Question

please answer all these questions because most of the answer you give back are always incomplete to the questions. please do well to answer all. thank you

What type(s) of intermolecular forces are expected between CS2 molecules? ball & stick - + labels Indicate with a Y (yes) or an N (no) which apply. dipole forces induced dipole forces hydrogen bonding

Answer 1

1. Induced dipole forces or London dispersion forces exist in CS₂. There are no dipole-dipole or hydrogen bond forces.

2. Ammonia is a polar molecule (1.42 D), and so it exhibits all three of the van der Waals forces: Keesom forces (dipole-dipole attraction), Debye forces (induced attraction) and London dispersion forces (which all molecules exhibit). Because hydrogen is bonded to nitrogen, it exhibits hydrogen bonding.

3. Dipole-dipole forces and hydrogen bond can exist in CH3CONH2 molecules.

4. All three types of forces exist in 1-Hexanol molecule.

5. Dipole and induced dipole forces are present in CH3CH2CHO. No hydrogen bonding since H is attached to C-atom not O.

6. (A) is the correct answer.

Alkanes are nonpolar and are thus associated only through relatively weak dispersion forces. Alkanes with one to four carbon atoms are gases at room temperature. In contrast, even methanol (with one carbon atom) is a liquid at room temperature. Hydrogen bonding greatly increases the boiling points of alcohols compared to hydrocarbons of comparable molar mass. The boiling point is a rough measure of the amount of energy necessary to separate a liquid molecule from its nearest neighbors. If the molecules interact through hydrogen bonding, a relatively large quantity of energy must be supplied to break those intermolecular attractions. Only then can the molecule escape from the liquid into the gaseous state. Also longer the chain, higher the molecular weight and more will be the boiling point.

7. SiH₄ is the correct answer with lower boiling point than H₂S.

Model 1: Boiling Points Change Down a Group of the Periodic Table Molecules are held in the liquid phase due to intermolecular forces so that boiling points are a good guide to their strength. The figure opposite shows the boiling points of the Group 14 hydrides. All have the same shape but differ in the total number of electrons. For example: boiling point /K Gel SiH, Chas 6 electrons and each H has 1 electron so CH, has 6+4 x 1 = 10. Sn has 50 electrons so SnHe has 54 electrons. 0 10 50 60 20 30 40 number of electrons •

Intermolecular Forces Model 2: Boiling Points Change Across a Row of the Periodic Table On the graph opposite, the boiling points for the other hydrides have been added: • Group 14 SiH4, GeH4 and SnH4 • Group 15 PH3, AsHz and SbH; Group 16 A Group 16 H2S, HSe and H, Te Group 17 • Group 17 HCI, HBr and HI Group 15 Group 14 1 boiling point / K 1 20 60 number of electrons

8.

400 Model 3: Anomalous Boiling Points of NH3, H20 and HF The graph opposite adds the boiling points of CH4, NH3, H20 and HF to Model 3. N, O and F are very Group 16 A electronegative and N-H, O-H and H-F bonds are very polar. 30Group 17 Critical thinking questions Group 15 O 200 1. How do the boiling points of the Group 14 hydrides change down the group? boiling point / K 10Group 14 20 40 60 Re-read your answers to Model 1. number of electrons