Mixtures Spring 2011

Compounds Vs. Mixtures Compound Definition: Two or more different elements chemically bonded by a chemical reaction to form a new substance. Examples: NaCl, H2O, CO2 How can they be broken down or separated?: Compounds can only be broken down or separated by chemical means. (it requires a chemical reaction to break them apart).

Compounds Vs. Mixtures Mixtures Definition: a combination of two or more substances that are not chemically combined. Examples: salad, kool-aid, blood, salt water How can they be broken down or separated?: Mixtures can be broken down physically. No chemical reaction is required.

Characteristics of Mixtures No chemical change occurs(the substances keep their identity). B.THE SUBSTANCES CAN BE SEPARATED!!!!!

Atoms vs. Elements vs. Compounds vs. Mixtures

MIXTURES COMPOUNDS Components are elements, compounds or both Components are elements Components keep their original properties Components lose their original properties Separated by physical means Separated by chemical means Formed using any ratio of components (Ex- salad, if you want more lettuce, just add it) Formed using a specific ratio of elements (Ex- water H2O… not H2O2)

Types of Mixtures Heterogeneous- the different substances are visible in the mixture. Homogeneous – The mixture looks the same and has the same characteristics throughout.

Types of Heterogeneous mixtures a. Suspension: mixtures in which particles of a material are dispersed throughout a liquid or gas but are large enough that they settle out.

Types of Homogenous Mixtures Solution: A mixture that looks to be the same but is composed of 2 or more substances appears to be a single substance. Examples: Alloys, soda, salt water, tea.

Types of Homogeneous Mixtures Colloid: a mixtures in which the particles are dispersed (spread) throughout but are not heavy enough to settle out. Examples: Milk, mayonnaise, stick deodorant, shaving cream, and jello are all colloids. Colloids are like a mix between solutions and suspensions

Parts of a Solution Solute: is the substance that is dissolved. Ex. Salt, sugar. Solvent: is the substance in which the solute is dissolved in. Does the dissolving Ex. Water.

Solubility=the ability of an object to dissolve into other substances. Solubility of Solids and Temperature Change: Solubility of solids increases as temperature increases. Solubility of Gases and Temperature Change: Solubility of gases decreases as temperature increases.

Separating Mixtures Suppose you had a mixture of iron nails, salt and water… How would you separate this mixture completely? Based on which physical properties would you base your method on?

Ways Mixtures Can Be Separated Filtration – Used to separate heterogeneous mixtures composed of liquids and solids Using some form of filter to separate particles that won’t dissolve from a liquid. This is good for separating an insoluble solid from a liquid (an insoluble substance does not dissolve in water). EX: sand can be separated from a mixture of sand and water Using filtration

Evaporation – Used when you wish to collect a solute from a solution. Evaporate a LIQUID to leave the SOLID behind.

Separating Mixtures Continued Distillation: the process that separate a mixture based on the boiling points of the components. Used to separate Homogeneous mixtures

Chromatography – used to separate out mixtures of dyes. Shows all the colors used to make certain dyes or pigments ink stain

Acids & Bases

Foldable Instructions Get a piece of paper and fold “hamburger style”. Fold “hamburger style” again. Cut the TOP half of the paper up to the “mountain”. Label one side “ACID” and the other side “BASE”. The inside of the flaps should contain your notes on acids, bases, and the pH scale. Follow along with PowerPoint.

Our Goals for today To determine the difference between Acids & Bases Discuss the importance of studying Acids & Bases Perform an experiment dealing with Acids & Bases

Characteristics Of Acids Acids can be characterized by: A sour taste. Try drinking lemon juice (citric acid) It turns litmus paper red Have a pH from 0-7, the lower the pH number the stronger the acid… They can neutralize (chemical reaction) a base. They are corrosive (eat through things).

Characteristics of Bases A Base is characterized by: A bitter taste. (TUMS) It feels slippery. (Soapy Water) It turns Red Litmus Blue. Have a pH from 7-14, the higher the pH number, the stronger the base. Can neutralize (chemical reaction) an acid.

What is the pH scale? The pH scale measures how acidic or basic a mixture is.

Draw a pH scale in your foldable Draw a pH scale in your foldable. You do NOT have to draw the pictures, but you should include some examples of acids and bases on your scale.

Identifying Acids and Bases Acids have a ph from 0-7 Lower pH value indicates a stronger acid. Bases have a pH from 7-14 Higher pH value indicates a stronger base.

Did we Miss something?? What happens when the pH of a substance is 7? Ans: A pH level of 7 indicates a Neutral Substance i.e: Water! Neutral- is neither an acid nor a base. Neutralization- chemical reaction between an acid and a base to form a neutral substance (salts).

Why Learn about Acids & Bases? What do you think is the pH level of NYC tap water? The pH of a swimming pool must be checked periodically. Why? Is it important for Lakes & Rivers to maintain a certain pH?

Today’s Experiment Test the pH of Pepsi, tap water, and drain cleaner On the back of your foldable copy the chart below to record your observations about acids and bases. GOOD LUCK!!! Substance Color (after dipping) pH Acid/Base/Neutral Pepsi Water Drain Cleaner

Bellringer #1 The smallest part of matter is: a. Cell b. Particle c. Molecule d. Atom To find information about elements: a. Look at a dictionary b. Use a periodic table c. Google them d. Look under a microscope Vocabulary words are: a. Any word you don’t know b. Words that may help me understand a concept better c. Important to all subject areas. d. All of the above.

Bellringer #2 1. A mixture where you can see the individual parts is called a: a. Homogenous mixture b. Solution c. Colloid d. Heterogeneous mixture 2. A mixture where you cannot see the individual parts is called a: b. Suspension c. Heterogeneous mixture d. Compound 3. The main difference between compounds and mixtures is: a. Compounds can be separated but mixtures cannot. b. Compounds do not require a chemical reaction to occur. c. Mixtures can be separated by physical means. d. Mixtures require a chemical reaction.

Bellringer #3 1. A solute is: The liquid that a solid or gas is dissolved into. The solid or gas that is dissolved. Is greater than the solvent. 2. A solvent is: a. The liquid that a solid or gas is dissolved into. b. The solid or gas that dissolved. c. Is less than the solute. 3. A solution is: a. A homogenous mixture b. A mixture with a solute and solvent c. Both A and B

Bellringer #4 1. When you balance chemical equations: a. The atoms are equal on both sides of the equation. b. There are more atoms on the reactant side of the equation. c. There are more atoms on the product side of the equation. Solubility of solids: a. Increases with a decrease in temperature. b. Increases with an increase in temperature. c. Decreases with an increase in temperature. The two main types of mixtures are: a. Heterogeneous and homogenous b. Solutions and suspensions c. Solute and solvent