Last modified: Thu 09/21/2017 09:58:18 pm
BCE

Oklahoma State University

It is OK to use your textbook, 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.


First Name:

Last Name:

School:

In this BCE you will investigate the conductivity behavior of a set of substances. Use the table below to obtain the three substances whose conductivity you are to measure based on the last digit in your OSU Student Identification Number.

Last Digit of your OSU Student ID #

Substance 1 (Salt)

Substance 2 (Acid)

Substance 3 (Base)

0

NaCl

HCl

NH3

1

NH4NO3

H2SO4

HONH2

2

NH4Cl

HC2H3O2

NaOH

3

NaC2H3O3

HF

Ca(OH)2

4

Na2SO4

HC3H5O3

NaOH

5

NaCN

HNO3

(CH3)2NH

6

NaNO3

HClO2

Ca(OH)2

7

NaF

HNO2

C6H5NH2

8

(NH4)2SO4

HCl

(CH3)2NH

9

NaCN

HNO3

NH3

Open the Flash animation using the link below and test the conductivity of your three substances. You are welcome to test the conductivity of other substances, but I specifically want the results of your three substances. For each test you are to use approximately the same volume (within a milliliter or two). You are to observe the brightness of the bulb. The bulb brightness is a measure of the number of ions in solution. Use a scale from 1 (no intensity) to 5 (very bright) to indicate the level of brightness for your measurement. You might want to check a few other compounds to see what the different brightness levels there are. Record your results in Q1 below.

Here is the link to the Flash animation

(The movie will open in another window, to return to the BCE either close the Flash movie window or re-adjust its size and move it aside to get to the BCE window behind and answer the questions.)

1. Complete the table below;

Substance (formula)

Brightness Value (1 - 5)

#1 (salt)

#2 (acid)

#3 (base)

2. An electrolyte is a substance that produces ions when added to water (Check the video on Strong electrolytes in Chapter 4under the Video tab in the ebook in the library on the class Connect Web Site in the online textbook or Figure 4.3 in your textbook.) The presence of ions in the solution is what allows charge to flow in the solution. The intensity of the light is a measure of amount of ions in the solution (NOTE: 5 is very bright and 1 would be no brightness). There are three types of electrolytes: strong, weak and non. Identify which type of electrolyte each of your three substances are.

Substance

Electrolyte (strong/weak/non)

#1 (salt)

#2 (acid)

#3 (base)

3. For each of your substances identify the cation and anion present in solution. You may need to refresh your memory of some of the common cations and anions listed in the tables in Chapter 2 of your textbook. Check Table 2.3 - 2.5 in your textbook. (NOTE: Remember the cation has a charge and so does the anion. The correct charge is as important as the correct formula, so do not forget to include the charge. For cations like Na+, enter the ion in the cell below as Na^+. For anions like CO32-, enter the ion in the cell below as CO3^2-.)

Substance

Cation

Anion

#1 (salt)

#2 (acid)

#3 (base)

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

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