Phy Chem Exam 2

what does concentration reflect

amount of a specific substance contained per unit of amount of the mixture

True or false Volumes are additive

false

the mass of sodium chloride a pt receives after intravenous infusion of 150mL of a 0.9% (m/v) solution can be calculated as

g solute = %concentra/100 X v of solution g solute = 0.9%/100 X 150mL = 1.35g of solute

how do you rearrange the %m/v equation when looking for the solute?

g solute = concentration x mL of solution

What is concentration

intensive property commonly used when working with homogeneous mixtures

for %v/v what is the equation look like and what does it NOT look like

it is =%v/v = v of solute/v of solution X 100 it is NOT = v of solute/ v of solute + v of solution

a normal saline solution for intravenous infusion can be prepared by dissolving 4.5g of sodium chloride in enough water to yield 500mL of solution. What is the % mass-to-volume?

mass of solute / volume of solution X 100 4.5g / 500mL X 100 = 0.9%

what are the 3 ratios used for concentration

mass/mass volume/volume mass/volume or ppm

what does concentration refer to

the amount of one substance contained within a mixture of various substances

True or false Masses are additive

true

which concentration is most common in lab setting?

% M/V

Hyponatremia (low plasma sodium) can be treated in the icu by intravenous infusion of a 3% sodium chloride solution. If you have 6g of sodium chloride, what would be the final volume of solution needed to prepare a 3% (m/v) solution?

%m/v = m of solute / v of solution X 100 3% = 6g / ? X 100 divide both sides by 100 0.03 = 6/? ? = 6/0.03 = 200mL of solution can be made with the solute avaliable

A commercial mouthwash contains 15mL of ethanol for every 250mL of solution. What is the %v/v of ethanol

%v/v = (15mL / 250mL) X 100

what is the equation for mass/mass

(grams solute/grams of solution) X 100%

%m/m = what equation

(mass of solute (g) / volume of solution (mL)) X 100

How many grams of sucrose must be added to 375g of water to prepare a 2.75% solution? 1. What are we looking for in this problem? 2. what is the m/m equation? 3. How do we rearrange the equation to find out amount of solute? 4. solve

1. grams of sucrose (grams of solute) 2. (g solute / g solution) X 100 3. % in g / 100g - % in g then divide the solute g (sucrose) /solvent g (water)X g of water waters will cancel leaving you with g of solute -------------------------------------------------------- solve by noting that 2.75% = 2.75 g of solute out of 100g of solution so... 2.75-100= 97.25 g of water (2.75g sucrose/ 97.25g water) x 375g water = 10.5769231 3 sig figs = 10.6g of sucrose

What must be the final volume of solution if a 6.5% (v/v) of acetic acid in water is being prepared using 25mL of pure acetic acid? 1. What are we looking for 2. what does the equation look like 3. rearrange the problem 4. solve

1. volume of the solution 2. 6.5% = (25mL(solute) / ?) X 100 3. v of solution = (100/%v/v) X V of solute 4. ? = (100/6.5%) X 25mL = 384.615385 2sig fig = 380