Question

unit 3 practice #2
21.
an ionic crystal is added to water and starts to dissolve as shown in the particulate representation above. based on
the orientation of the water molecules, what can be assumed about the charge of the hydrated particle indicated by
the arrow?
(a) the particle is positively charged, because the oxygen atoms in water are attracted to it.
(b) the particle is negatively charged, because hydrogen atoms in water are attracted to it.
(c) the particle is both positively and negatively charged, because the water molecules are attracted to it.
(d) the particle is neutral, because the dipoles of the water molecules neutralize the charge of the particle.

Explanation:

Water is a polar molecule. The oxygen atom in water has a partial negative charge (\(\delta -\)), and the hydrogen atoms have partial positive charges (\(\delta +\)). Opposite charges attract. If the hydrogen atoms (with \(\delta +\)) in water are oriented towards a hydrated particle, it means the particle has a negative charge. This is because the positive - partial charge of hydrogen is attracted to the negative charge of the particle.

Answer:

B. The particle is negatively charged, because hydrogen atoms in water are attracted to it.