Forces between molecules and boiling points

Answer Key - Grade 10 Science Worksheet - Building Confidence

Circle the best answer, or write your answer on the line.

1. 1.

   Water boils at 100 °C and hydrogen sulfide at -60.33 °C (PubChem). How many degrees higher does water boil, Ari?

   160.33 °C
2. 2.

   Ammonia boils at -33.35 °C and methane at -161.5 °C (PubChem). How many degrees higher does ammonia boil, Bo?

   128.15 °C
3. 3.

   Water boils at 100 °C and ammonia at -33.35 °C (PubChem). How many degrees higher does water boil, Esme?

   133.35 °C

4. Read this first

   Use this

   Molecule sketches side by side with dotted lines for attractions. CH₄ molecules: weak London dispersion attractions. HCl molecules: dipole-dipole attractions between the partly positive H and partly negative Cl. H₂O molecules: hydrogen bonds, O–H···O.

5. 4.

   On the card, what attraction holds CH₄ molecules together, Jun?

   • London dispersion
   • Ionic bonds
   • Hydrogen bonds
6. 5.

   On the card, what do the dotted lines between water molecules show, Kira?

   • Hydrogen bonds
   • Covalent bonds
   • Ionic bonds
7. 6.

   On the card, why do HCl molecules attract each other, Luz?

   • They are ions
   • Their partial charges attract
   • They share electrons in a bond
8. 7.

   What is overcome when water boils, Milo?

   • Bonds inside each of the molecules
   • The nuclei of the atoms
   • Attractions between molecules
9. 8.

   What is steam made of, Noah?

   • Separate H and O atoms
   • Whole H₂O molecules
   • Hydrogen gas alone
10. 9.

    For molecules of similar size, which attraction is strongest, Ren?

    • Dipole-dipole
    • London dispersion
    • Hydrogen bonding
11. 10.

    How do stronger attractions affect boiling point, Tala?

    • They lower it
    • They don't change it
    • They raise it