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Estimating specific heat and molecular weight from enthalpy

Could you please take a look at this? I'm having trouble with #2 and #3. Thank you!


#1 - Initial temperature of Iron shot (Fe) metal: 100°C
Final temperature of Iron shot (Fe) metal: 28°C
Initial temperature of water from calorimeter: 20°C
Final water temperature from calorimeter: 28°C

#2 - Estimate of specific heat for metal:
(use 1 cal/gm-°C for water)

#3 - Estimate the atomic weight of Iron shot (Fe) metal:


Step 1: Obtain metal sample in test tube. First add a test tube to the Lab. Add 100 gm of Iron Shot (Fe). Add a thermometer to the test tube so that you can record the initial temperature of the Fe.

Step 2: Prepare hot water bath and add test tube with metal. Obtain a 250 ml beaker. Add 150ml of water at room temperature to the beaker. Place test tube within beaker. Now heat the combined beaker test tube arrangement by heating with a bunsen burner until the Fe shot reaches the boiling point of water 100 °C.

Step 3: Place heated metal in calorimeter with water at room temp. Add Calorimeter to Lab. Add 100 ml of water at room temp 20 °C to calorimeter. Remove test tube from beaker. Pour the heated Iron into the calorimeter and close the calorimeter. Record the final temperature of the water.

Solution Preview

So for #2 we want to find the specific heat, which as you recall was the "c" in q=mcdT.

We know the m of Fe is 100g. The initial T is 100 degrees, and the final T is 28 degrees.

The initial temp of the water was 20 degrees, and the final was 28. 150 mL of water is 150g ...

Solution Summary

How do we find the molecular weight of a substance and its specific heat if we know some data about its enthalpy? In this solution we explore, step-by-step, the math involved in solving these types of problems!