Solutions Chapter 15

Chemcatalyst:___.___ Think back to marking period one and define in your own words the difference between a homogeneous and a heterogeneous mixture?

Mixtures Uniform throughout 1 continual phase HOMOGENEOUS HETEROGENEOUS Uniform throughout 1 continual phase Example: solutions like salt water Not uniform throughout Multiple phases Example: Oil and water

Other Heterogeneous Mixtures: Suspension Colloids Particles are much larger Do not stay suspend indefinitely Particles begin to separate out Multiple phases Example: Clay in water or sand in water Particles are medium-sized Spread out and dispersed Cloudy or milky appearance Examples: Whipped cream, glue, milk, or mayo

Did you know? Colloidal solutions, like fog, disperse or separate light! It is called the Tyndall effect! When light passes through it, the particles reflect or scatter the light in all different directions!

Mini Lab on types

Properties of Solutions Chapter 16

Chemcatalyst: __.__ Predict and explain whether sugar will dissolve faster in iced tea or hot tea. Follow up: Which would dissolve faster cubed sugar or granular sugar?

Solutions, eh? Solutions are homogeneous mixtures! Meaning same throughout  They can be solids, liquids, or gases!

How do I make this said solution…? A solution has a solute and solvent SOLUTE SOLVENT The dissolved particles in a solution is known as a solvent The solute will become dispersed throughout the solvent Can be solids, liquids, or gases The dissolving medium is the solvent The solvent dissolves the solute Can be solids, liquids, or gases

Why do you stir sugar into your tea?

Agitation Stirring or shaking speeds up the solution process More of the solute will be brought into contact with solvent Only affects the time it takes to dissolve, not the amount of solute dissolving Insoluble will always be insoluble

Back to the C.C Hot or cold tea dissolves sugar faster?

Temperature High temperature, more kinetic energy molecules move faster The rapid motion is an increase in collisions between the solvent and the solute http://www.youtube.com/watch?v=cckAwavEKA0

Back to the C.C. follow up Sugar cube or granular sugar dissolves faster?

Particle Size of Solute The smaller the particles, the greater surface area to collide with the solvent The more surface area, more collisions and the faster rate of dissolving

Chemcatalyst __.___ What does it mean if something is soluble? Give an example

Solubility The amount of solute that dissolves in a given quantity of solvent at a given temperature and pressure This amount creates a saturated solution Solubility is expressed in g/100 g H2O

Think about this… Kool aid man, “Ohh yeaa” © What if I put the entire container in? What does it look/taste like if I do not put all of it in?

Supersaturated vs Unsaturated A solution that contains more solute that is able to dissolve Only so much will dissolve, the rest will be solid on the bottom Ex: Adding too much of the Kool Aid powder, rock candy A solution that contains less solute than the saturated solution Ex: Not adding enough Kool Aid Powder

Did you know? Miscible means soluble or the ability to dissolve in one another Example: Water and Ethanol Immiscible means they are insoluble Example: Oil and water

Mini Lab Solution and solubility mini lab Play at end of lab http://www.youtube.com/watch?v=ghKUzh8l_t0

Factors affecting solubility Temperature Pressure In general, the solubility of a solid increases as the solvent is heated In general, the solubility of a gas increases as the solvent is cooled Little effect on the solubility of solids and liquids If the pressure above the liquid increases, the solubility of the gas increases

Henry’s Law At a given temperature, the solubility of a gas in a liquid is proportional to the pressure above the liquid. If the pressure increases, the solubility increases Example: Carbonated soda (CO2)

Chemcatalyst: __.___ What would you need to change? A saturated solution to an unsaturated solution A saturated solution to a supersaturated solution An unsaturated solution to a saturated solution

What is concentration? The measure of the amount of solute that is dissolved in a given solvent Depending on the amount it can be classified as dilute or concentrated

Concentrated solution Concentration Dilute solution Concentrated solution A small amount of solute dissolved Large amounts of solute dissolved *** Only qualitative, not QUANTITATIVE

If that’s qualitative, then how do we measure concentration?

Molarity (M) Molarity is the number of moles dissolved in 1 liter of solution Referred to a molar concentration or solution Units are moles/liter or represented as M (molar) Molarity = Moles of the solute Liters of the solution ** Volume must be in liters

Let’s calculate the molarity together! What is the molarity of a solution that contains 0.70 mol of NaCl in 250. mL? 250. 𝑚𝐿 1 𝑥 1 𝐿 1000𝑚𝐿 =0.250 𝐿 Molarity= 0.70 𝑚𝑜𝑙𝑒𝑠 0.250 𝐿 =2.8 𝑀

Try this one on your own: IV fluid has 0.15 moles of saline solution in it, what would the molarity be for 200. mL? 200. 𝑚𝐿 1 𝑥 1 𝐿 1000𝑚𝐿 =0.200 𝐿 Molarity= 0.15 𝑚𝑜𝑙𝑒𝑠 0.200 𝐿 =.75 𝑀

How do you make a solution? Mini Lab http://www.youtube.com/watch?v=cckAwavEKA0

Reach question! A solution has a volume of 2.0 L and contains 36.0 grams of glucose. If the molar mass of glucose is 180 g/mol, what is the molarity of the solution? 0.10M

Chemcatalyst: __.__ What would the molarity be a solution that has 0.0500 moles of solute and a given volume of 400. mL? Show work with units, try your best with SF 

Dilution 1 is initial conditions( concentrated solution) To create a dilution, the number of moles of solution will be reduced A dilution is created from a concentrated solution We use this equation: M1V1 =M2V2 1 is initial conditions( concentrated solution) 2 is final conditions (dilute “new” conditions)

Let’s do this together! M1V1 =M2V2 (2.00 M) V1= (0.400 M) (100.0 mL) How many mL of 2.00 M MgSO4 solution must be diluted to prepare a 100.0 mL of 0.400 M MgSO4 ? M1= 2.00 M V1= ? mL M2= 0.400 M V2= 100.0 mL M1V1 =M2V2 (2.00 M) V1= (0.400 M) (100.0 mL) V1= 20.0 mL

Try this one on your own! M1V1 =M2V2 (4.00 M) V1= (0.760 M) (250.0 mL) How many mL of a solution of 4.00 M KI are needed to prepare 250.0 mL of 0.760 M KI M1= 4.00 M V1= ? mL M2= 0.760 M V2= 250.0 mL M1V1 =M2V2 (4.00 M) V1= (0.760 M) (250.0 mL) V1= 47.5 mL

Chemcatalyst: __.__ How many moles of ammonium nitrate are in 355 mL of a 0.425 M solution 0.151 mol How many mL of a 1.0 M solution to prepare 250. mL of a 0.20 M solution? 50. mL