Background: Changes of state from solid to liquid and from liquid to gas occur when matter gains energy. The energy allows individual molecules to separate and move apart from one another. It takes more energy to bring about these changes of state for polar molecules. Although hydrogen bonds are weak, they add to the energy needed for molecules to move apart from one another, so it takes higher temperatures for these changes of state to occur in polar compounds. This explains why polar compounds have relatively high melting and boiling points. The Table below compares melting and boiling points for some polar and nonpolar covalent compounds.

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which compound would have higher boiling point, compound A or compound B?
Answer: compound A

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which compound would have lower boiling point, compound A or compound B?
Answer: compound B

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which compound would have higher melting point, compound A or compound B?
Answer: compound A

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which compound would have lower melting point, compound A or compound B?
Answer: compound B

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which test would need more energy, case A or case B?
Answer: case A

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which test would need less energy, case A or case B?
Answer: case B

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Would case A need less or more energy than case B?
Answer: more

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Would case B need less or more energy than case A?
Answer: less

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which test would need higher temperature, case A or case B?
Answer: case A

Situation: Mike was interested in the science behind polar compounds. To that end, he collected two compounds, compound A and compound B. Compound A was a polar compound, but compound B was a nonpolar compound. He then conducted two tests, case A and case B. In case A, he changed the state of a polar compound from solid to liquid. And, in case B, he changed the state of a nonpolar compound from solid to liquid.

Question: Which test would need lower temperature, case A or case B ?
Answer: case B