posted by .

Hey can u guys help on this lab, I don't get it.

I have to figure out the: prediction, Analysis, and evaluation.

Problem: what is the molar enthalpy of ice?

mass of calorimeter: 3.76g
mass of calorimeter+ water: 103.26g
mass of calorimeter+ water+melted ice: 120.59g
initial temperature of ice:0.0 degress celcius
initial temperature of water:
32.4 degress celcius
final temp. of water: 15.6 degress celcius

The one thing I don't get is how to do the prediction and analysis. Can you help me figure out what the molar enthalpy of fusion of ice is? Thanks!

I assume you can calculate the mass of ice and mass of H2O from the data.
(massofice*deltaHfusion)+[massof ice*specificheatmeltedice*(Tf-Ti)]+[massofwater*specificheatwater*(Tf-Ti)]=0
Plug all those values in and solve for delta H fusion. If you have trouble, post your work to the point where you are stuck and we can help you through.

I didn't define my terms. Tf is the final temperature and Ti is the initial temperature of the appropriate material (meltice ice or water).

I got the answer -338.79J/mol, would that be right? And are the units right?

(17.33*deltaHfusion) + (17.33*4.19*(15.6-0)) + (99.5*4.19*-16.8) = 0

(17.33*deltaHfusion) + (-5871.2458)=0

(-5871.2458)/ (17.33)= deltaHfusion

-338.79J/mol =deltaHfusion


You have used 4.19 for the specific heat of water which has the units of J/g*C. The problem asks for the units per mole, not per gram. You may use your answer and multiply by the molar mass of H2O OR go back and substitute (I think it is 75.3 J/mol) for the 4.19 you used. I think I obtained about 6.08 kJ/mol or so and that is about what you have, too. My references list 4.184 and not 4.19 for the specific heat of water. At the least, I would use 4.18 and recalculate (then multiply by 18) or use 4.18 x 18.0 and get the answer in the units requested. I hope this helps.

I just looked at the problem you worked again and I think you have a sign wrong; i.e., you have 17.33X +(-5800something) = 0. When the 5800 something is carried to the other side it becomes a + number and the answer should be a positive number. And you added heat to the ice to melt it. At any rate, check your arithmetic and see if it doesn't come out a positive number. I meant to write that the first time and it slipped my mind.

THANK YOU! If I have any more questions I will ask.

oh i jus got it sry i am only in 8th..

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. Chemistrey

    Lab exercise 10C Calibrating bomb Calorimeter Before Molar specific enthalpies of reaction can be determined, a bomb calorimeter must be calibrated using primary standard of precisely known molar enthalpy. Complete the analysis of …
  2. CHEMISTRY-For Dr.Bob

    My chem class just finished a lab in which the objective was to find the percentage of silver and barium in a nitrate salt mixture by precipitating the chromates, separating out the precipitate from the solvent and spectator ions via …
  3. 12 Chemistry

    What is the molar enthalpy of combustion of magnesium?
  4. chemistry

    Find the false statement(s) about the thermochemistry experiment in which nitric acid is reacted with sodium hydroxide, and the enthalpy of the reaction is measured using an ice calorimeter. i. Regardless of which strong acid and strong …
  5. Chemistry

    The reaction between 0.045 g of calcium with an excess of water was carried out in an ice calorimeter as used in this lab. The volume of water in the calorimeter decreased by 0.18 mL during the reaction a) Write the equation for the …
  6. Chemistry

    Hey guys I did a lab and I have to answer the questions relating to the lab. I did question can someone please check if these are accurate 1. Calculation to Determine the molecular weight of unknown substance Mass of unknown used: …
  7. chemistry

    in a lab experiment to obtain the molar mass of a voltaile liquid, the following data is obtained: volume of flask=225ml mass of flask=77.834gms mass of flask+gas=78.416gms temperature=100 degrees celsius pressure=714 torr What is …
  8. Chemistry Lab

    In chemistry we are doing a lab that involves crucibles and Mg ribbon, we have three days to complete the lab. Anyways do you think it would be alright to substitute the mass of the crucible we had the first day with the mass of the …
  9. Chemistry

    A 1.76g sample of quinone, C6H4O2, is burned in a calorimeter whose total heat capacity is 7.854 kJ/C. The temperature of the calorimeter increases from 23.44 C to 29.14 C. What is the heat of combustion per mole of quinone?
  10. Chemistry

    I'm sorry But I'm still so badly stuck and I don't get it Initial mass of candle 40.3g Mass of tin calorimeter 41.1g Mass of half-filled calorimeter with water 220.4g Initial temp of water 18.8°C Final temp of water 26.6°C Final …

More Similar Questions