chemical changes Flashcards
What is produced when an acid and metal react?
Salt and hydrogen.
What is a redox reaction?
When one substance is reduced and another substance is oxidised.
Which 2 non metals are often included in the reactivity series?
Carbon and hydrogen.
What colour flame does potassium produce?
Lilac
What colour flame does sodium produce?
Yellow.
What colour flame does lithium produce?
Red.
What colour flame does calcium produce?
Orange/Red.
What is displacement?
When a more reactive element displaces a less reactive element from a compound.
What is oxidation?
When oxygen gains electrons and fills its outer shell from another element that loses its outer shell and electrons.
What is reduction?
Gaining electrons but losing oxygen or gaining hydrogen.
What do an acid + a base produce?
Salt + water
Acids are neutralised by metal carbonates to produce…
Salt, water and carbon dioxide.
What salts does hydrochloric acid produce?
Chlorides.
What salts does nitric acid produce?
Nitrates.
What salts does sulfuric acid produce?
Sulfates.
What do acids produce in aqueous solutions?
H+ ions.
What do alkalis produce in aqueous solutions?
OH- ions.
What happens to a strong acid in an aqueous solution?
It is completely ionised.
What happens to a weak acid in an aqueous solution?
It is partially ionised.
Which elements in the reactivity series react with water?
Potassium, sodium, lithium and calcium.
What elements in the reactivity series react with dilute acid?
Calcium, magnesium, zinc, iron and copper.
Gold is very unreactive since…
It is found in the earth as the metal itself.
What do metal compounds require to extract the metal?
Chemical reactions.
Metals less reactive than carbon can be extracted from their oxides by…
Reduction with carbon.
What are soluble salts made from?
Acids by reacting them with solid insoluble substances.
What do you fill the burette with in the titration practical?
100cm cubed of acid.
What do you use a pipette for during the titration practical?
To add 25cm cubes of alkali to the conical flask.
What is a titre?
The volume of acid needed to exactly neutralise.
What are the 4 steps for working out concentration?
- Convert volumes into dm cubed
- Work out moles
- Work out the molar ratio
- Work out the concentration
When an ionic substance is melted or dissolved, ions are…
Free to move.
Passing a current through substances that are a solution or molten means…
The substance can be broken down into elements. (electrolysis)
What is the name for the substance being broken down in electrolysis?
The electrolyte.
What is produced when ions are discharged at the electrodes?
Elements.
In electrolysis, positively charged ions move to…
The negative electrode (cathode).
In electrolysis, negatively charged ions move to…
The positive electrode (anode).
What is the ionic equation at the negative electrode?
X+ + e- —> X and electrons are gained so positive ions are reduced.
What is the ionic equation at the positive electrode?
X- —> e- + X and electrons are lost so negative ions are oxidised.
