Turn on thread page Beta

So say I was doing your bog-standard magnesium and HCl reaction... watch

    • Thread Starter
    Offline

    1
    ReputationRep:
    I'm measuring the temperature change of the HCl which would increase right? And what things apart from heat escaping to the environment and measuring errors could cause the result to not be quite right??
    • Community Assistant
    • Study Helper
    Offline

    17
    ReputationRep:
    Community Assistant
    Study Helper
    (Original post by XShmalX)
    I'm measuring the temperature change of the HCl which would increase right? And what things apart from heat escaping to the environment and measuring errors could cause the result to not be quite right??
    You are going to calculate the value of ΔH from the equation:

    ΔH = mcΔT

    and then divide by the number of moles reacted:

    ΔH/mol = mcΔT/mol

    so look for errors in every part of the equation..

    Heating up the thermometer
    Heating up the reaction vessel
    Evaporation
    Thermometer inaccuracy
    Volume inaccuracy (or mass of liquids)
    Hydrochloric acid/magnesium chloride solution SHC varying from that of water.
    Gas escaping with heat energy
    Mass of magnesium measured
    Concentration of the HCl
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by charco)
    You are going to calculate the value of ΔH from the equation:

    ΔH = mcΔT

    and then divide by the number of moles reacted:

    ΔH/mol = mcΔT/mol

    so look for errors in every part of the equation..

    Heating up the thermometer
    Heating up the reaction vessel
    Evaporation
    Thermometer inaccuracy
    Volume inaccuracy (or mass of liquids)
    Hydrochloric acid/magnesium chloride solution SHC varying from that of water.
    Gas escaping with heat energy
    Mass of magnesium measured
    Concentration of the HCl
    And its exothermic so ΔH for HCl would be negative whilst q would be positive right?
    • Thread Starter
    Offline

    1
    ReputationRep:
    Anyone?
    Offline

    11
    the magnesium may have a layer of oxide on it.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by domino0806)
    the magnesium may have a layer of oxide on it.
    Ahhh that a REALLY good one thanks!
    Does anyone know if its exothermic and if so if ΔH for HCl would be negative whilst q would be positive?
    • Thread Starter
    Offline

    1
    ReputationRep:
    Is it exothermic and if so if ΔH for HCl would be negative whilst q would be positive?
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 31, 2010
The home of Results and Clearing

1,647

people online now

1,567,000

students helped last year

University open days

  1. Bournemouth University
    Clearing Open Day Undergraduate
    Fri, 17 Aug '18
  2. University of Bolton
    Undergraduate Open Day Undergraduate
    Fri, 17 Aug '18
  3. Bishop Grosseteste University
    All Courses Undergraduate
    Fri, 17 Aug '18
Poll
Will you be tempted to trade up and get out of your firm offer on results day?

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.