M3 Chapter 8 - Reactivity Trends WIP Flashcards
What is a reducing agent?
An element that itself is oxidised to reduce another species.
What is the most common type of reaction for group 2 elements?
Redox Reactions.
Group 2 Metal + Oxygen –> ?
Metal Oxide
Give an example of the previous reaction..
2Mg (s) + O2(g) –> 2MgO(s)
Prove that the previous reaction was a redox reaction.
Mg was oxidised to +2
O was reduced to -2
How do Group 2 Metals react with water?
Group 2 Metal + Water –> Alkaline Hydroxide + H2.
How does reactivity change down Group 2?
Reactivity increases down the group.
Metal + Acid –> ?
Salt + Hydrogen
What type of reaction is this?
Redox reaction.
How does reactivity change for this reaction?
Down group 2 the trend in reactivity remains the same. Therefore, the trend in reactivity remains increasing down the group.
Why is the trend of ionisation energy inversely proportional to the reactivity of group 2 elements?
The ionisation energies decrease down the group due to the attraction between the nucleus and outer electrons. Due to a similar reason, since reactions occur due to electrons, the ability for group 2 elements to lose electrons increases down the group therefore, these are inversely proportional.
Group 2 Oxide + Water –> ?
Metal Hydroxide
CaO + H2O –> ?
Ca2+ (aq) + 2OH-
Ca2+(aq) + 2OH - –> Ca(OH)2
Are these Metal Hydroxides soluble in water?
Yes they are soluble
How does solubility change for hydroxides down the group?
Down the group, solubility increases.
Down group 2, how does Solubility, pH and alkalinity change?
Down the group they all increase.
How would you test this trend for alkalinity?
- Add spatula of Group 2 oxides to water in a test tube.
- Shake mixture to ensure dissolvinf occurs.
- Measure the pH of each solution. The alkalinity will be seen to increase down the group.
How can Ca(OH)2 be used as bases? What functionality does it have?
Calcium Hydroxide = Used in agriculture to increase the pH of acidic soils. This is because the Ca(OH)2 reacts with protons (acids) to make Ca2+ and 2H2O.
How can Mg(OH)2 be used as bases? What functionality does it have?
The Mg(OH)2 can be used as antacids to treat indigestion. Calcium Carbonate can also be used to acheive the same. Mg(OH)2 + 2HCl –> MgCl2 + 2H2O.
