OCR Chemistry A – 'Polarity and IMFs' (2.2.2k-m)

S=C=S has the same shape as CO₂.

TICK ALL TRUE STATEMENTS:

• CS₂ is totally symmetrical i.e. the two dipoles cancel out.

• CS₂ is polar

• permanent dipole-dipole forces are the strongest intermolecular force in CS₂

• The C–S double bond is polar

TICK IF MOLECULE IS POLAR

• CCl₄

• CH₃CH₃

• PBr_³

TICK CORRECT STATEMENTS

• at room temperature and pressure, some covalent compounds are solids, some are liquids, and some are gases

• covalent bonds exist between molecules

• in covalent bonds, electrons are transferred between atoms

• SiO₂ contains covalent bonds

In CH₃CH₂OH(s), which intermolecular force is the strongest?

• ionic bonding

• London forces

• permanent dipole-dipole forces

• hydrogen bonding

For which group of chemicals are permanent dipole-dipole forces the strongest intermolecular force for ALL compounds?

• CO₂, CS₂, CSe₂

• CH₃Cl, NO, HF

• CH₂Cl₂, CO, PBr₃

• H₂O, H₂Se, H₂S

Which is the best explanation for H₂O having a higher melting point than H₂S

• "The hydrogen bonds in H₂O are stronger and take more energy to break."

• "The hydrogen bonds in H₂O are stronger than the permanent dipole-dipole forces in H₂S. Hydrogen bonding takes more energy to break."

• "Hydrogen bonding in water is stronger than the London forces in H₂S"

• "The H₂O molecules are held in an open lattice"

O=C=O has a lower boiling point than S=C=S.

Which is the best explanation?

• CS₂ has more electrons and stronger London forces

• CS₂ has more electrons and the bonds between molecules are stronger than in CO₂

• the C=O bond is more polar than the C=S bond, because O is more electronegative than S

• CO₂ only has London forces, whereas CS₂ has permanent dipole-dipole forces

Tags

NGSS.HS-PS1-3

Here are some standard explanations that you might use.

SELECT ANY THAT ARE NOT GOOD.

• hydrogen bonds are hold apart water molecules in an open lattice, so the solid substance is less dense

• the molecule is totally symmetrical, so the bond dipoles cancel.

• the bonds between molecules are broken when boiling

• ionic bonds are much stronger than intermolecular forces so need more energy to overcome

Which of the series of steps is the correct recipe to judge the strongest intermolecular force in a substance?

• 1) does the molecule contain O, F, or N atoms? 2) is the molecule polar?

• 1) does the molecule contain an O–H, N–H, F–H bond? 2) does the molecule contain lone pairs?

• 1) does the molecule contain OH, NH, FH 2) is the molecule polar?

• 1) does the molecule contain an O–H, N–H, F–H bond? 2) is the molecule polar?

TICK ALL CORRECT STATEMENTS:

If the substance has hydrogen bonding...

• the melting and boiling points will be anomalously high

• the molecule must contain an O–H bond

• it must also have London forces

• it must also have permanent dipole-dipole forces