Chemistry

A 5.0-g Sample of KBr at 25.0 degrees celsius dissolves in 25.0 degrees celsius 25.0 mL of water also at 25.0 degrees celsius. The final equilibrium temperature of the resulting soltution is 18.1 degrees celsius. What is the enthalpy of of solution in kilojoules per mole of KBr?

asked by Sally
  1. Try reading your question. It needs to be cleaned up. It makes no sense as is.

    posted by DrBob222
  2. -q = dH ( dH = change in enthalpy Kj/mol)

    Use q=mc(Tf-Ti) and then convert to deltaH

    q=mc(Tf-Ti)

    q =?
    c= 4.814 J/g*C use specific heat of water since its in aqueous sol and we are not told differently

    m= total mass= mass KBr + mass water
    mass KBr= 5.0 g
    *mass of water from density =1g/mL so
    (25.0ml) (1g/ml)=25.0g water
    m = 25.0g water + 5.0 g KBr = 30.0g

    Tf-Ti= 18.1 - 25.0 = -6.9C

    q= (30g) (4.184 J/gC)(-6.9C)
    q= -1443 J

    -q = delta H kJ/mol KBr

    dH= (-q Joules)( 1 kJ/1000 Joules) / mol KBr

    *mol KBr = (5.0 g KBr)(1mol KBr) /119g KBr)= 0.042 mol KBr

    dH = -(-1443 J) (1kJ/1000J)/ 0.042 mol KBr)

    dH= 34.4 kJ/mol KBr

    posted by j

Respond to this Question

First Name

Your Response

Similar Questions

  1. Chemistry

    A 5.0-g Sample of KBr at 25.0 degrees celsius dissolves 25.0 mL of water also at 25.0 degrees celsius. The final equilibrium temperature of the resulting soltution is 18.1 degrees celsius. What is the enthalpy of of solution in
  2. Chemistry

    A 5.0g KBr sample, at 25 degrees celsius, dissolved in 25 ml of water, also at 25 degrees celsius. the final equilibrium temperature of the resulting solution is 18.1 degrees celsius, What is the enthalpy change in J/g and KJ/mole
  3. Chemistry

    A 100g sample of water at 90 degrees celsius is added to a 100g sample of water at 10 degrees celsius. The final temperature of the water is which of the following: a) between 50 degrees celsius and 90 degrees celsius b) 50
  4. Physics 20

    1. How much heat energy is required to change 500 grams of water at 100 degrees Celsius to steam at 100 degrees Celsius? 2. How much energy is lost if 7kg of water is cooled from 46 degrees Celsius to 2 degrees Celsius? 3. How
  5. Physics

    Please Help! I am having difficulties grasping these concepts. Explain please! 1. How much heat energy is required to change 500 grams of water at 100 degrees Celsius to steam at 100 degrees Celsius? 2. How much energy is lost if
  6. Physics

    The water from two buckets is mixed together. One bucket contains 5kg of water at 20 degrees Celsius and the other contains 1kg of water at 80 degrees Celsius. What is the final temperature of the mixture, assuming no heat is lost
  7. Chemistry

    A coffee-cup calorimeter initially contains 125 g water at 24.2 degrees celsius. Potassium bromide (10.5 g), also at 24.2 degree celsius, is added to the water, and after the KBr dissolves, the final temperature is 21.1 degrees
  8. Chemistry

    Calculate the joules of energy involved when 11 grams of water at 10.0 degrees Celsius cools and then freezes at 0.0 degrees Celsius. How many kilocalories are required to raise the temperature of 305 gtams silver from 30 degrees
  9. Chemistry

    A 50g sample of metal was heated to 100 degrees Celsius and then dropped into a beaker containing 50g of water at 25 degrees Celsius. If the specific heat of the metal is .25 cal/g degrees Celsius, what is the final temperature of
  10. PHYSICS 102E

    1. How much ice at -10 degrees Celsius is required to cool a mixture of 0.1 kg ethyl alcohol and 0.1 kg water from 20 degrees Celsius to 0 degrees Celsius? 2. Find the heat produced by 1 KW heating element in one hour. 3. A 3g

More Similar Questions