Turn on thread page Beta
    • Thread Starter
    Offline

    1
    ReputationRep:
    These questions may sound easy, but I haven't had a teacher for the past year! Could someone answer them please?

    - Suggest why only K (potassium) produces a flame? (When it reacts with water) (1 mark)

    - Potassium has a much lower density than most metals. Give another property of K that is different from most other metals. (1 mark)

    - What ideas about the electronic structure of atoms could be used to place K in the same group of metals as Na and Lithium? (2 marks)

    - How can Hydrogen Chloride be converted into Hydrochloric acid? (1 mark)

    - A central heating boiler burns methane at a rate of 1000g per hour. Calculate the maximum mass of CO2 produced by the boiler in 5 hours.
    (Mass numners: H:1; C:12; O:16) (4 marks)

    Thanks to anyone who answers this
    Offline

    14
    ReputationRep:
    (Original post by NickC)
    These questions may sound easy, but I haven't had a teacher for the past year! Could someone answer them please?

    - Suggest why only K (potassium) produces a flame? (When it reacts with water) (1 mark)

    - Potassium has a much lower density than most metals. Give another property of K that is different from most other metals. (1 mark)

    - What ideas about the electronic structure of atoms could be used to place K in the same group of metals as Na and Lithium? (2 marks)

    - How can Hydrogen Chloride be converted into Hydrochloric acid? (1 mark)

    - A central heating boiler burns methane at a rate of 1000g per hour. Calculate the maximum mass of CO2 produced by the boiler in 5 hours.
    (Mass numners: H:1; C:12; O:16) (4 marks)

    Thanks to anyone who answers this
    1. Well I presume you mean out of Li, Na and K, actually sometimes one sees a small flame with sodium, but nevermind. K is the most reactive out of the three listed, this is due to the fact that it's outermost electron is more weakly bound than in the other two alkali metals. The flame is cause by the fact that the reaction produces enough energy to ignite the hydrogen in the air as it is produced.

    2. Potassium is incredibly soft and can be cut easily with a knife at room temperature.

    3. K has a single s electron in it's outermost valence shell as does Na and Li.

    4. HCl (g) ----> HCl (aq) i.e. the most common way is to dissolve the HCl in water although any method where HCl can be ionised stabily will produce the acid.

    5. assuming that all the methane is converted to CO2 (this never happens in real life) then the reaction is.

    CH4(g) + 2 O2(g) ---> CO2 (g) + 2 H2O(g)

    Reaction is 1:1 CO2:CH4

    Mass CH4 = 16, moles/hr burnt = 1000 g / 16 gmol^-1 = 62.5 moles/hr

    therefore mass of CO2 (Mr = 44) produce per hour = 62.5 x 44 = 2750 g /hr

    x 5 = 13, 750 g = 13.75g
    • Thread Starter
    Offline

    1
    ReputationRep:
    Is 16 gmol^-1 the same as saying 16 grams per mole?
    Offline

    14
    ReputationRep:
    (Original post by NickC)
    Is 16 gmol^-1 the same as saying 16 grams per mole?
    yes, double check my calcs as I'm notorious at dropping numbers.
    • Thread Starter
    Offline

    1
    ReputationRep:
    Could u please explain this bit of the calculation:

    x 5 = 13, 750 g = 13.75g
    Offline

    14
    ReputationRep:
    (Original post by NickC)
    Could u please explain this bit of the calculation:

    x 5 = 13, 750 g = 13.75g
    Sorry that should be 13.75 kg not g. it's the amount of CO2 produced in 5 hours as the question asks for.
    • Thread Starter
    Offline

    1
    ReputationRep:
    OK, I get it now. thanks.
    Offline

    1
    ReputationRep:
    I thought most gp1 and some gp2 metals were also very soft.
    Offline

    14
    ReputationRep:
    (Original post by KP Nuts)
    I thought most gp1 and some gp2 metals were also very soft.
    But they are very much in the minority of metals.
 
 
 
Turn on thread page Beta
Updated: June 14, 2005
The home of Results and Clearing

2,595

people online now

1,567,000

students helped last year

University open days

  1. London Metropolitan University
    Undergraduate Open Day Undergraduate
    Sat, 18 Aug '18
  2. Edge Hill University
    All Faculties Undergraduate
    Sat, 18 Aug '18
  3. Bournemouth University
    Clearing Open Day Undergraduate
    Sat, 18 Aug '18
Poll
A-level students - how do you feel about your results?

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Write a reply...
Reply
Hide
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.