Question

A 1.5-Liter solution contains 45.0 mL of ethylene glycol. What is the volume percent of ethylene glycol in the solution?

In which group are ALL the molecules capable of hydrogen bonding?

		C6H14, I2, CO2
		HF, NH3, H2O
		CO, Ne, NaCl
		CH3F, HCN, H2

For which group of substances are dispersion forces the ONLY forces acting between molecules?

		C6H14, I2, CO2
		HF, NH3, H2O
		CO, Ne, NaCl
		CH3F, HCN, H2

Which pair of compounds will NOT mix to form a solution?

		H2O and sugar (C12H22O11)
		butane (C4H10) and benzene (C6H6)
		H2O and benzene (C6H6)
		butane (C4H10) and hexane (C6H14)

Ne

CO₂

CH₃OH

LiF

The substances shown above are ordered correctly from (Ne) lowest to (LiF) highest with respect to ________________

		molar mass
		total number of valence electrons
		number of double bonds
		boiling point

Answer 1

• Given that 1.5L of solution contain 45 ml of ethylene glycol.

To find: volume percent of ethylene glycol.

1.5L = 1500ml

So, volume percent = (45/1050) × 100 = 4.29%

• second group i.e., HF, NH3, H2O all are capable of hydrogen bonding.

In HF, F is more electronegative atom which will do hydrogen bonding, in NH3, Nitrogen has lone pair of electron which will do hydrogen bonding similarly in H2O, oxygen has lone pair of electron which has the capacity to do hydrogen bonding.

• H2O and benzene will not mix to form a solution.

Benzene is nonpolar and water is highly polar. If we add benzene to water, benzene will float on the top of the water with no apparent mixing.

The attractive forces among the benzene molecules are relatively weak London dispersion forces.

The attractive forces among the water molecules are relatively strong hydrogen bonds.

The only attractive forces among the benzene and water molecules are London forces.Thus, a few benzene molecules will enter the water layer, but the strong hydrogen bonds among the water molecules keeps most of the benzene molecules out.

• Boiling point.

As among these substances Ne has lowest boiling point -246°C, and that of LiF has highest boiling point 1676°C.