Help
Options
Didn't know it?
click below
click below
Knew it?
click below
click below
Don't Know
Remaining cards (0)
Know
retry
shuffle
restart
0:00
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Colligatives
Colligative Properties 1 and 2
| Question | Answer |
|---|---|
| What is a colligative property? | Physical properties of solutions that are dependent on the number of dissolved non-volatile solute species. |
| Name the four colligative properties | Vapour Pressure lowering Boiling point elevation Freezing point depression Osmotic Pressure |
| Briefly describe vapour pressure lowering | Vapour above the solution provided solely by the solvent, vapour pressure of the solution is lower than that of the solvent - more energy is needed to vapourise. Solute molecules replace solvent molecules at the surface, lowering tendency to escape. |
| Briefly describe boiling point elevation | The temperature at which the vapour pressure of the liquid becomes equal to atmospheric pressure. Lower VP of solution =boiling point is higher than pure solvent. Effect proportional to # dissolved species. VP needs to lower to boil at same temp solvent |
| Briefly describe Freezing Point Depression | Freezing point = melting point of a solvent is the temperature at which solid and liquid phases co-exist at atmospheric pressure. The liquid solution is in equilibrium with solid solvent - lower than pure solvent. |
| Briefly describe osmotic pressure | Is the pressure which must be applied to a solution to stop water from flowing in via a semi-permeable membrane. Important as biological membranes act as semi-permeable membranes. Unwanted movement of H20 can harm patients. |
| What is an Osmol? | Measurement of number of dissolved species. Weight in grams of a solute that is osmotically equivalent to a mole of non-electrolyte. |
| How is Osmol/L calculated? | Osmol/L = M x # of dissolved species. |
| What is osmolality? | The mass of solute that when dissolved in 1kg of water will exert an osmotic pressure equal to that exerted by a mole of an ideal un-ionised substance dissolved in 1kg of water. |
| What is osmolarity? | The mas of solute which when dissolved in 1L of solution will exert an osmotic pressure equal to that exerted by a mole of an ideal un-ionised substnace dissolved in 1L of solution. |
| What is the osmotic pressure of body fluids? | 280-300 m/Osmol/L |
| What does iso-osmotic mean? | A solution has the same number of units/volume of solute as body fluid. In theory there should be no net movement of water across the biological membrane. But some solutes will pass through - not perfect semi-permebale membranes. |
| What does iso-tonic mean? | A solution where there is no net movement of water across a biological membrane. |
| List some solutes that are permeable to biological membranes | Propylene glycol, urea, ammonium chloride, glycerol |
| Finish this sentence. Boric acid is permeable to | Red blood cells, but not the mucous lining of the eye. |
| What is a hypotonic solution? | A solution that contains a lower concentration of dissolved species. Water moves into the cells causing swelling and lysis. |
| What is a hypertonic solution? | A solution that contains a higher concentration of dissolved species. Water moves out of the cell, causing it to shrink and crenate. This can be reversed if the solution is made isotonic. |
| What can happen if a IV hyPOtonic infusion is administered to someone? | Haemolysis (swelling/lysis of RBCs), water intoxication causing pulmonary and cerebral oedema, convulsions (water invades into other parts of the body). Renal failure from haemoglobinanaemia. |
| What happens if a IV hyPERtonic infusion/solution is administered to someone? | RBC's crenate |
| How can a hypertonic IV solution be administered safely? | Administered via a central fast flowing vein, the solution will rapidly dilute, changing the tonicity and will cause minimal problems. |
| What can happen is large volumes of hypertonic solution are given? | If delivered too quickly can cause dehydration (osmotic diuresis). If given via a vein with slow circulation can irritate the blood vessel walls, causing occlusion. |
| Why must intrathecal injections be strictly isotonic? | Paratonic solution will disrupt osmotic pressure of body fluid. Can cause vomiting, headaches, more serious consequences like seizures. |
| Why can intramuscular injections be slightly hypertonic? | Encourages dilution by the tissue fluids, causing rapid absorption. |
| Why do nasal formulations need to be isotonic? | Can irritate nasal mucosa and interfere with cilial actions |
| Why do opthalmic preparations need to be isotonic? | Can irritate the mucous membranes and cause flushing from tear formation. The medication is flushed out and no therapeutic effect is received. |
| How is a hypo-osmotic/hypotonic solution made isotonic? | Add enough solute to equalise the osmotic pressure. |
| How is a hyper-osmotic/hypertonic solution made isotonic? | Dilute with another solution (e.g. water) |
| As all of the colligative properties relate to each other, why is freezing point depression used to measure osmotic pressure? | Because it is the most readily available property (in references like the APF) |
| What is the freezing point depression of body fluids, blood plasma and lacrimal fluid? | 0.52 degrees |
| A solution that is iso-osmotic with biological fluids will be isotonic provided....(finish the sentence) | That the biological membrane isn't permeable to any of the solutes |
| An aqueous solution with a freezing point higher than -0.52 will be | Hypotonic (add solute) |
| An aqueous solution with a freezing point higher than -0.52 will be | Hypertonic (add water/solution) |
| What is used to adjust tonicity of parenteral solutions? | Sodium chloride or dextrose |
| What is used to adjust tonicity of opthalmic solution? | Sodium chloride, boric acid and sometimes dextrose |
| When is boric acid not included for calculating tonicity? | For injections. Included for opthalmic tonicity calculations because it doesn't pass through the mucous membrane of the eye. |
Created by:
LDM
Popular Pharmacology sets