Which of the following statements is NOT true in regards to water, ethanol, and isopropanol?
A. H-O-H and C-O-H bond angles are all equal to 1095.
B. Two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules.
C. Dispersion forces affect all three molecules.
D. Water has the highest boiling point.
E. All of these are true.
A is not true. The bond angle in HOH is 104 degrees.
B is true.
C is true.
D is true.
E is not true because A is not true.
By the way, you may have made a typo in answer A. The bond angle you may have meant to type is 109.5o and you typed 1095 instead; howeer, that doesn't change the answer, the statement still isn't true because water is not 109.5 (or 1095).
To determine which statement is NOT true, let's evaluate each option:
A. The statement states that the bond angles in both water (H-O-H) and ethanol/isopropanol (C-O-H) are all equal to 109.5°. To verify this statement, we can look at the molecular geometry of each molecule. Water has a bent or V-shaped geometry with bond angles of approximately 104.5°, while ethanol and isopropanol have a tetrahedral geometry around the central carbon atom, resulting in bond angles close to 109.5°. Thus, statement A is NOT true.
B. This statement says that two lone pairs of electrons are assigned to the oxygen in each Lewis structure of all three molecules. To confirm this, we need to draw the Lewis structures of water, ethanol, and isopropanol. By doing so, we will see that water has two lone electron pairs on oxygen while ethanol and isopropanol have only one lone electron pair on oxygen. Therefore, statement B is NOT true.
C. Dispersion forces, also known as London dispersion forces, are present in all three molecules. These forces are weak intermolecular forces caused by temporary fluctuations in electron distribution. Water, ethanol, and isopropanol all have dispersion forces due to the presence of electron clouds around their atoms. Hence, statement C is true.
D. Water has the highest boiling point among water, ethanol, and isopropanol. To determine if this statement is true, we can compare the boiling points of these substances. The boiling point of water is much higher (100°C) compared to ethanol (78.37°C) and isopropanol (82.6°C). Therefore, statement D is true.
Based on our analysis, statements A and B are NOT true. Therefore, the correct answer is option E: NOT all of these statements are true.