Matter & Energy Key vocabulary Chemistry – the study of matter Matter – (1) Anything which has mass and takes up space (2) Anything with the property of inertia Inertia – the tendency to resist a change in motion.

PHYSICAL AND CHEMICAL CHANGES Laws of Conservation… Law of Conservation of Matter – matter cannot be created nor destroyed, but may change form. Law of Conservation of Energy – energy cannot be created nor destroyed, but may change form. THESE TWO LAWS ARE IN EFFECT IN ALL PHYSICAL AND CHEMICAL CHANGES

Laws of Conservation… Law of Conservation of Mass-Energy – the total sum of mass and energy in the universe is constant. Matter can be converted to an equal amount of energy and vice versa according to E=mc2. THIS LAW REPLACES THE PREVIOUS TWO LAWS IN NUCLEAR CHANGES

Universe Energy Matter Kinetic Potential Mixture Substance KE = ½ mv2 Energy of Motion Stored Energy KE = ½ mv2

Key Vocabulary Energy – the ability to do work Substance – matter with fixed composition Mixture – two or more substances with variable composition.

Universe Energy Matter Kinetic Potential Mixture Atom Substance Heterogeneous Homogeneous (uniform) Homogeneous (identical) Energy of Motion Stored Energy KE = ½ mv2 Element Compound Solution Atom Molecule Symbol Formula

Key Vocabulary Element – matter made of one type of atom Compound – two or more elements combined in a fixed ratio Solution – two or more substances uniformly mixed (a homogeneous mixture)

Universe Energy Matter Kinetic Potential Mixture gold iron rust Atom Substance Mixture Heterogeneous Homogeneous (uniform) Homogeneous (identical) Energy of Motion Stored Energy KE = ½ mv2 Mixture Element Compound Solution Suspension gold iron methane rust Atom Molecule Colloid neon zinc salt water Symbol Formula

Key Vocabulary Mixture – This term will be used from now on to refer to a Heterogeneous mixture. Suspension – special type of mixture that appears to the naked eye as a solution, but has particles that will settle out over time (Tyndall Effect – a suspension will scatter light from a beam travelling through it, but a solution will not. DEMO) Colloid– like a suspension, but with smaller particles which will not settle out over time (gels, creams and pastes fall into this category.)

Key Vocabulary Phase – a region with a uniform set of properties (Elements, compounds and solutions contain only one phase, but mixtures contain at least two phases) Interface – a boundary between two phases

Key vocabulary Material – any type of matter – includes both substances and mixtures. Mixing – jumbling two or more materials together. This is a physical change which involves no breaking or forming of bonds. Combining – chemical bonding together of two or more substances in a specific ratio.

Mixing vs. Combining Q: What do you get when you mix hydrogen and oxygen? A: You get a MIXTURE of hydrogen and oxygen.

Mixing vs. Combining Q: What do you get when you COMBINE hydrogen and oxygen? A: Water!!

Classifying Changes… Physical Change – Same stuff, different form Ex: cutting, folding, tearing, crushing, melting, boiling, mixing, pulverizing, etc., Chemical Change – At least one new substance is formed Ex: burning, fermenting, reacting, oxidizing, rusting, etc.,

Classifying Properties… DEFINE… Physical Properties Chemical Properties Intensive Properties Extensive Properties

Classifying Properties… Properties may be classified as chemical or physical. Properties may ALSO be classified as intensive or extensive.

Classifying Properties… A particular property may be… …physical AND intensive, …physical AND extensive, …chemical AND intensive, or …chemical AND extensive

Intensive vs. Extensive PROPERTIES Intensive Properties are NOT dependent on the amount, only on the type of material. Ex: color, texture, conductivity, malleability, etc., Extensive Properties depend on the amount of the material present. Ex: mass, volume, length, moles, etc.,

Intensive or Extensive? volume extensive height extensive texture intensive color intensive density intensive

Physical vs. Chemical PROPERTIES Physical Property – any characteristic that can be observed without changing a substance into another substance. Ex: color, mass, volume, density, conductivity, temperature, malleability, etc., Chemical Property – any characteristic that cannot be observed without changing a substance into another substance. Ex: flammability, reactivity (or stability), corrosiveness, etc.,

Chemical or Physical? mass physical flammability chemical tarnishes solubility physical density physical

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(*Usually in the form of HEAT in chemistry!) What is calorimetry? -metry means… …measurement of Calori- means… …energy*. (*Usually in the form of HEAT in chemistry!)

Heat is a total quantity of energy. What is HEAT? HEAT ≠ TEMPERATURE!!! Heat is a total quantity of energy. Temperature is an indicator of the AVERAGE kinetic energy of the atoms or molecules in a system.

So how do we “measure” HEAT? Heat is not measured directly, it is calculated by taking into account 3 factors… …the temperature change of a material, …the mass of the material, and… …the ability of the material to absorb heat (or energy).

So how do we “measure” HEAT? These 3 factors are combined to form the equation; q = mcDt* where q = heat (some sources use H instead of q) m = mass c = specific heat capacity (defined on next slide, some sources use s instead of c) and Dt = change in temperature *(H=mcDt, q=msDt, H=msDt are all the same equation)

Specific Heat Capacity is… A physical constant which quantifies the ability of a substance to absorb energy. The amount of energy needed to raise the temperature of one gram of a substance by one C°. (ex. cH2O=4.184 J/gC°)

Let’s talk about “D” Fat Albert wants to become “Fit” Albert. After dieting for a few weeks, Albert dropped from 420 lbs. to 372 lbs. What was his change in weight? How much weight did he lose?

Let’s talk about “D” You check your bank account balance at the beginning of the month – you have $500. At the end of the month, you have $300. What was the change in your account? How much money did you withdraw?

Let’s talk about “D” NORMALLY… Dx = final x – initial x HOWEVER, if we are calculating an amount LOST or SPENT, we switch this around to avoid a double negative. (Negative heat lost would actually mean heat gained, right?)

Example #1 – Calculate Heat How much energy is needed to heat 12.76 g of iron from 25.0°C to 99.8°C? (ciron=0.4494 J/gC°) Example #1 – Calculate Heat

Calorimetry and the Law of Heat Exchange Review: The Law of Conservation of Energy The Law of Heat Exchange is a specific application of the Law of Conservation of Energy; qlost = qgained Although the heat lost by the hot object may go several places, if the hot object is placed in water, virtually all of its heat loss is absorbed by the water.

If a 37. 28 g piece of metal is heated to 95 If a 37.28 g piece of metal is heated to 95.0°C and then dropped into 65.0 mL of water at 26.1°C and the final temperature of the system is 26.8°C, what is the specific heat capacity of the metal? Example #2 – Find “c”

Example #3 – Predict final temp. If a 28.74 g piece of aluminum is heated to 95.0°C and dropped into 125.0 mL of water at 24.6°C, what will be the final temperature of the system? (CAluminum=0.9025 J/gC°) Example #3 – Predict final temp.