Question

Need assistance with graph and pre-lab questjons

1. Refer to the vapor-liquid composition curve for a benzene/toluene solution below. a) Are benzene and toluene miscible or immiscible? b) What is the boiling point of a benzene-toluene mixture that is 20% benzene? c) What percent benzene is a benzene-toluene mixture that boils at 85°C? 110 100 95 0F-- 85 A" 80 75 0 10 20 30 40 50 60 7o 80 90 100 Molo porcont benzene 2. Refer to the Boiling Points and Composition table (Table 1). a) b) c) At what temperature does a mixture of 25.5 g of water and 74.5 g of octane boil? How is the boiling point affected when more water is added to the mixture? How is the boiling point affected when more octane is added to the mixture? 3. Based on the polarity and solubility, in roughly what range would you expect the boiling points of these mixtures to fall? a) Carbon tetrachloride (b.p. -77 C) and water b) Carbon tetrachloride and pentane (b.p. 36 °C) 2. Time (min) Start Temperature (C) |Hat |tH |귀5|H5 |7700|715 3. Does the boiling temperature rise, fall, or not change? NOT CHANGE Does that mean the composition of the liquid was: changing constant CIRCLE ONE) Discard the remaining ethanol in the non-halogenated waste. Part B: Boiling Point of a Liquid with Dissolved Solid In a 5-mL conical vial, prepare a mixture of 3.0 mL of ethanol and 1.5 g oxalic acid (b.p. very high). Attached the water-jacketed condenser and heat the mixture to boiling under reflux. 4. Observed boiling point of ethanol with dissolved solid (under reflux) 81.s c 5. How does this compare to the boiling point of pure ethanol? HIGHER Remove the condenser, and heat the mixture to boiling. Start recording the temperature when it reaches he boiling point found in Part A and continue recording it at one minute intervals for 7 minutes. 6. Time (min) Start |Temperature (eC) 161-875|872-9구|908|9CY |912 |92.( 7. Does the boiling temperature rise, fall, or not change? FISE Does that mean the concentration of oxalic acid was: increasing decreasing CIRCLE ONE) Which component must have been escaping as the mixture boiled? ETHANOU ispose of the vial contents in the non-halogenated organic waste container. Rinse the conical vial and ondenser with acetone, dispose of the rinse acetone in the non-halogenated organic waste container d let the vial and condenser dry a few minutes. Analysis: The vapor pressures and boiling points of a liquid X with and without a dissolved solid Y can be represented by a graph as shown in Figure 1. Make a similar graph from your results for Parts A and B. Label the curves ethanol and ethanol + oxalic acid. Include the measured boiling point. Refer to the graph above. How would the normal boiling point of the mixture change if you added more: a) Oxalic acid? b) Ethanol?

Answer 1

Question 1)

a) yes ,toluene and benzene both are organic compound and hence both are missible with each other.

b)From above graph 20% mixture of toluene and benzene shows boiling point is about 100° C

c)From above graph at 85°C benzene is present around 70% and 30% toluene.

los+ 100C led 3 40 7of benz-enc & o 207- mixture 75 Mtcle percent benzene