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63 Cards in this Set
- Front
- Back
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What is a solute? |
A substance dissolved in a solution |
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What is a solvent? |
The solution a substance is dissolved into |
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What dissolves in polar solvents? |
Polar substances |
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What dissolves in non-polar solvents? |
Non-polar substances |
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What are molecular compounds? |
Polar Soluble in water Non-electrolytes e.g. small alcohols (CH3OH), sugars (glucose) |
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Why do molecular compounds dissolve in water? |
H-bonds formed in the solid (or liquid) are replaced by H-bonds from water |
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What happens when molecular compounds dissolve in water? |
The solution contains intact molecules |
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What are electrolytes? |
Contain ions Electrical conductors in aqueous solutions |
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What are ionic compounds? |
Polar Soluble in water e.g. NaCl, MgCl2, K2SO4 |
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What happens to ionic compounds in water? |
Dissolve into their component ions Water stabilises the ionisation of ionic compounds by electrostatic interactions - slight negative charge on the O interacts with the cation -slight positive charge on the H interacts with the anion |
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Why are water molecules attracted to ions? |
Because of ion-dipole interactions |
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Why is electrical conductivity high in solutions containing ions? |
The compound is completely dissociated |
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What is meant by fully dissociated? |
Only ions are present in a solution |
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What are the types of electrolytes? |
Strong electrolytes Weak electrolytes |
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What are weak electrolytes? |
Solutions that contain ions + undissociated compounds e.g. small carboxylic acids (HCOOH, CH3COOH), amines (NH3, CH3NH2) |
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What is partial dissociation? |
Ions + molecules present in a solution |
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Why is electrical conductivity low in weak electrolytes? |
The compound is not completely dissociated |
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What do electrolytes do in the body? |
Found in body fluids Help transmit electrical impulses for functioning of the heart, muscle + nerves Regulate; body's hydration, blood pH |
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What are some of the main electrolytes found in the body? |
Sodium Potassium Magnesium Chlorid Calcium |
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What do low levels of Na+ do to the body? |
Hyponatremia - causing fatigue + confusion |
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What do high levels of Na+ do to the body?
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Dehydration of cells; hypernatremia, can lead to seizures, coma or death |
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What do low levels of K+ do to the body?
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Muscle weakness, leg cramps, drowsiness, confusion, loss of appetite + abnormal heartbeat |
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What do high levels of K+ do to the body?
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Hyperkalemia: low cardiac conduction + can result in cardiac arrest if not treated |
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What do low levels of Mg2+ do to the body?
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Cardiac muscle irritability, leading to abnormal heartbeat |
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What do high levels of Mg2+do to the body?
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Hypermagesium; respiratory depression, low blood pressure, slow heart rate, kidney failure |
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What do low levels of Ca+ do to the body?
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Bone pain, sudden seizures + muscle tremors |
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What do high levels of Ca+ do to the body?
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Bone pain, sudden seizures + muscle tremors |
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What are molecular compound/non-electrolyte solutes? |
Compounds of this type are non-electrolytes as they do not contain ions + electrical conductivity in aqueous solutions is very low |
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What is meant by undissociated? |
Only molecules present in solution |
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What is the Arrhenius concept of an acid? |
A substance that, when dissolved in water, increases the concentration of hydronium ion (H3O+) |
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What is the Arrhenius Concept of a base? |
A substance that, when dissolved in water, increases the concentration of hydroxide ion, OH-(aq) |
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What limits the Arrhenius concept of acids + bases? |
Only looks at acids + bases in aqueous solutions Also, it singles out the HO- ion as the source of base character, when other species can play a similar role |
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What is the Bronsted-Lowry concept of an acid? |
The species donating a proton in a proton-transfer reaction |
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What is the Bronsted-Lowry definition of a base? |
The species accepting a proton in a proton-transfer reaction |
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What is a conjugate acid-base pair? |
Two species whose composition differ by a H+ ion e.g. HCO-(aq)(Acid) + CO3^2-(aq)(Base) |
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What is the lewis concept of an acid? |
A species that can form a covalent bond by accepting an electron pair from another species |
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What is the lewis concept of a base? |
A species that can form a covalent bond by donating an electron pair to another species |
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What is a strong acid? |
A substance that ionises/dissociates completely in aqueous solution to give H3O+ and an ion |
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What is a strong base? |
A substance that ionises completely in aqueous solution to give OH-(aq) and a cation |
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What is a weak acid? |
A substance that is partially dissociated/ionised in aqueous solution to give H3O+ and an anion |
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What is a weak base? |
A substance that is partially dissociated/ionised in aqueous solution to five OH-(aq) and a cation |
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What is meant by concentrated? |
Contains a high concentration of acid/base (>1 mol l-1) |
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What is meant by dilute? |
Contains a low concentration of acid/base (<1 mol l-1) |
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What is the pH scale? |
Measures the acidity/alkalinity of a substance |
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What is an acid dissociation constant? |
Ka Where the equilibrium lies |
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What is a degree of dissociation? |
a I.e. fraction of molecules that react with water to produce ions |
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What else can represent Ka? |
pKa |
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What does small Ka reflect? |
How little of the acid is dissociated The smaller Ka, the less dissociation |
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What is Kb? |
Base-ionisation constant Very small small Kb reflects how little of the base is ionised The smaller Kb, the less ionised - the weaker the base |
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What is another way of representing Kb? |
pKb |
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What is a salt? |
anion + cation |
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What is Le Chatelier's Principle? |
The concentrations of reactants + products in an equilibrium mixture will alter so as to counteract any changes in temperature, pressure or concentration |
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What can a deviation from the slight alkalinity of blood lead to? |
Instability of cell membranes Changes in protein structure Deactivation of enzymes acidosis pH<7.35 alkalosis pH>7.45 |
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How is the pH of blood regulated? |
Regulated by a carbonic acid/bicarbonate equilibrium system Based on Le Chatelier's Principle |
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What causes acidosis of blood? |
Build up of CO2 - e.g. due to emphysema Le Chatelier's principle shifts right [H+] increases pH falls |
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What causes alkalosis? |
Drop in level of CO2 - e.g. due to hyperventilation Le Chatelier's principle shifts left [H+] decreases pH rises |
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What is a buffer? |
A solution that maintains a relatively constant pH when a small amount of acid or base is added |
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What composes an acidic buffer? |
weak acid + salt of this acid |
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What is a conjugate base? |
The salt of an acid |
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What is a conjugate acid? |
The salt of a base |
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What composes a basic buffer? |
weak base + salt of the weak base |
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What are methods of monitoring titrations? |
pH meter Conductivity pH paper Indicators |
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What are polyprotic acids/bases? |
Molecules containing multiple ionisable groups |
