Topic 1 Mrs. Kuhn Chemistry Center for Creative Arts

Scientific Method State the problem and observe. Observations may be either qualitative (describing physically observed phenomena) or quantitative (involving numerical measurements). State the problem and observe. Observations may be either qualitative (describing physically observed phenomena) or quantitative (involving numerical measurements). Propose an explanation (aka hypothesis). Propose an explanation (aka hypothesis). Perform experiments to test hypothesis. Results and conclusions may lead to further experimentation. Perform experiments to test hypothesis. Results and conclusions may lead to further experimentation.

States of Matter All matter has two distinct characteristics: mass and volume. All matter has two distinct characteristics: mass and volume. Solids: definite shape and volume. Particles are closely packed and only vibrate in fixed positions. Solids: definite shape and volume. Particles are closely packed and only vibrate in fixed positions. Liquids: indefinite shape and definite volume. Particles in liquid are free to move. Liquids: indefinite shape and definite volume. Particles in liquid are free to move. Gases: No definite shape or volume. Particles are free to move and expand to fill container. Gases: No definite shape or volume. Particles are free to move and expand to fill container.

Properties of Matter Physical Properties Chemical Properties HardnessFlammability Color and Odor Acidity DensityBasicity Boiling/Melting Point Reactivity Solubility

Physical Changes Involve altering shape, size, or state without changing chemical composition. Involve altering shape, size, or state without changing chemical composition. SOLID LIQUID_______________ SOLID LIQUID_______________ GAS LIQUID_______________ GAS LIQUID_______________ SOLID GAS_______________ SOLID GAS_______________ LIQUID SOLID_______________ LIQUID SOLID_______________ GAS SOLID_______________ GAS SOLID_______________ LIQUID GAS_______________ LIQUID GAS_______________

Chemical Changes In chemical changes or reactions, the atoms of a substance are rearranged. The chemical composition of the new substance differ from the original. In chemical changes or reactions, the atoms of a substance are rearranged. The chemical composition of the new substance differ from the original. Examples? Examples?

Heat Transfer When physical or chemical changes produce or absorb heat, the amount of heat involved is calculated using the specific heat capacity of the substance. When physical or chemical changes produce or absorb heat, the amount of heat involved is calculated using the specific heat capacity of the substance. H = m x c x T H = amount of heat change m = mass of substance c = specific heat capacity T = change in temperature in Celsius (determined by subtracting the final temp from the initial temp)

Common Heat Capacities Water (H 2 O) J/g°C Aluminum 0.89 J/g°C Iron 0.45 J/g°C Silver 0.24 J/g°C

Specific Heat Capacity Sample Problems 1. What quantity of energy is required to raise the temperature of 10 grams of water from 15°C to 50°C? 2. A 5.0 gram sample of an iron nail requires 37.75J of energy to change its temperature from 25°C to 32.5°C. Is the nail made of pure iron? Explain.

Density Density is another attribute of matter. Density describes the relationship between a substances mass and its volume. Density is another attribute of matter. Density describes the relationship between a substances mass and its volume. Density = mass/volume Density = mass/volume d = m/v d = g/cm 3 d = g/ml d = m/v d = g/cm 3 d = g/ml

Density practice What is the density of an object if its mass is 124 grams and its volume is 130 mls? What is the density of an object if its mass is 124 grams and its volume is 130 mls? What is the density of a cube if its dimensions are 3cm x 4 cm x 2 cm and its mass is 10.0 g? (Remember: What is the density of a cube if its dimensions are 3cm x 4 cm x 2 cm and its mass is 10.0 g? (Remember: v= l x w x h) v= l x w x h)

Common Densities Water g/cm 3 Gold 19.7g/cm 3 Aluminum 2.7 g/cm 3 Lead 11.3 g/cm 3 Air g/cm 3 Helium g/cm 3