Topic C4- Chemical changes Flashcards
(26 cards)
Which 4 metal are more reactive than hydrogen?
Gold,Silver,Platinum and Copper
What are two ways to measure the pH of a solution?
An indicator
A pH probe
What is the equation for neutralisation?
Acid+base -> salt+water
What is the symbol equation for neutralisation?
H+(aq) + OH-(aq) > H2O(I)
Do strong or weak acids ionise completely in water?
Strong
What is the factor H+ ion concentration changes by equal to?
10^-x
Is the pH of a strong acid always less than the pH of a weaker acid if they have the same concentration?
Yes
What is the difference with acid strength and acid concentration?
Acid strength- tells you what proportion of the acid molecules ionise in water
Acid concentration- how much acid there is in a certain volume of water
What does a more concentrated acid have?
A larger amount of acid there is in a certain volume of liquid
Will the pH decrease or increases with increasing acid concentration regardless of whether it’s a strong or weak acid?
Decrease
What is produced when acid+metal hydroxide/oxide react?
Acid+metal hydroxide/oxide -> salt+water
What is produced when acid+metal carbonate react?
Acid+metal carbonate -> salt+water+carbon dioxide
What are the 4 steps of crystallisation using an insoluble base?
1) pick the right acid and insoluble base (e.g. to get copper chloride mix hydrochloric acid and copper oxide)
2) warm the dilute acid using a bunsen burner, then turn it off. Add the insoluble base to the acid a bit at a time, until the base is in excess.
3) filter out the excess solid to get the salt solution.
4) heat the solution using a water bath to evaporate some of the water and then stop heating it and leave the solution to cool. Crystals can then be filtered and dried.
What is the reactivity series?
Please Send Lions, Cats, Monkeys & Cute Zebras Into Hot Countries
Potassium
Sodium
Lithium
Calcium
Magnesium
Carbon
Zinc
Iron
Hydrogen
Copper
What is produced when acid+metal react?
Acid+metal -> salt+hydrogen
What is produced when metal+water react?
Metal+water -> metal hydroxide+hydrogen
What 4 metals will all react with water?
Potassium
Sodium
Lithium
Calcium
What metals on the reaction series have to be extracted by electrolysis?
Higher than carbon
What metals in the reactivity series have to be extracted by reduction using carbon?
Below carbon
What is a loss and gain of electrons called?
Loss- oxidation
Gain- reduction
What will a more reactive metal displace?
A less reactive metal from its compound
Where will the positive and negative ions move towards in electrolysis?
The positive ions in the electrolyte will move towards the cathode and gain electrons
The negative iron in the electrolyte will move towards the anode and lose electrons
Why can molten ionic compounds be electrolysed?
Because the ions can move freely and conduct electricity
What is the 4 step process of electrolysis with aluminium?
1) Aluminium is extracted from the ore bauxite by electrolysis. Bauxite contains aluminium oxide.
2) Aluminium oxide has a very high melting temperature so it’s mixed with cryolite to lower the melting point.
3) The positive Al3+ ions are attracted to the negative electrode, where they each pick up three electrons and turn into neutral aluminium atoms. These then sink to the bottom of the electrolysis tank.
4) The negative O2- ions are attracted to the positive electrode where they each lose two electrons. The neutral oxygen atoms will then combine to form O2 molecules
