Question

1) - A solution was prepared by dissolving 43.0 g of KCl in 225 g of water.

Part A

Calculate the mass percent of KCl in the solution.

Express your answer with the appropriate units.

Part B

Calculate the mole fraction of the ionic species KCl in the solution.

Express the concentration numerically as a mole fraction in decimal form.

X =

?

Part C

Calculate the molarity of KCl in the solution if the total volume of the solution is 239 mL.

Express your answer with the appropriate units.

Part D

Calculate the molality of KCl in the solution.

Express your answer with the appropriate units.

2)- How much energy is required to heat 90.7 g acetone (molar mass=58.08 g/mol) from a solid at -154.0°C to a liquid at -42.0°C? The following physical data may be useful.

ΔH_fus = 7.27 kJ/mol
C_liq = 2.16 J/g°C
C_gas = 1.29 J/g°C
C_sol = 1.65 J/g°C
T_melting = -95.0°C

3)- The decomposition of XY is second order in XY and has a rate constant of 7.12×10^−3 M−1⋠s−1 at a certain temperature.

Part A

How long will it take for the concentration of XY to decrease to 12.5% of its initial concentration when the initial concentration is 0.200 M?

Part B

If the initial concentration of XY is 0.050 M, what is the concentration of XY after 600 s ?

4) - This table displays the vapor pressure of a substance at several different temperatures.

Part A

Use the data to determine the heat of vaporization of the substance in units of kJ/mol. Hint: use Excel

vap 200 210 220 230 235 65.3 134.3 255.7 456.0 597.0