Solutions

Sugar in water Oxygen in water Air Dental fillings Saline

Solutions
A solution A homogeneous mixture of two or more .

Components in a solution

A solution consists of two component types. Solvent: component in the greater extent Solute: component in the lesser extent (You may have more than one.)

Properties of solution

Characteristics of a solution:4The solute can’t be filtered out.4The solute always stays mixed.4Particles are always in motion.4Volumes may not be additive.4A solution will have different properties than the solvent.

Physical states of solutions

Solutions can exist in any of the three states. Solid solutions dental fillings, 14K gold, sterling silver Liquid solutions saline, vodka, vinegar, sugar water Gas solutions the atmosphere, anesthesia gases

Solubility

A measure of how much of a solute can be dissolved in a solvent. Common unit: grams of solute / 100 g of water, at given T. Factors affecting solubility Temperature: usually the higher T, the higher the solubility, except for gases. Pressure: (mostly for gases), the higher the pressure the higher the solubility. Polarity (similarity in charges). Like dissolves like.

Solubility of some substances

Temperature Solubility Substance oC g/100 ml water NaCl (s) 100 39.12 PbCl2 (s) 100 3.34 AgCl (s) 100 0.0021 CH3CH2OH (l) 0 - 100 infinity CH3CH2OCH2CH3 (l) 15 8.43 O2 (g) 60 0.0023 CO2 (g) 40 0.097 SO2 (g) 40 5.41

Saturation

When a solution contains as much solute as it can at a given temperature. It’s saturated.Unsaturated Can still dissolve more.Saturated Have dissolved all you can.Supersaturated Temporarily have dissolved too much.Precipitate Excess solute that falls out of solution.

Properties ofaqueous solutions

There are two general classes of solutes. Electrolytic (electrolytes) conduct electricity may be strong or weak . Nonelectrolytic (non electrolytes) do not conduct electricity

Dissolving ionic compounds

When an ionic solid dissolves in water, the solvent removes ions from the crystal.

Dissolving covalent compounds

Covalent compounds do not dissociate.

Concentration of solutions

We need a way to tell how much solute is in a solution - concentration. There are many systems - we will cover four. Mass / volume percent Volume / volume percent Mass / Mass percent Molarity Molality Molar fraction Parts per million

Mass/Volume %

Mass/Volume % =
Mass solute (g) Total Volume (mL
x 100
If 5 grams of NaCl is dissolved in water to make 200 ml of solution, what is the concentration? 5 g / 200 ml * 100 = 2.5 wt/v% Saline is a 0.9 wt/v% solution of NaCl in water.
use g and ml

Volume/Volume %

Volume/Volume % =
Volume Solute Total Volume
x 100
If 10 ml of alcohol is dissolved in water to make 200 ml of solution, what is the concentration? 10 ml / 200 ml * 100 = 5 V/V% Alcohol in wine is measured as a V/V%.
Use the same units for both

Mass/Mass %

Mass/Mass % =
Mass Solute Total Mass
x 100
If a ham contained 5 grams of fat in 200 g of ham, what is the % wt/wt? 5 g / 200g * 100 = 2.5 wt/wt% On the label, it would say 97.5 % fat free.
Use the same units for both

Molarity

M =
moles solute mol liters of solution L
=
The most important concentration unit in chemistry. Most solution concentrations are expressed as Molarity (M).

MOLARITY

What is moles? Amount of matter expressed in grams. 1 mol of O2 has a mass of 32 g. 1 mol of sodium has a mass of 23 g. 1 mol of H2O has a mass of 18 g. Grams of the substance (g) moles (n) = molar mass (g/mol)


To find the molar mass of a compound the atomic mass from the periodic table is needed. Examples: O = 16, Na = 23, Cl = 35, N = 14. What is the molar mass of NaCl? Ans. Na = 1 x 23 = 23 Cl = 1 x 35 = 35 NaCl = 58 g/mol What is the molar mass of N2O5? Ans. N = 2 x 14 = 28 O = 5 x 16 = 80 N2O5 = 108 g/mol

D I L U T I O N

Once you have a solution, it can be diluted by adding more solvent. This is also important for materials only available as solutions.
1 liter NaCL 1M.
120 ml NaCl 1M.
1 L NaCl ??M.
Solution 1
Solution 2
+ Water =

Dilution

In order to find the new concentration we use the following formula: C1V1 = C2V2 1 = initial 2 = final Any volume or concentration unit can be used as long as you use the same units on both sides of the equation. Calculate the concentration of solution 2 1 M x 120 mL = C2 x 1000 mL

moles of solute kg of solvent

m =
5 g of KI is dissolved in 250 mL of water. Density of water = 0.987 gcm-3. What is the molality of the solution?

n1n1 + n2 + … nn X1 =

What is the molar fraction of nitrogen in a mixture of 8g of nitrogen, 10 g of oxygen and 20 g of CO2?

mg of solute Liter of solution.

ppm =
How much Pb ions are contained in 1 L solution 8 ppm?