Chemistry 1 Chapter 2 Matter & Change

Mass – (g) amount of matter in an object Density Mass – (g) amount of matter in an object Volume – (mL) amount of space occupied by an object Density – (g/mL) a ratio of mass to volume

m D = Formula: Rewrite this formula to solve for m & v! What is the unit for Density???? Remember: A material has the same density no matter how big or small it is!

Example: A piece of metal has a volume of 4.70 mL and a mass of 57.3 g. What is the density? M = 57.3 g V = 4.70 mL D = M / V D = 57.3 g / 4.70 mL D = 12.19148936 g/mL D = 12.2 g/mL

Intensive vs. Extensive Intensive Properties – Do NOT depend on amount Examples: density Extensive Properties – Depends on amount Examples: Mass, volume

Problem A piece of copper has a mass of 57. 54 g. It is 9 Problem A piece of copper has a mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cm3). M V D

Strategy 1. Get dimensions in common units. 2. Calculate volume in cubic centimeters. 3. Calculate the density.

Learning Check Osmium is a very dense metal. What is its density in g/cm3 if 50.00 g of the metal occupies a volume of 2.22cm3? 1) 2.25 g/cm3 2) 22.5 g/cm3 3) 111 g/cm3

Volume Displacement 25 mL A solid displaces a matching volume of water when the solid is placed in water. 33 mL 25 mL

Learning Check What is the density (g/cm3) of 48 g of a metal if the metal raises the level of water in a graduated cylinder from 25 mL to 33 mL? 1) 0.2 g/ cm3 2) 6 g/cm3 3) 252 g/cm3 33 mL 25 mL

Learning Check Which diagram represents the liquid layers in the cylinder? (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) 2) 3) K V W K V W W V K

Solution (K) Karo syrup (1.4 g/mL), (V) vegetable oil (0.91 g/mL,) (W) water (1.0 g/mL) 1) V W K

Learning Check The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? 1) 0.614 kg 2) 614 kg 3) 1.25 kg

Learning Check If blood has a density of 1.05 g/mL, how many liters of blood are donated if 575 g of blood are given? 1) 0.548 L 2) 1.25 L 3) 1.83 L

Graphs of density and volume can be used to find the density of a substance. The slope of the line formed when mass and volume are plotted is the density. Remember “rise over run”.

Scientific Method 5 Steps: 1. Problem 2. Hypothesis 3. Experiment 4. Observations & Data 5. Conclusion 16

1) Problem - “What’s wrong?” 17

2) Hypothesis - “Educated Guess” predict what will happen Based on prior knowledge 18

3) Experiment - Test your hypothesis a) Control Group – stays the same, used for comparison b) Variable Group – what you manipulate that changes 19

1. Independent Variable – what the experimenter (I) changes. 2. Dependent Variable – what is observed/measured. The dependent variable depends on the independent variable The independent variable is what I change!!! 20

3. Control Variables – all other variables that are kept constant. Remember, a good experiment only has two variables that change (independent and dependent). All the rest of the variables must be the same. 21

when graphing… 22

4) Observations & Data collection 23

5) Conclusion - - Based on observations Might support hypothesis! 24

What’s the MATTER? Matter Mass is defined as anything that has mass and takes up space. Mass is the amount of matter an object contains.

A substance is matter that has uniform and definite composition. Pure substances contain only one kind of matter. NaCl Cr Element Compound

Physical Property is a quality or a condition of a substance that can be observed or measured without changing the substance’s composition. Color Size Hardness Density Shape

States of Matter Solid Liquid Gas Name examples of each…

Phases of Matter Solid Liquid Gas

Change in matter without changing the chemical composition. Physical Change Change in matter without changing the chemical composition. Examples: Boiling Freezing Melting Condensing Breaking Splitting Cracking Grinding Cutting Crushing Bending

- Chemical Change – one or more substances changing into a new substance. Signs of a chemical change: 1. Bubbling 2. Change in Temp 3. Color Change 4. Change in Smell

2.2 Mixture Heterogeneous a physical blend of two or more substances. not uniform in composition Examples: Muddy Water Chocolate-Chip Cookie Salad

Solutions are homogeneous mixtures. They consist of one phase. completely uniform in composition Examples: Milk Salt water Solutions are homogeneous mixtures. They consist of one phase.

Phase any part of a system with uniform composition and properties. Heterogeneous mixtures consist of two or more phases. Liquids can be separated by distillation. One liquid is boiled then cooled so it will condense again into a liquid.

2.3 Element Examples: Al C Hg The simplest form of matter that can exist under normal laboratory conditions. Examples: Al C Hg

Compound Examples: AlCl3 NaCl H2CO3 CH3OH A substance that can be separated into simpler substances only by chemical means. Examples: AlCl3 NaCl H2CO3 CH3OH

Classify the following as an element, compound or mixture: C12H22O11 Table sugar Water Iron Vegetable Soup Salt water O2 CaCO3 Air Compound Element Mixture

mass of reactants = mass of products 2.4 Law of Conservation of Mass Mass is neither created nor destroyed in chemical reactions. mass of reactants = mass of products In a chemical reaction, the numbers and kinds of atoms present in the products are the same as those present in the reactants.

In a Chemical reaction two or more substances change into new substances. Reactants  Products Example: Li + KCl  LiCl + K