Gabriella. Gellings ecooa dias Pre-Laboratory Assignment you take with There ere

Question

Gabriella. Gellings ecooa dias Pre-Laboratory Assignment you take with There ere Pew recau rors you sneuvo "are on or thorn not sn PF. Pro her Precaution ovie be when ab using his use 9 asses or 2. lab coot and use ve de cume Briefly explain why there is a eon tant temperature Plateau in the coiling curve in but 3. Briefly explain why, in Figures 1 and 2, the temperature rises immediately after me crystals 4. If you could only record a single temperature reading in a freezing point determination experiment. which temperature should you record? This is the point that you should observe most carefully when carrying out the experiment) 5 Briefly explain why it is important for the beaker of water to cool slowly and for you to stir the naphthalene liquid as it cools.

Explanation / Answer

Post lab

1. To cool the liquid slowly, the apparatus need to be cooled much more slowly so it should be more evenly cooled from all sides. Increasing the size of container would help in this.

2. Using equations

dTf = iKfm

8.4 = 1 x 37.7 x mass of naphthalene/128.17 x 0.012

mass of naphthalene to be added = 0.342 g

3. dTf = iKfm

71 - 21.1 = 1 x 1.44 x Kf/176.2 x 0.01287

Kf = 78.58 oC/m

4. dTf = iKfm

71 - 39.9 = 1 x 8.12 x 1.64/molar mass of unknown x 0.01822

So,

molae mass of unknown = 23.50 g/mol

Related Questions

Navigate

• Browse (All)
• Browse G
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.