?
P ossums
S ometimes
L ick
C ats
M ichael
C an’t
Z ipline
I nto
H is
C ar
Using the mneumonic for the reactivity series, list the reactivity series in order.
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
- Carbon
- Zinc
- Iron
- Hydrogen
- Copper
What elements are less reactive than carbon?
- Zinc
- Iron
- Hydrogen (non metal)
- Copper
What elements are more reactive than carbon?
- Potassium
- Sodium
- Lithium
- Calcium
- Magnesium
What is a displacement reaction?
A displacement reaction occurs when a more reactive element displaces, or pushes out, a less reactive element from a compound that contains the less reactive element
What is oxidation?
Oxidation is the loss of electrons from a substance whilst also being the gain of oxgyen by a substance.
What is reduction?
Reduction is the gain of electrons by a substance whilst also being the loss of oxygen by a substance
What is a redox reaction?
When oxidation and reduction take place at the same time (red – reduction, ox – oxidation)
What is an oxidising agent?
The chemical that causes oxidation by providing oxygen
What is a reducing agent?
The chemical that causes the other chemical to be reudced by removing oxygen
What happens when metal reacts with oxygen?
A metal oxide is produced
What is pH?
A measure of how acidic and how alkaline a solution is
What do low numbers represent on the pH scale?
Most acidic
What do high numbers represent on the pH scale?
Most alkaline
What is the pH of something that is neutral?
7
What is an acid?
Any substance that forms an aqueous solution with a pH less than 7
What is a base?
Any substance with a pH greater than 7
What is an alkali?
A base that dissolves in water to form a solution with a pH greater than 7
What happens when you react an acid and a base together?
A neutralisation reaction
What will a neutrilisation reaction always produce?
A salt and water
What is a commonly used acid?
Hydrochloric acid (HCl)
What is a commonly used base?
Sodium hydroxide (NaOH)
What ions do acids produce?
H+
What ions do bases produce?
OH-
What is a strong acid?
Acids that completely ionise into H+ ions e.g. 100% of the acid particles will split up/ disacociate
What is a weak acid?
Acids that do not completely ionise into H+ ions e.g. less than 100% split/ disasociate
Explain why at any given concentration a strong acid has a lower pH than a weak acid.
As all molocules in a strong acid disasociate and produce H+ ions and only a few molocules in weak acids disasociate to produce H+ ions, regardless of the concentration of strong/ weak acid, there will always be more H+ ions present in a concentration of a strong acid, consequently leaving it with a low pH (as the more H+ ions, the lower the pH)
What is the relationship between the concentration of H+ ions and pH?
As the number of H+ ions increases the pH decreases, labelling the solution as acidic
Describe how you would produce a soluble salt (pure, dry crystals) from a dilute aicd and an insoluable base
- place dilute acid into a beaker and gently heat it whilst slowing adding some of the insoluble base (base will initially react and disappear into acid but once it stops disappearing and remains in solution, the acid has been neutralised and the base in in excess)
- Next filter out excess insoluble base using filter paper and filter funnel, leaving behind the dissolved form of the soluble salt.
- After that you would heat up the solution using a water bath or electric heater to evapourate some solution until some of solution has evapourated and crysals start to form take it out and leave it to cool which will cause more crystyals to form
- Finally filter out your crystals from remaining solution and pat dry with filter paper
List 3 common types of insoluable bases you could be asked to react with an acid to form soluble salts?
(metal ________)
metal hydroxide
metal oxide
metal carbonate
Which products are formed when an acid reacts with a metal oxide?
Salt & water
During a neutralisation reaction, the positive ____________ ions from the acid react with the negative ____________ ions from the alkali to form molecules of water.
During a neutralisation reaction, the positive hydrogen ions from the acid react with the negative hydroxide ions from the alkali to form molecules of water.
Which products are formed when an acid reacts with a metal hydroxide?
Salt & water
What products are formed when hydrochloric acid reacts with potassium hydroxide?
Potassium chloride (salt) and water
Which products are formed when an acid reacts with a metal carbonate?
Salt, water and carbon dioxide
Lithium carbonate and hydrochloric acid undergo a neutralisation reaction. What salt would be produced?
Lithium Chloride
To work out the formula of the salt, take the ____________ ion from the base, such as sodium from sodium oxide (Na2O), and the ____________ ion from the acid, such as chloride from hydrochloric acid (HCl), and ________________________. So in this case of sodium hydroxide reacting with hydrochloric acid the salt would be ____________ (____)
To work out the formula of the salt, take the positive ion from the base, such as sodium from sodium oxide (Na2O), and the negative ion from the acid, such as chloride from hydrochloric acid (HCl), and combine them together. So in this case of sodium hydroxide reacting with hydrochloric acid the salt would be Sodium Chloride (NaCl)
How does Potassium, Sodium, Lithium & Calcium react when in water?
Fizz giving off hydrogen gas and produce alkaline metal hydroxide
How does Potassium, Sodium and Lithium react with a dilute acid?
They explode
How does Calcium react with a dilute acid?
Fizz giving off hydrogen gas and form a salt
How does Magnesium, Aluminium, Zinc and Iron react with a dilute acid?
Fizz giving off hydrogen gas and form a slat
How does Magnesium, Aluminium, Zinc and Iron react with water?
Very slowly
How do you extract metals from oxides/ ores that are less reactive than carbon?
By reduction with carbon
How does reduction with carbon work?
Metal oxides that are less reactive than carbon can be be extracted easily by reacting them with carbon in order to undergo a displacement reaction where the metal from the metal oxide is displaced by tue carbon to leave behind the pure metal and carbon dioxide
