Water, pH and Macromolecules
Buffer solutions

will always have a pH of 7
are rarely found in living systems
cause a decrease in pH when acids are added to them.
tend to maintain a relatively constant pH.

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Water, pH and Macromolecules
Salt dissolves well in water as water molecules

form hydrogen bonds with the positively and negatively charged ions
share electrons with the ions to make polar covalent bonds
surround the ions because of their charge but do not form hydrogen bonds
make nonpolar covalent bonds with the positively charged ions only

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Water, pH and Macromolecules
Which of the following statements about covalently bonded molecules is false?

The chemical bonds that hold the molecule together are relatively strong
Electrons are shared between the atoms that make up the molecule
Noncovalent bonds may also be present, especially if the molecule is large
Such molecules often result from the interaction of ionized atoms

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