Measurement of Mass and Volume - Using a Bunsen Burner

HONORS CHEMISTRYNAME______PER______

MEASUREMENT OF MASS AND VOLUME - USING A BUNSEN BURNER

PART 1: DISCOVERING THE ACCURACY OF SEVERAL DIFFERENT MEASURING DEVICES

1. Weigh an empty 125 mL flask. Record its mass in the space provided on data table 1.

Fill a buret with water adding the water over the zero line. Open the stopcock and collect the water in an empty beaker until the meniscus rests at the exact 0 point.

Now dispense 25.00 mL of water from the buret into the 125 mL flask. Record this value as the experimental volume. Remass the flask and water and record the mass of the flask + water in the table in the space provided. DO NOT EMPTY THE FLASK AT THIS TIME.

2. Calculate the mass of water by subtracting your two previous masses. Using the density of water, calculate the volume of water actually used (This is called the actual volume). You must take the temperature of the water and ask your teacher for the density value of water for that temperature.

When taking the temperature, make sure that the tip of the thermometer rests in the center of the water in the beaker and does not touch the sides of the glass.

Record that temperature value here ______. Record that density value here ______.

3. Calculate the % of error as follows: (note: in this example experimental value = experimental volume, etc. - in other cases in this lab, experimental value may equal experimental density, etc.)

% error = |Experimental value - accepted value| X 100

accepted value

4. Getting water from the sink, measure 25.0 mL of water with a 25 mL graduated cylinder. Record the experimental volume in the space provided. Add that water to the original 125 mL flask that already has some water in it. Mass the flask and record the mass in the space provided. Repeat steps 2 and 3 in order to finish your calculations ( you don’t need to take the temperature and find the density again - those values can be reused ).

5. Repeat step 4 measuring out 25 mL of water from the sink this time into a 250 mL beaker. Follow all directions from step 4 starting with the second sentence.

PART 2: DISCOVERING THE ACCURACY OF SIMILAR CONTAINERS OF DIFFERENT SIZES

1. This experiment is an exact repeat of the experiment above only you will measure out 10.0 mL of water from the sink each time into different size graduated cylinders.

2. Empty your flask from part one and remass it recording the mass in the space provided in data table 2.

Getting water from the sink, measure 10.0 mL into the 10 mL graduated cylinder. Record the experimental volume. Add the water to your already massed flask and remass it again. Record the mass in the space provided marked mass of flask + water. Using instructions from part 1, calculate the mass of water, accepted volume and % of error ( you can reuse the temperature and density values from part 1 again). DO NOT EMPTY THE FLASK BETWEEN TRIALS.

3. Repeat the experiment using (a) a 25 mL cylinder, (b) a 50 mL cylinder, and (c) a 100 mL cylinder. Please note that you will be using 10.0 mL of water in each trial.

PART 3: CALCULATING DENSITY USING TWO DIFFERENT METHODS FOR FINDING VOLUME

A. Trial 1 - Direct Method

1. Obtain a metal slab. Record its mass in the space provided marked mass. Please note that this will serve as the mass for trial 1 and 2.

2. Using a metric ruler, record the length, width, and height of the block in the table below.

3. Calculate the volume. Calculate the density. Using 2.70 g/cm3 as the accepted value, calculate % error.

B. Trial 2 - Water Displacement Method

1. Fill a 100 mL graduated cylinder ( this is a special graduated cylinder used only for part three of this lab) to the 40.0 mL mark with water from the sink.

2. Turn the graduated cylinder gently to the side so that the water in the cylinder begins to near the top. Gently slide the metal slab into the cylinder and slowly turn the graduated cylinder to its upright position. Read the new volume of water now in the cylinder. Record that new volume here______.

3. Using the increase in the water level as the volume of the metal slab, and the previous mass of the slab, calculate the density. Using 2.70 g/mL as the accepted value, calculate % error.

PART 4: DISCOVERING HOW TO USE A BUNSEN BURNER EFFECTIVELY

1. Using a 100 mL graduated cylinder, measure 100.0 ml of water and add to a 250 mL beaker. Record the temperature of the water in the beaker ( initial temperature).

2. Place the beaker on a wire gauze pad on a ring stand with the ring stationed approximately 30-40 centimeters above the table. Heat the beaker for three minutes with a cool setting (the original setting you used to light the burner). Record the highest temperature reached ( final temperature) at the end of three minutes after you have shut off the burner.

3. Empty the beaker and add another 100 mL of water to it. Repeat the experiment above with one change. This time open the burner allowing more air to enter until you see a blue flame within the flame ( a hot setting ). Make sure you record the initial and final temperatures again.

4. Empty the beaker again and add another 100 mL of water to it. Repeat the experiment above with one more change. This time adjust the ring stand so that the top of the inner blue flame just touches the bottom of the beaker. Remember, you have to open the burner again to achieve a hot flame. Make sure you record the initial and final temperatures again.

5. Calculate the number of calories given off by the burner for each trial using the following formula:

Calories = mass x specific heat x change in temperature

DATA TABLE 1

Mass of empty flask______g

DATA TABLE 2

Mass of empty flask______g

Lab Report Requirements:

1. Complete all of the tables in this lab sheet. Make sure to use proper significant figures.

2. Answer the following questions in the space provided:

a. What are the reasons (plural - there are many) for you doing this lab?

b. Why is the flask not emptied between the trials in part one of this lab?

c. Why is the temperature of the water measured in parts 1 and 2 of this lab?

d. Explain how to start a Bunsen burner and achieve a hot flame.

3. On a separate piece of loose-leaf paper, complete a Theory and Discussion Section for each of the four parts of this lab. Attach them to this handout. A good Theory and Discussion should include:

a. A summary of what you did in the lab, but not a step by step account ( think “topic sentence”).

b. What the results were ( include numbers and % error).

c. Explain why those results turned out the way they did. Include sources of error (this is often plural).

d. A proper Theory and Discussion section should include appropriate vocabulary that documents what you learned from the lab.

1. A proper Theory and Discussion section should be a paragraph. This may be a long paragraph, but it should not be a restatement of the procedure.

Measurement Lab notes:

1)Goggles - shoes

2)Be careful with equipment – especially burets and graduates with metal

3)Use the prescribed instrument to measure the water (ex. Don’t use the buret to put 25 mL of water in the beaker)

4)Burets – overfill, eye level, zero line, read upside down, stopcock

5)Balances – fun vs. func

6)DO NOT EMPTY FLASK!!!

7)Density Value

8)Data table 1 – only do first two columns

9)Part I – don’t calc mass of water in #2 yet, don’t do part 3 yet

Day 2

10)Be careful with equipment – especially graduates with metal

11)Bunsen burners – start closed (cool flame) – open to hot flame (blue flame within a flame)