Buffers & Isotonic Solutions Flashcards
What is osmosis?
The passive movement of water molecules from a high water potential to a low water potential across a partially permeable membrane
What is water potential?
The pressure exerted by water molecules as they collide with a membrane or container
What are the units for water potential?
Pascals (Pa) or kilopascals (kPa)
What is hydrostatic pressure?
The pressure exerted by a fluid at equilibrium at any point of time due to the force of gravity
Describe an isotonic cell
- No net movement of water by osmosis
- No change in shape or size
Describe a hypertonic cell
- Very low water potential
- Cytoplasm has a higher water potential than it’s surroundings
- Water moves out of the cell down the water potential gradient by osmosis
Describe a hypotonic cell
- Very high water potential
- Cytoplasm has a linear water potential than it’s surroundings
- Water moves into cells down water potential gradient by osmosis
What is a buffer?
An isotonic solution that maintains a constant pH by neutralising the effects of hydrogen ions
How do you create isotonic solutions (buffer)?
- Weigh the compound
- Dissolve it in a solvent to create a solution that is the same concentration as the intracellular environment
What is a cation?
A positively charge ion
What is an anion?
A negatively charged ion
How do you calculate the molecular mass of methane (CH4)?
Carbons atomic mass = 12
Hydrogens atomic mass = 1
12+1+1+1+1 = 16
What is a mole?
An amount equal to the number of carbon atoms in exactly 12g of the carbon-12 isotope
- One mole contains 6.02214 x 10²³ atoms
What is a solute?
In a solution of 2 substances, that which is present in the smaller amount
What is a solution?
A ‘homogenous mixture’ of two (or more) substances
What is a solvent?
In a solution of 2 substances, that substance which is present in the largest amount
How do you calculate molecular mass?
Add up atomic masses of the elements
How do you calculate the number of moles?
Mass of compound (g) / relative molecular mass of compound
How do you calculate molarity (M)?
Moles of compound / volume (L)
What is the equation used to prepare dilutions from stock solutions?
C1 x V1 = C2 x V2 C = concentration V = volume 1 = stock solution 2 = working solution
What is the equation for percentage solutions?
W/v and v/v
