Solutions and Mixtures

Warm-Up What is a mixture? What is a homogeneous mixture?

Focus Questions What is a solution? What are the differences between unsaturated, saturated, and supersaturated solutions? What are some of the general properties of an acid? What are some of the general properties of a base? What is a neutralization reaction? What is the pH scale? How is pH used to describe the concentration of acids and bases?

Matter Matter can be either a pure substance or a mixture of pure substances. Pure Substance: A pure substance is a material that is homogeneous and has constant properties throughout the sample. (Elements and compounds) Examples: water, diamond, gold, table salt (sodium chloride), ethanol Mixtures There are two types of mixtures

Types of heterogeneous mixtures: Heterogeneous- a mixture that is not uniform in composition –the parts in the mixture can be separated from one another. Types of heterogeneous mixtures: Suspension- a mixture in which the particles settle out when the mixture is allowed to stand. Examples pond water, fruit salad colloid- a mixture consisting of tiny particles that are smaller than suspension but larger than solution particles. The particles will scatter light when it passes through. Emulsion- a colloid in which the liquids do not mix are spread throughout one another. Examples: mayonnaise, peanut butter

Homogeneous mixture-a mixture that is uniform in composition throughout – the parts cannot be separated from one another. Another name for a homogeneous mixture is a solution

Solutions Solution: A type of homogeneous mixture formed when one substance dissolves in another. There are two parts to a solution Solute – the substance that is dissolved. Solvent – the substance that causes the other to dissolve. (Water is usually the solvent.) Example: Lemonade What part of the lemonade is the solute? lemon juice and sugar What part of the lemonade is the solvent? water

Solubility Solubility: The maximum amount of a solute that can be dissolved in a given amount of solvent at a given temperature. Soluble – anything that dissolves in another substance. Ex: Salt is soluble in water. Insoluble – anything that does not dissolve in another substance. Ex: Oil is insoluble in water.

What affects solubility 1. Temperature- Increase temperature, increase solubility. The molecules move faster at higher temperature causing more collisions therefore dissolving faster. 2. Stirring Stirring brings more solute into contact with solvent, therefore increasing solubility 3. Crystal Size Smaller crystals increase surface area. More solvent can come into contact with solute therefore increasing solubility.

Conductivity Conductivity is the measure of a solution’s ability to conduct electricity. The conductivity gives important clues as to the type of solute dissolved. In aqueous (waterbased) solutions, dissolved ionic compounds yield solutions with high conductivity. All of these solutions are considered strong electrolytes. Solutions with low conductivity are called weak electrolytes. Solutions made from covalent compounds have zero conductivity since they dissolve as molecules, not ions. These substances are known as nonelectrolytes.

Concentration Not all solutions have all of the solute that can be dissolved. A concentrated solution has a large amount of solute. A dilute solution has a small amount of solute.

How much can dissolve? If you continue adding sugar to lemonade, eventually the point is reached when no more sugar dissolves and the excess granules sink to the bottom of the glass.

Types of Solubility Unsaturated – more solute can be dissolved in the solvent Saturated – no more solute can be dissolved in the solvent at the current temperature. Generally, as the temperature of a liquid solvent increases, the amount of solid solute that can dissolve in it also increases.

Types of Solubility Supersaturated –contains more solute than a saturated solution at the same temperature. Ex: Rock Candy is made in this way.

Types of Solubility Solubility Curve Each line on the graph is called a solubility curve for a particular substance. You can use a solubility curve to figure out how much solute will dissolve at any temperature given on the graph.

Warm-Up 1. A(n) __________ solution is any solution that can dissolve more solute at a given temperature. A. electrolyte B. saturated C. supersaturated D. unsaturated The answer is D. A saturated solution contains all the solute it can hold at that temperature, but an unsaturated solution can hold additional solute.

Warm-Up 2. What is a solubility curve used for? Answer: You can use a solubility curve to figure out how much solute will dissolve at any temperature given on the graph.

Warm-Up 3. The substance being dissolved in a solution is the __________. A. aqueous phase B. media C. solute D. solvent Answer is C. The solute dissolves into the solvent

Acids An acid is defined by Arrhenius as a substance that dissociates to produce hydrogen ions (H+) in a water solution. HCl → H++ Cl-

Properties of Acids Contains hydrogen Taste sour Reacts with metals to form hydrogen gas Reacts with carbonates to form carbon dioxide, water and a salt Corrode metals Electrolytes pH is less than 7 Turns blue litmus paper to red Mg + 2HCl  MgCl2 + H2 Na2CO3 + 2HCl  CO2 + H2O + 2NaCl Conducts Electricity

ACIDS HCl (hydrochloric acid) - gastric juice H2SO4 (sulfuric acid) - fertilizer, car batteries HC2H3O2 (acetic acid) - vinegar HNO3 (nitric acid) - fertilizers H3C6H5O7 (citric acid) – fruits Other common uses: dyes, paints, food preservation & preparation

Bases or Alkaline NaOH → Na+ + OH- A base is defined by Arrhenius as a substance that produces hydroxide ions OH- in a water solution. NaOH → Na+ + OH-

Properties of Bases Contains OH- Taste bitter Electrolytes Feel soapy, slippery pH greater than 7 Turns red litmus paper to blue Reacts with fats/oils to produce soaps Conducts Electricity

BASES NaOH - lye, drain and oven cleaner Mg(OH)2 - laxative, antacid, milk of magnesia NaHCO3 – cooking, antacid KOH – batteries, biodiesel, soaps Ca(OH)2 – cement Ba(OH)2 – waste water treatment NH4OH – food processing

Common Bases

Warm-Up - Write the questions 1. The pH of an acidic solution is a. Less than 0. c. Less than 7. b. Greater than 14. d. Greater than 7. 2. A solution whose pH is 7 a. Is acidic. c. Is neutral. b. Is basic. d. Is none of the others. 3. Solubility is the _____ amount of a _____ that can be dissolved in a given amount of ______ at a given temperature. a. Least, solute, solvent b. Max, solute, solvent c. Least, solvent, solute d. Max, solvent, solute

Warm-Up In order for a solution to form, one substance must dissolve in another. the solvent must be water. a solid must dissolve in a liquid. a gas must dissolve in a liquid. A student dissolved equal amounts of salt in equal amounts of warm water, room-temperature water, and ice water. Which of the following is true? The salt dissolved most quickly in the warm water. The salt dissolved most quickly in the room-temperature water. The salt dissolved most quickly in the ice water. none of the above

pH Scale pH The pH scale is used to determine how acidic or basic a solution is. measured with a pH meter or an indicator with a wide color range. (Litmus Paper) Ranges from 0 to 14 7 is neutral

Common pH Substances

Neutralization Reaction Note: A salt is an ionic compound Reaction of acid and a base forms a salt and water – ALWAYS NaOH + HCl  NaCl + H2O Acid? Base? Salt? HCl NaOH NaCl

Neutralization Reaction 2HNO3+ Ba(OH)2  H2O + Ba(NO3) Acid? Base? Salt? H3PO4 NaOH Na3PO4

Neutralization Reaction 2LiOH + H2SO4  2H2O + Li2SO4 2HClO4 + Ca(OH)2  Ca(ClO4)2 + 2 H2O KOH + HNO3  H2O + KNO3 H3PO4 + NaOH  H2O + Na3PO4

Solutions, Acids, & Bases Review

Review The substance being dissolved is called _________. The substance doing the dissolving is called __________. A solution is a ______________ mixture. A solution that can dissolve more. _________ A solution that can dissolved no more. ___________ A solution that has dissolved more than normal. ________________

Review Substances that in solutions have H+ (hydrogen) ions are… Acids produce what in water solution? The acid in oranges. The acids in fertilizers. The acid in your stomach. Solutions that have OH- ions are Bases produce what in solution? (name)

Review Base that is in batteries Base in milk of magnesia Bases have a ______feel and ________ taste. Acids have a _______ taste. Acids and bases are both corrosive and react with indicators to produce a _______ change. Both produce ions in water and are therefore _____________.

Review What measures how acidic or basic a substance is? pH measures 1 on the pH scale indicates a ________ acid 7 indicates a substance is________ and 14 indicates a _________ base. A reaction of an acid and a base is what type of reaction? What is formed when an acid and base are combined?

Warm-Up What is nitric acid used for? Hydrochloric Acid is your gastric juice in your stomach… what does it help your body do? Arrhenius defines an acid as something that…..

Warm-Up What is the difference between saturated, unsaturated, & supersaturated? What can we do with a solubility curve? If something is insoluble, what does that mean??

Warm-Up What is the formula for hydrochloric acid? If I produce a hydroxide ion, what am I? I have a bitter taste. What is the formula for magnesium hydroxide? And is it an acid or a base? If I can hold more solute, I am called…

Warm-Up What is the formula for sulfuric acid? If I produce a hydrogen ion, what am I? I have a sour taste. What is the formula for lithium hydroxide? And is it an acid or a base? If I have too much solute, I am called…