Biology basics Flashcards
How many lone electron pairs does a water molecule have?
Two
What kind of shape does a water molecule have?
Tetrahedron - because of the two lone electron pairs and the two covalent bonds with the hydrogen atoms. Both the electron pairs and the bonds repel each other, however the bonded electrons are less repellent and stay at the same “end” of the molecule together.
True or false: Water is not a particularly good solvent
False - water acts as a solvent in many biological processes
Which feature of water molecules makes it a good solvent?
Their polarity
What does the suffix -ide usually indicate?
The monoatomic anion of an element
An the molecular formula of an ionic bond, what is the order of the ions?
The cation is first, then the anion.
Are hydrocarbons hydrophobic or hydrophilic?
Hydrophobic - they are non-polar
What does -ane indicate in chemisty?
A saturated hydrocarbon
What is hexane?
A six-carbon saturated hydrocarbon
What is this molecule called?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/291/608/983/q_image_thumb.png?1572245375)
Hexane - hex means 6, -ane means a saturated hydrocarbon. So this is a saturated hydrocarbon with six carbons.
Define aqueous solution?
A solution in which water is the solvent.
Define a solution
A mixture of solute and solvent
What is a solvent?
A substance that can dissolve other compounds and molecules.
The process in which molecules or ionic compounds separate or split into smaller particles such as atoms, ions, or radicals, usually in a reversible manner.
Dissociation
Define dissociation
The process in which molecules or ionic compounds separate into smaller components like ions or atoms, usually in a reversible way
True or false - when sodium chloride is placed in water, it dissociates into sodium and chlorine atoms.
False - it dissociates into sodium and chloride ions. The charges of each ion attract different ends of the water molecules which create hydration shells around each ion.
What is the relationship between temperature and solubility for water, and what is the exception?
Usually, the higher the temperature, the higher the solubility. The higher temperature increases kinetic energy so the solvent molecules can more effectively break apart the solute molecules that are held together by intermolecular attractions. Unless the solute is a gas.
What is this called and why is it happening?
![](https://s3.amazonaws.com/brainscape-prod/system/cm/291/609/480/q_image_thumb.jpg?1572246866)
Concave meniscus - occurs when the water molecules in a container are more attracted to the molecules of the container than to each other.
Define capillary action
The ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity. It occurs because of intermolecular forces between the liquid and surrounding solid surfaces.
What is the name of the process by which water is absorbed into a paper towel?
Capillary action
What is cohesion?
Cohesion refers to the attraction of molecules for other molecules of the same kind
What do we call the attraction of molecules to other molecules of their same kind?
Cohesion
Define adhesion
The attraction of molecules of one kind to molecules of a different kind
What do we call the attraction of molecules of one kind to molecules of a different kind?
Adhesion
Which intermolecular force is responsible for surface tension?
Cohesion
Capillary action occurs when _____ forces are stronger than _____ forces
adhesive, cohesive
Explain why sweating cools us down
Heat is kinetic energy. The kinetic energy from our body heat is transfered to the water molecules in sweat. When that energy becomes enough to break the hydrogen bonds (and overcome pressure), a water molecule will enter its gaseous state - it evaporates. When the high kinetic energy molecules evaporate, the average kinetic energy remaining goes down and temperature reduces.
Define specific heat
The amount of heat required to raise 1 gram of a substance by 1 degree celsius
What do we call the amount of heat energy required to raise one gram of a substance by 1 degree celsius?
The specific heat
What is the name of the specific heat for water?
The calorie
True or false: The number of calories on food labels correspond to how many grams of water could be heated by 1 degree celsius by the energy in the food.
False - food labels use kilocalories, so the number given refers to how many kilograms of water could be raised by 1 degree celsius
Land has a _____ specific heat than water.
Lower
At a molecular level, what is temperature?
Average kinetic energy
Compared to other liquids, water has a _____ specific heat
High
What is the process by which hydronium and hydroxide are produced called?
Autoionisation of water
What is H30+ called?
Hydronium
What is HO- called?
Hydroxide
What is the molecular formula of hydronium?
H3O+
What is the molecular formula of hydroxide?
HO-
Describe autoionization of water
This occurs when the hydrogen proton from one water molecule forms a coordinate bond with the oxygen of another molecule, leaving behind its electron. The resulting cation has three hydrogens (one with a net positive charge as it did not bring an election with it) and is called hydronium. The molecule that loses the hydrogen proton but retains the electron now has a net negative charge and is called hydroxide.
What is a Bronsted Lowry acid?
A molecule that dissociates in a solvent to donate hydrogen ions (H+)
What is an Arrhenius acid?
A molecule that dissociates in water to form hydrogen ions (H+)
In most cases this corresponds to a substance that increases the concentration of hydronium molecules in water, as the hydrogen ions will often bond with a water molecule.
What do we call a molecule that dissociates in water to form hydrogen ions (H+)
An Arrhenius acid (and also by extension a Bronsted-Lowry acid)
What is a Bronsted-Lowry base?
An atom/molecule that can accept a hydrogen proton