Activity 3C: Graphing as a Means a Seeking Relationships



CHEMISTRY 11:

Graphing as a Means a Seeking Relationships Name:____________

Purpose:

• To determine the mathematical relationship between mass and volume by measuring 3 liquids accurately and precisely, then analyzing the data using graphing techniques.

Materials:

• 3 Reagent Stations - burets with different liquids:

1) water

2) methanol, and

3) sodium chloride solution

• Centigram balance, clean erlenmeyer flask, graph paper, and calculator.

[pic]

buret

Procedure:

*Wear a lab apron, and safety goggles for this activity. Methanol is both flammable and toxic, so open the Windows! *

*Absolutley NO horse-play!*

1) Your group will be assigned a volume of liquid that you are to measure.

Use this same volume for all three solutions.

2) Determine and record the mass of a clean erlenmeyer. It is important that you use

the same erlenmeyer throughout this experiment, since different erlenmeyers can

have different masses, even though they appear to be identical.

3) Go to one of the burets that contains either

i) water

ii) methanol, or

iii) sodium chloride solution

(the order is not important), and dispense your assigned volume into your erlenmeyer

as accurately as possible. Do not be concerned, if you do not obtain precisely your

assigned volume. What is important, is that you accurately record the volume you

do obtain in the appropriate Data Table. (next section)

4) Measure the total mass of the liquid and the erlenmeyer. (Subtract the previous mass of the erlenmeyer in order to determine the mass of the liquid.)

5) Do NOT empty the flask! Now, repeat Procedure Steps 2 and 3 for the other

two liquids. Each time you add a different liquid, do NOT empty the flask, just

keep determining the mass of each volume by subtracting the previous reading

balance reading.

6) All groups need to share their data with the class.

7) Pour any leftover liquid into the designated waste container.

8) Clean up your area thoroughly and wash your hands.

Data (Use the correct number of significant figures!!)

A: Individual Group Results:

Table 1: Mass of Water, Salt Water, and Methanol

|Contents of Buret |Mass of Erlenmeyer |Mass of Erlenmeyer + Liquid |Mass of Liquid |

| |(grams) |(grams) |(grams) |

|Water | | | |

|Salt Water | | | |

|Methanol | | | |

Table 2: Volume of Water, Salt Water, and Methanol

|Contents of Buret |Final (mL) |Initial (mL) |Volume (mL) |

|Water | | | |

|Salt Water | | | |

|Methanol | | | |

B: Class Results:

Table 3: Mass and Volume of Water, Salt Water, and Methanol

|Contents of Buret | | | |

| |Water |Salt Water |Methanol |

| |Volume |Mass |Volume |Mass |Volume |Mass |

|Group |(mL) |(grams) |(mL) x-x- axis |(grams) |(mL) |(grams) |

| |x-axis |y-axis | |y-axis |x-axis |y-axis |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

| | | | | | | |

Analysis of Data (Graphing):

1) Plot 3 graphs on 1 sheet of graph paper. (Plot the mass (y-axis) of each liquid

verses its volume (x-axis).)

2) Include the following information:

- axes (outlined in pen) - scale

- title - labels on each axis with variable and units

- plots (in pencil) - 3 best fit lines (NOT dot-dot)(different colors), and

- a legend.

Questions and Calculations:

1) On your graph, record 2 coordinates for 10.0 mL and 20.0 mL.

2) Calculate the slope and record your work on the graph sheet.

3) In the table below, rewrite the slope value using the correct units.

|Liquid |Slope Value + Unit |

|Water | |

|Methanol | |

|Salt solution | |

4) Using your graph, identify the mass of 6.5 mL of methanol

5) Using your slope, calculate the mass of 6.5 mL of methanol.

6) Compare your answers to Questions 4 and 5, and explain why they might not be identical.

7) What is the accepted value for the mass of 1 mL of water?

8) Use your graph to find the mass of 1 mL of water.

9) Identify 3 possible causes of error other than mathematical errors.

(Be more specific than mentioning human error)

Conclusion: (answer the purpose)

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download