Boiling Point Lab

Boiling Point Lab • Use the cheat sheet to help you complete your lab report!!

Boiling Point Lab Report • PURPOSE: • The purpose of this experiment is to determine the amount of salt in an unknown water sample by determining its boiling point

Boiling Point Lab Report • BACKGROUND INFO: • List and describe details you know about boiling, boiling water, adding salt to water, etc.

Boiling Point Lab Report • HYPOTHESIS: • By examining the unknown, take a guess as to the amount of salt per 200 mL. • (You can do this after you get in lab)

Boiling Point Lab Report • MATERIALS & EQUIPMENT: • You can list these materials after using them in lab • There are a few safety concerns which will be covered later

What is the purpose of the Boiling Point Lab? • To heat water to the highest temperature possible • To evaporate all the water from a salt water mixture • To identify the amount of salt in an unknown mixture

Boiling Point Lab Procedures • Measure 200 mL of water & put it in flask • Add salt (this will vary) – 0 g FIRST TRIAL • Dissolve salt by swishing flask around • Insert thermometer & heat on hot plate • Measure temp every minute (Table 1) • Temp will stop rising at boiling point (Table 2) • Take off hot plate using flask tongs • Do not dump hot water. Let it cool. • Repeat procedure using different flask

Boiling Point Lab Safety Concerns • Hot plates, heated glass & water may cause severe burns – Be cautious • Hot glass & cold glass look exactly the same – Assume it is hot!! • Keep cords from hanging over table to prevent snagging and hot liquid spills • Do not put face or any body parts directly over flask opening

Boiling Point Lab Safety & Equipment Concerns • When in the same area as anyone heating liquid, you must wear goggles (THIS IS STATE LAW) • Never put anything into water when it is boiling • Hot plates are for heating liquids only (Any student using them improperly will be dismissed WITHOUT warning)

Boiling Point Lab Equipment Safety • Never expose thermometers or other equipment to LARGE TEMPERATURE CHANGES – especially not glass!!! • Keep cords away from hot plate • Use the flask tongs to remove the flask from the hot plate (DO NOT ATTEMPT TO USE TONGS TO DUMP OUT HOT LIQUID!!) • Wait until the liquid cools enough to dump out by hand

How much water should go in the flask for each trial? • Fill it up • 100 mL • 200 mL • Doesn’t matter

How should the hot water be dumped out? • Using the lab tongs, dump it while still hot so that it can be used immediately • Grab the flask by hand from the hot plate and dump it • Remove the flask with tongs, set it down until cool enough to dump by hand

Standard Lab Rules • 1.) Stay on task • 2.) Use equipment properly • 3.) Clean up after yourself

Do you understand and agree to abide by the lab rules & procedures for personal & equipment safety in this experiment? • Yes • No

Boiling Point Lab • Are you ready? • OR • Re-test?

How much water should go in the flask for each trial? • Fill it up • 100 mL • 200 mL • Doesn’t matter

How should the hot water be dumped out? • Using the lab tongs, dump it while still hot so that it can be used immediately • Grab the flask by hand from the hot plate and dump it • Remove the flask with tongs, set it down until cool enough to dump by hand

Do understand and agree to abide by the lab rules & procedures for personal & equipment safety in this experiment? • Yes • No

Boiling Point Lab • Finishing up the lab report

Boiling Point Lab Procedures • Measure 200 mL of water & put it in flask • Add salt (this will vary) – 0 g FIRST TRIAL • Dissolve salt by swishing flask around • Insert thermometer & heat on hot plate • Measure temp every minute (Table 1) • Temp will stop rising at boiling point (Table 2) • Take off hot plate using flask tongs • Do not dump hot water. Let it cool. • Repeat procedure using different flask

Results • Explain what the data tables and graph show plus any other significant observations • Be specific as to why the data tables & graphs were included as well as what you learned from the data

Table 2Boiling Points • Determine the temperature at which the salt-water mixture stopped rising. • Record this as the boiling point for each mixture tested.

What is the independent variable in this experiment? • Boiling Point • Amount of Salt • Temperature • Time

What is the dependent variable in this experiment? • Boiling Point • Amount of Salt • Temperature • Time

Variables • What are some controlled variables in this experiment? • What are some variables that could have been controlled better?

Graph 1Boiling Point vs. Amount of Salt • Amount of salt on x-axis • (measured in grams) • Temperature on y-axis • (measure in degrees Celsius) • Plot points • Draw line of best fit • Determine where boiling point of unknown intersects the line

Results • Explain what the data tables and graph show plus any other significant observations • Be specific as to why the data tables & graphs were included as well as what you learned from the data

Analysis • Be sure to share how much salt you believe there is in the unknown mixture. • Be sure to mention possible sources of error in the experiment (variables not controlled really well would be great to mention here)

Approximately how much salt did you estimate is in the unknown? • 0 g • 5 g • 10 g • 15 g • 20 g • 25 g • 30 g • 35 g

Boiling Point Lab Report • Finish up Lab Report • When finished turn in or if not, then finish ON YOUR OWN & turn in Monday!! Turn in your remotes

Boiling Point Lab