The hydrogen bonding that occurs in water is responsible for a...

Question

The hydrogen bonding that occurs in water is responsible for all of the following except

(a) The high boiling point of water

(b) The low freezing point of water

(c) The ability of water to dissolve nonpolar substances

(d) The ability of water to dissolve inorganic salts

(e) The surface tension of water

Accepted Answer

Welcome back everyone. Which of the following is the reason why water molecules move through the xylem vessel during transpiration. We have a the adhesive property of water molecules due to the presence of hydrogen bonds, B, the cohesive property of water due to the presence of hydrogen bonds, C the polarity of water molecules due to the unequal sharing of electrons. D the hexagonal lattice structure of water molecules or E both choices A and B. Let's start by recognizing that the term transpiration is defined as the process where plants absorb water through their roots and then release water as vapor from their leaves into the atmosphere. And so we should recognize that a xylem vessel are going to be vessels that are located in the vascular tissue of plants and vascular tissue recall is going to be tissue responsible for the transport of water, nutrients and minerals throughout a plant and recall that it consists of xylem and flow. Now, we're going to focus on xylem for this example and we're going to draw a general sketch of a plant xylem vessel. We'll start at the top of the xylem vessel which consists of perforation plates. So let's label that as perforation plates and from the perforation plates, we will draw the walls of the xylem vessel. And let's consider this to actually be a cross section of the xylem. And so we would be looking at the inside of the xylem where we can observe water molecules are going to be present. And I will represent those water molecules as circles within the xylem. Now recall that water is a polar molecule. So it has a partially positive end and a partially negative end. So drawing those in as plus and minus signs on each circle representing the water molecules, we're going to recall that there's going to be an attraction from the partial positive to the partial negative ends between each of these water molecules. And we will recognize those attractions by the dotted lines that I am representing and those who will represent cohesive forces between each of the water molecules. We will also take note of the fact that the xylem wall composition is made up of substances known as lignin and cellulose. Let's recall that Lina and cellulose contain the functional group known as hydroxyl groups or oh groups. And so they are capable of hydrogen bonding. So, livid and cellulose are going to be otherwise known as hydrophilic and recall that hydrophilic characterizes something as being water loving. And this therefore correlates to the adhesion of water molecules to the xylem walls which occurs via hydrogen bonding. So we will depict that adhesion by purple dotted lines from the water molecules to the xylem walls. These are again representative of adhesive forces. Now, together recall that the cohesive and adhesive forces of the xylem vessel are representative of the TC A mechanism or transpiration cohesion adhesion mechanism. And it is this mechanism that allows for the continuous water column of the xylem which ensures uninterrupted water transport in order to maintain water balance within plants. So based on everything we've outlined, looking at our answer choices and focusing on the reason for the movement of water molecules during transpiration, we have choice, a the adhesive property of water molecules due to the presence of hydrogen bonds, we will place a checkmark by choice. A because that aligns with what we covered. And then we have choice b the cohesive property of water molecules due to the presence of hydrogen bonds is also going to be another correct choice. Then we have c the polarity of water molecules due to the unequal sharing of electrons, as we stated, water is a polar molecule. However, its polarity does not explain the movement of the water molecules within the xylem. So for that reason, we will rule out choice e because again, polarity does not explain the movement. And then we have d the hexagonal lattice structure of water molecules recall that the hexagonal lattice structure of water pertains to water in its solid form as ice. And in the xylem, we will not be considering water as ice. So for that reason, D is also an incorrect answer. And then we have E which groups together choices A and B which cover the adhesive and cohesive properties of water molecules due to their presence of hydrogen bonds. And as we stated, those properties are part of the transpiration cohesion adhesion mechanism which ensures that continuous water column and movement of water to hydrate plants. And so for that reason, choice, E is going to be the best answer and final answer to complete this example. So the reason that water molecules move through this island vessel during transpiration is e both due to the adhesive and cohesive property of water molecules due to the presence of hydrogen bonds. This is our final answer. I hope this makes sense and let us know if you have any questions.

Key Concepts

Hydrogen Bonding

Polarity of Water

Dissolution of Substances

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