Group 1, titration, bond energy calculations and energy profile diagrams

Question 1

what do you call the group 1 elements?

Answer 1

• alkali metals

Question 2

why do the group 1 elements have similar chemical properties?

Answer 2

• all have the same number of electrons in outer shell

Question 3

What is the reaction between the group 1 elements and water?

Answer 3

alkali metal + water -> metal hydroxide + hydrogen

Question 4

What is the pH of alkali metal solution and what colour would it turn the universal indicator?

Answer 4

• 13/14
• blue/ purple

Question 5

What is the pattern of the reactions of alkali metals with water?

Answer 5

• reactivity increases down group 1
• lithium floats, fizzes steadily and becomes smaller
• sodium floats, fizzes, melts and moves around on the surface
• potassium floats, fizzes vigorously, melts, moves around and catches fire (lilac flame)

Question 6

What is the pattern of the reactions of alkali metals with oxygen?

Answer 6

• burn vigorously with oxygen to form metal oxide
• lithium- red flame
• sodium- yellow flame
• potassium- lilac flame

Question 7

Why does reactivity increase down group 1?

Answer 7

• number of shells increase
• electrostatic attraction between nucleus + electron decrease
• easier to lose outermost electron

Question 8

What is the pattern of the reactions of group 1 with chlorine?

Answer 8

• react vigorously
• forms white metal chloride salt
• gets more vigorous down the group

Question 9

What colour compounds do group 1 form when reacting with non metals?

Answer 9

• white solids
• dissolves in water to form colourless compounds

Question 10

What are the properties of transition metals?

Answer 10

• high melting points (except mercury)
• high densities
• strong
• hard
• less reactive
• form coloured compounds
• used as catalysts
• conducts electricity

Question 11

What are the properties of the alkali metals?

Answer 11

• soft (can be cut with knife)
• low densities
• low melting points
• form white compounds

Question 12

How do you perform a titration?

Answer 12

1) rinse a flask, burette and pipette with deionised water
2) use a pipette and pipette filler to measure out exactly 25 cm^3 of sodium hydroxide solution and place it into the flask
3) place the flask on a white tile
4) add three or four drops of methyl orange indicator to the flask
5) place the burette in a clamp stand then fill it with dilute hydrochloric acid
6) open the tap of the burette so that the solution fills the gap below the tap
7) record the volume of the hydrochloric acid in the burette
8) add the hydrochloric acid to the flask, steadily at the first and then more slowly near the end point.
9) when the indicator changes colour, record the volume of aci added
10) repeat the experiment

Question 13

Explain the importance of the steps taken in a titration

Answer 13

• a white tile is placed -> see colour change more clearly
• same number drops of indicator every time -> if too much could affect volume of alkali + have a much deeper colour than it should’ve had
• make sure space below tap of burette is filled with solution -> could give false result (added more acid than you had)
• swirl the flask as the dilute acid is added -> make sure that all acid + alkali has reacted
• repeat the experiment -> to calculate an accurate mean
• add the hydrochloric acid slowly at first and drop by drop near the end point -> to ensure that you get the end point