WHAT’S THAT LIQUID? AN EXERCISE IN DENSITY AND DATA ANALYSIS

PURPOSE STUDENTS WILL MEASURE THE MASS OF SEVERAL VOLUMES OF A MYSTERY LIQUID AND USE THE DATA COLLECTED TO DETERMINE THE DENSITY OF THE LIQUID TO MAKE PREDICTIONS. QUESTION: HOW CAN THE IDENTITY OF A LIQUID BE DETERMINED BY MEASURING THE MASS OF VARIOUS VOLUMES OF THE LIQUID?

BACKGROUND INFORMATION MASS IS THE AMOUNT MATTER THAT MAKES UP A SUBSTANCE. VOLUME IS THE AMOUNT OF SPACE THAT A SUBSTANCE TAKES UP. DENSITY IS THE AMOUNT OF MATTER THAT EXISTS WITHIN A SPECIFIC SPACE. IT IS CALCULATED BY DIVIDING THE MASS BY THE VOLUME OF A SUBSTANCE. SUBSTANCES HAVE A CHARACTERISTIC DENSITY, AND CAN BE IDENTIFIED BASED ON THE DENSITY AND OTHER PHYSICAL CHARACTERISTICS. FOR EXAMPLE, WATER HAS A DENSITY OF 1 G/M L

HYPOTHESIS HYPOTHESIS: IF A LIQUID HAS A SPECIFIC CHARACTERISTIC DENSITY, THEN …. FINISH THE STATEMENT – YOU WILL NOT GET CREDIT IF YOU DO NOT.

PROCEDURES PROCEDURES: PLACE A CLEAN, EMPTY GRADUATED CYLINDER ON THE GRAM SCALE AND RECORD ITS MASS. USE A DISPOSABLE PIPETTE TO TRANSFER ABOUT 2 ML OF THE LIQUID INTO THE GRADUATED CYLINDER. RECORD THE MASS OF THE CYLINDER AND LIQUID ON THE DATA TABLE. ADD ANOTHER 2 ML OF THE LIQUID TO THE GRADUATED CYLINDER, AND RECORD THE NEW MASS. REPEAT THESE STEPS UNTIL YOU TRANSFERRED A TOTAL OF 10 ML INTO THE GRADUATED CYLINDER. RETURN THE SAMPLE LIQUID TO THE STORAGE CONTAINER. WASH YOUR GRADUATED CYLINDER AND REPEAT WITH THE NEXT SAMPLE LIQUID. AFTER FINISHING WITH ALL THREE MYSTERY LIQUIDS, WASH YOUR GRADUATED CYLINDER AND HANG IT TO DRY ON THE PEG RACK BEHIND THE SINK. CLEAN UP YOUR STATION AND WASH YOUR HANDS.

SAFETY PRECAUTIONS WEAR SAFETY GOGGLES TO PREVENT EYE INJURIES. WEAR APRONS TO PREVENT DAMAGE TO CLOTHING. WEAR CLOSED TOE SHOES TO PREVENT INJURY FROM BROKEN GLASSWARE. REPORT AND CLEAN UP ANY SPILLS ACCORDING TO DIRECTIONS. CLEAN UP STATION ACCORDING TO DIRECTIONS. WASH HANDS BEFORE LEAVING LAB.

RECORD & ANALYZE DATA DATA & OBSERVATIONS: MASS OF THE GRADUATED CYLINDER=_______________ VolumeLiquid ALiquid BLiquid C Total mass Liquid mass Total mass Liquid mass Total mass Liquid mass 2 mL 4 mL 6 mL 8 mL 10 mL

RECORD & ANALYZE DATA Mass of liquid (in g) Volume of liquid (in mL) Density of unknown liquids

DRAW A CONCLUSION CONCLUSION: WRITE THE EQUATION OF THE LINE DETERMINED BY THE DATA WHAT ARE THE UNITS FOR SLOPE? WHAT IS THE VALUE OF THE Y-INTERCEPT? WHAT DOES IT REPRESENT? WHAT IS THE PHYSICAL SIGNIFICANCE OF THE SLOPE? (HINT: REFER BACK TO QUESTION 2) CALCULATE THE MASS OF 7.5 ML OF EACH LIQUID. IF YOU NEED 6 G OF LIQUID B, HOW MANY ML OF THE LIQUID SHOULD YOU PUT INTO THE CYLINDER? IDENTIFY THE LIQUIDS USING THE LIST PROVIDED.

ERRORS & EXTENSIONS ERRORS & NEW QUESTIONS: POSSIBLE SYSTEMIC ERROR: POSSIBLE INDIVIDUAL ERROR: NEW QUESTION: HOW COULD YOU EXTEND THIS LAB?