Solutions Properties of Water Solutions Predict the water

Solutions Properties of Water Solutions

Predict the % water in the following foods

Predict the % water in the following foods 88% water 94% water 85% water 86% water

Water in the Body water gain liquids 1000 m. L food 1200 m. L cells 300 m. L water loss urine 1500 m. L perspiring 300 m. L exhaling 600 m. L feces 100 m. L Calculate the total water gain and water loss Total ______ m. L

Water l Most common solvent l A polar molecule O a hydrogen bond H +

Hydrogen Bonds Attract Polar Water Molecules

Explore: Surface Tension n Fill a glass to the brim with water n How many pennies can you add to the glass without causing any water to run over? Predict _________ Actual _________ n Explain your results

Explore 1. Place some water on a waxy surface. Why do drops form? 2. Carefully place a needle on the surface of water. Why does it float? What happens if you push it through the water surface? 3. Sprinkle pepper on water. What does it do? Add a drop of soap. What happens?

Surface Tension l Water molecules within water hydrogen bond in all directions l Water molecules at surface cannot hydrogen bond above the surface, pulled inward l Water surface behaves like a thin, elastic membrane or “skin” l Surfactants (detergents) undo hydrogen bonding

Solute and Solvent Solutions are homogeneous mixtures of two or more substances l Solute The substance in the lesser amount l Solvent The substance in the greater amount

Nature of Solutes in Solutions l Spread evenly throughout the solution l Cannot be separated by filtration l Can be separated by evaporation l Not visible, solution appears transparent l May give a color to the solution

Types of Solutions air O 2 gas and N 2 gas/gas gaseosa CO 2 gas in water gas/liquid seawater Na. Cl in water solid/liquid brass copper and zinc solid/solid

Discussion Give examples of some solutions and explain why they are solutions.

Test yourself (1) element (2) compound (3) solution A. water 1 2 3 B. sugar 1 2 3 C. salt water 1 2 3 D. air 1 2 3 E. tea 1 2 3

Answers (1) element (2) compound A. water 2 B. sugar 2 C. salt water 3 D. air 3 E. tea 3 (3) solution

Test yourself Identify the solute and the solvent. A. brass: 20 g zinc + 50 g copper solute = 1) zinc 2) copper solvent = 1) zinc 2) copper B. 100 g H 2 O + 5 g KCl solute = 1) KCl 2) H 2 O solvent = 1) KCl 2) H 2 O

Answers A. brass: 20 g zinc + 50 g copper solute solvent = = 1) zinc 2) copper B. 100 g H 2 O + 5 g KCl solute = 1) KCl solvent = 2) H 2 O

Test yourself Identify the solute in each of the following solutions: A. 2 g sugar (1) + 100 m. L water (2) B. 60. 0 m. L ethyl alcohol(1) and 30. 0 m. L of methyl alcohol (2) C. 55. 0 m. L water (1) and 1. 50 g Na. Cl (2) D. Air: 200 m. L O 2 (1) + 800 m. L N 2 (2)

Answer Identify the solute in each of the following solutions: A. 2 g sugar (1) B. 30. 0 m. L of methyl alcohol (2) C. 50 g Na. Cl (2) D. 200 m. L O 2 (1)

Like dissolves like A ______ solvent such as water is needed to dissolve polar solutes such as sugar and ionic solutes such as Na. Cl. A ______solvent such as hexane (C 6 H 14) is needed to dissolve non-polar solutes such as oil or grease.

Self test Which of the following solutes will dissolve in water? Why? 1) Na 2 SO 4 2) gasoline 3) I 2 4) HCl

Answer Which of the following solutes will dissolve in water? Why? 1) Na 2 SO 4 Yes, polar (ionic) 2) gasoline No, non-polar 3) I 2 No, nonpolar 4) HCl Yes, Polar

Formation of a Solution H 2 O Cl- Na+ Clsolute Na+ H 2 O Cl- Hydration Dissolved solute

Writing An Equation for a Solution When Na. Cl(s) dissolves in water, the reaction can be written as H 2 O Na. Cl(s) solid Na+ (aq) + Cl- (aq) separation of ions in water

Self test Solid Li. Cl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom( -) of water 2) hydrogen atom( +) of water B. The Cl- ions are attracted to the 1) oxygen atom( -) of water 2) hydrogen atom( +) of water

Answer Solid Li. Cl is added to some water. It dissolves because A. The Li+ ions are attracted to the 1) oxygen atom( -) of water B. The Cl- ions are attracted to the 2) hydrogen atom( +) of water

Rate of Solution You are making a chicken stock using an oxo cube. What are some things you can do to make it dissolve faster? l Crush it l Use hot water (increase temperature) l Stir it

Self test You need to dissolve some gelatin in water. Indicate the effect of each of the following on the rate at which the gelatin dissolves as (1) increase, (2) decrease, (3) no change A. ___Heating the water B. ___Using large pieces of gelatin C. ___Stirring the solution

Answer You need to dissolve some gelatin in water. Indicate the effect of each of the following on the rate at which the gelatin dissolves as (1) increase, (2) decrease, (3) no change A. 1 Heating the water B. 2 Using large pieces of gelatin C. 2 Stirring the solution