Trial-1

Mass of Naphthalene = 5.2149 g

Kf of Naphthele= 6.94 celcius/molal

Time (Sec)	Temperature
0	95.0C
15	83.3C
30	80.3C
45	79.7C
60	79.6C
75	79.2C
90	79.0C
105	78.5C
120	78.0C
135	77.2C

Trial 2

Time (sec)	Temperature
0	95.7C
15	83.4C
30	79.6C
45	79.5C
60	79.2C
75	79.1C
90	78.8C
105	78.4C
120	78.1C
135	77.6C

Part 2

Unknown No = 3

Mass of unknown no = 0.5651 g

Trial 1 ( with unknown compound)

Time ( Sec)	Temperature
0	95.0C
15	85.0C
30	78.3C
45	74.9C
60	74.3C
75	73.3C
90	73.1C
105	72.6C
120	72.1C
135	71.5C
150	70.2C

Trial 2 ( with unknown compound)

Time ( Sec)	Temperature
0	95.0C
15	85.6C
30	78.8C
45	74.8C
60	74.4C
75	73.4C
90	73.2C
105	72.5C
120	72.0C
135	71.2C
150	70.0C

The aim of this experiment is to determine the molar mass and identity of an unknown compound by measuringthe depression in freezing point. In this experiment, we will first measure the freezing point of pure naphthalene, thenmeasure the freezing point again after mixing in an unknown solute.From the decrease in freezing point of the mixture versuspurenaphthalene,themolarmassoftheunknownwill be determined.( PossibleUnknowns:p-dichlorobenzene,benzophenone,benzyl). Forthereportyouwillneedto:

Look up the formulas and molar masses of all the possible unknowns (p-dichloro benzene, Benzophenone, Benzil)froma reliable source (CRC handbook or the NIST web book) and list them in your report.Based on your results, what is yourunknown?Explainclearlythereasonfor your choice.

Also,calculatepercenterror:

percent error=(

|actualvalue-experimentalvalue|

)100%

actualvalue

Inthis lab, the"actualvalue"will bethe looked-upmolarmassofyour chosen unknown, andthe"experimental value"

willbethemolarmassyoucalculatefromyourfreezingpoint data.Forthereportyouwillneedto:

Look up the formulas and molar masses of all the possible unknowns (p-dichloro benzene, Benzophenone, Benzil)froma reliable source (CRC handbook or the NIST web book) and list them in your report.Based on your results, what is yourunknown?Explainclearlythereasonfor your choice.

Also,calculatepercenterror:

percent error=(

|actualvalue-experimentalvalue|

)100%

actualvalue

Inthis lab, the"actualvalue"will bethe looked-upmolarmassofyour chosen unknown, andthe"experimental value"

willbethemolarmassyoucalculatefromyourfreezingpoint data. plase write for me. I need help