Last modified: Thu 07/28/2016 09:59:48 am
ACA

Oklahoma State University

It is OK to use your textbook or lecture notes from class, but if you can answers the questions without it that is OK too.

Do not press the RETURN or ENTER key while you are answering these questions. Your browser will interpret either the same as clicking on the Submit key.

Answer all of the questions below. If you do not know an answer enter CNA. However, it will help me the most if you answer each question with your best intuition/idea about what would be a reasonable answer.


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To answer the questions in the BCE we will use a new simulation currently being developed in collaboration with Pearson Publishing to perform a calorimetry experiment. In the simulation solid ionic compounds can be added to water and the change in temperature experienced when the solid ionic compound dissolves in water can be measured. By clicking on Calorimetry the simulation will be opened in a new tab.

In the simulation you will investigate how an amount of NaOH added to different amounts of water causes the temperature of the solution to change. After collecting the data you will be asked to make several predictions to determine your understanding of the important ideas we are learning about. In the data table below are the conditions (mass of NaOH and the volume of water needed for each experiment.) Using the simulation you will setup the conditions and measure the final temperature of the solution.)

If you have not already open the simulation. when the simulation opens an opening page will be displayed for a few seconds, and the screen wil automatically change to an Overview Page. You are welcome to read the Overview Page, and by clicking on the Learning Outcomes tab near the top of the display, you may read the Learning Outcomes Page. After reviewing these two pages click on the Experiment tab. When the screen changes the page will show two buttons: the Run Demonstration button and the Run Experiment button. You are welcome to click on the Run Demonstration button, but the instructions below are for the Run Experiment button.

After clicking on the Run Experiment button a new screen will appear with the experimental setup. A beaker and a calorimeter are shown on the screen. Beneath the beaker are three tabs (Liquids, Solids and Solutions). Click on the Solids tab, and then click on the popup list of solids and select NaOH. Use the slider to adjust the mass of NaOH that is appropriate for the Experiment you are performing. The temperature of the solid has already been set, click on the Next button on the left side of the screen to continue.

Next, add an amount of water to the calorimeter click on the popup menu below the calorimeter and select H2O as the liquid to be placed in the calorimeter. Add the amount of H2O that is appropriate for the experiment you are performing and set the initial temperature of the water in the calorimeter. Click the Next button when both those values are set.

Click on the Start button on the right side of the display to add the solid to the liquid in the calorimeter, and to mix the solid and liquid to form a solution. The digital thermometer on the calorimeter measures the temperature of the solution in the calorimeter as it is mixed.

1. Complete the table by setting up each of the experiments using the simulation, run the simulation and enter the final temperature. Calculate the T and enter in the table.

Exp #

Mass of NaOH (g)

Mass of H2O (g)

Initial T of H2O (°C)

Final Temp of solution(°C)

T (°C)

1

1.0

50

20

2

1.0

100

20

3

1.0

200

20

a) Is the solution process for NaOH exothermic or endothermic?

Provide evidence to support your claim.

b) What produces the heat in each of these experiments?

c) What absorbs the heat in each of these experiments?

Predictions:

Exp #

Mass of NaOH (g)

Mass of H2O (g)

Initial T of H2O (°C)

Final Temp of solution(°C)

T (°C)

4

2.0

100

20

5

2.0

400

20

2. Look at the microscopic view of any one of the experiments in the simulation and write the chemical equation that describes what happens when NaOH(s) is added to H2O.

3. Is there anything about the questions that you feel you do not understand? List your concerns/questions.

4. If there is one question you would like to have answered in lecture, what would that question be?