Chem32 Chapter 5.txt
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What is a concentration?
A ratio of solutes to solution.
- amount of solute
- Concentration = —————————
- amount of solution
What is percent solution?
Percent solution is the amount of solute in 100ml of solution.
5g or 5ml of a solute in 100ml of solution would be a 5% solution.
What is weight per volume percentage or w/v solution?
The amount of -solid- solute in 100ml of solution. Every 100ml of 5% solution will have 5ml of solute in it.
What is volume percentage or v/v solution percentage?
The amount liquid solute in a 100ml solution. Every 100ml of 5% v/v solution will have 5ml of the solute.
How can you know the percentage of a solution if it is not 100ml?
Divide solute by solution and multiply by 100 :)
- amount of solute
- ------------------------ x 100 = percent solution
- volume of solution
What does "total volume" mean in regards to solutions?
Total volume would be the solution itself.
If figuring a concentration with solute/solution, total volume would be the solution on the bottom.
How to calculate the mass of a solute in a solution from the percent concentration.
You have a .9% w/v concentration. You have a total volume of 250mL. How much solute will you need?
- 10 solute
- --- = 2 concentration
- 5 solution
- x solute .9
- ----- .9% ( ----- ) = .009
- 250 mL solution 100
250 x .009 = 2.25g solute :)
What is the most common unit of concentration in clinical use?
Mass per deciliter.
How to figure parts per million or ppm.
- 1g = 1000 mg ( miligrams )
- 1mg = 1000 ug ( micrograms )
- 1L = 1000 mL ( milileters )
- 1ppm = 1ug/mL
1mg/dL = 1000mg/100mL
- 1mg/dL ------------ = 10ug/mL
What is a mole?
One mole of an element is 6.022x1023 atoms of that element.
That many atoms of an element will weigh a number of grams equal to the atomic mass ( amu ) of that element.
One mole of Magnesium (Mg) will contain 6.022x1023 atoms of magnesium and weigh 24.31 grams. The amu of Mg is 24.31
What is molecular weight?
- Molecular weight is the weight ( in amu ) of one molecule of a substance. The molecular weight of H2O is:
- H - 1.008 x 2 = 2.016 amu
- O - 16.000 amu
- 18.016 amu
One mole of H2O contains 6.022x1023
molecules of H2O and weighs 18.016 grams.
What is molarity?
The ratio of mols of solute to liters of solution.
1 mol of glucose in 1 liter of solution is 1mol/L glucose or 1M glucose.
In any solution ( not suspension, but true solution ) the solute particles ( ions, molecules ) are in constant motion. What affect does this have on the consistency of the solution
This constant motion tends to distribute the solute evently through the solution.
What is diffusion?
The tendency for particles in a mixture to become uniformly distributed.
The constant motion of the particles and the water molecules tends to keep things evenly mixed.
Solute will diffuse in a solution from higher to lower concentration.
What is a semipermiable membrane?
A barrier, often between cells in our bodies, that allow some particles, usually smaller ones, to pass through it but not others, like larger ones.
What is osmosis?
Osmosis is the movement or "net flow" of water through a semipermiable membrane.
Water can pass through both sides of the membrane. If a concentration on one side of the membrane is lower than the other side, then the flow of water will be from low concentration to high concentration.
low concentration -----> high concentration
The flow will continue until both sides have about the same concentration, if possible.
What is osmotic pressure?
The pressure built up as a result of the flow of solute from a lower concentration to a higher one.
How does molarity of a solution containing electrolyte or other ionic compound affect osmosis?
For osmosis to occur there must be a difference in molarity ( concentration ) of solution on each side of a membrane.
NaCl by itself is one NaCl molecule. When put in water NaCl dosociates into one Na ion and one Cl ion.
So one mole of NaCl in water becomes 2 moles of ions, 1 mole Na and one mole Cl.
Glucose on the other hand is a molecular compound that will not dissociate in water. The glucose molecules each stay in their molecule form. Since they don't dissociate, 1 mole of sucrose in water will remain a 1 mole solution.
How do you figure the molarity of an electrolyte in water?
Multiply the number of ions in one mole of the compound by the number of moles of the compound.
2 mole of MgCl2 becomes 1 Mg ion and 2 Cl ions in water - 3 ions x 2 moles = 6 mole solution in water.
What is the normal solute concentration in blood cells?
In concentrations higher than this the solute will not go into the cell.
In concentrations lower than this the solute will go into the cell.
What is crenation?
When molarity outside a red blood cell is higher than .28M ( more solute, less water than inside the cell ) the cell loses too much water ( lower concentration -----> higher concentration ) and the cell kind of srivels up and dies.
What is hemolysis?
When the the molarity outside a red blood cell is less than .28M ( less solute, more water than inside the cell ) and water flows into the red blood cell until it bursts.
What is tonicity?
The relationship between the molarity inside a blood cell and outside the blood cell.
If the solution is also .28M then the solution is isotonic.
What is isotonic?
Isotonic describes a solution that has a tonicity that is equal to .28M, the tonicity(?) of a blood cell.
"iso" means equal.
What is hypertonic?
Hypertonic describes a solution that has a higher concentration ( tonicity ) than the tonicity of a blood cell. A blood cell molarity / tonicity is .28M, a hypertonic solution would be higher than that, .35M for example.
"hyper" means above or more than.
What is hypotonic?
Hypotonic describes a solution that that has a lower concentration ( or tonicity ) than that of a red blood cell. Blood cell tonicity is .28M, a solution of .14M would be "hypotonic".
"hypo" means below or lower than.
What is dialysis?
Dialysis is the movement of solvent through a membrane.
**Any solute that can move through a membrane will move to the side that has the lowest concentration of that solute.
- more solute ----> less solute
If a solute can move through a membrane one direction it can go back through the other way, too. It will go in both directions but mostly from higher to lower concentration.
If a solution on one side of a membrane has .05M sucrose and .05M gluclose and the other side has .05M sucrose and .1M gluclose will dialysis occur? Will osmosis occure? Which direction?
Since side a and b both have the same amount of sucrose, dialysis will not happen for sucrose.
Since side a has less glucose than side b, dialysis will happen for glucose. The glucose will move through the membrance from side b ( higher amount ) to side a ( lower amount ).
Dialysis: higher amount -----> lower amount
Side a has less total solute and thus more water than side b. So osmosis will occur with water moving from side b to a.
Osmosis: more water -----> less water
What is an equivalent in medical chemistry?
The amount of any ion that has the same total charge as a mole of hydrogen (H+) ( +1 ) ions.
So if you need the equivalent of K, potassium you need one mole of potassium. K has a +1 charge, same as H so you need the same amount to have an equal charge or equivalent.
If you need an equivalent of Mg ( 2+ ) you would need 1/2 mole of Mg. Or, one mole of Mg equals two equivalents.
A solution contains .31 mol phosphate ions. How many equivalents of phosphate ions does it contain?
- Ok, lets start with asking what the charge of a phosphate ion is, turns out it's 3-. So one mole of phosphate ions will have 3 equivalents.
- 3 eq
- PO4 -------- 1 mol
- .31 mol x ------- ( .31 x 3 ) = .93 Eq
- 1 mol
What is dilution?
Dilution is adding solvent to a solution to reduce the concentration of the solution.
What is a formula unit?
One group of atoms that make up a compound.
H2O is a compound.
It's made up of 2H and 1O.
1 mole of H2O weighs 18.002g
.15 moles of H2O weighs 2.7003g
What is osmolarity?
osmolarity = moles of solute / 1L of solution x mole ions per mole solute
Osmolarity = M ( number of moles in one liter of solution ) x the number of ions per mole
If NaCl solution molarity was 2M ( 2 moles NaCl / 1L solution) and each mole has 2 ions ( Na and Cl ) then formula works like:
2M x 2mion / m = 4
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