Unit A: Introduction: Matter and Measurement

Unit A: Introduction:Matter and Measurement Chapter 1 Interactive Notes

Select the phase and properties that are NOT correct. Select all that apply. • Solid - definite shape, constant density • Gas - compressible, fluid • Vapor - definite volume, indefinite shape • Solid - rigid, incompressible • Liquid - definite volume, indefinite shape • Gas - variable density, fills its container • Liquid - compressible, fluid • All are correct.

Which of the properties listed below are intensive?Select all that apply. • Mass • Weight • Temperature • Volume • Density • Length • Heat capacity • Specific heat capacity • Melting Point

Physical Properties • An extensive property will change when the size of the sample changes. • Mass, volume, weight, length, and heat capacity are extensive properties. • An intensive property does not depend on sample size and is often (though not always) uniqueto that type of matter (sometimes called a characteristic property). • Density, melting point, specific heat capacity, color, and temperature are intensive properties.

Write a short question that would be suitable for the pink box.

Write a short question that would be suitable for the blue box.

Write a short question that would be suitable for the green box.

Same Scheme, Arranged Differently

B A C D Which box(es) contain(s) only elements? Select as many as appropriate.

B A C D Which box(es) contain(s) only elements? A, in which the particles are atoms B, in which the particles are molecules.

B A C D Which box(es) contain(s) a pure substance?

B A C D Which box(es) contain(s) a pure substance? A and B which are elements and C which is a compound. Only D is a mixture of both elements and a compound and the particles are both atoms and molecules.

Which of the following techniques are useful for physical separation of homogenous mixtures?Select all that apply. • Distillation • Mass to mole conversion • Combustion • Filtration • Chromatography • Vector analysis • Centrifuging • Neutralization • Electrolysis

Distillation - The physical property(ies) of substances that makes distillation an effective separation technique is Select all that apply. • melting point • boiling point • mass • solubility • temperature • particle size • polarity • specific heat capacity • volume

Distillation - The physical property(ies) of substances that makes distillation an effective separation technique is Select all that apply. miscible- the property of liquids to mix in all proportions forming a homogeneous solution. • Distillation is generally used to separate two miscibleliquids, not usually a nonvolatile solid dissolved in a liquid. • melting point • boiling point • mass • solubility • temperature • certainly temperature is important in this procedure, but all materials would be at the same temperature at any given time until running through the condenser. • particle size • polarity • You can argue that these two properties influence boiling point... but these would not be the primary property causing the separation. • specific heat capacity • volume

Filter paper Perforated platform to hold filter paper (same exact size as platform) Plastic Buchner funnel Rubber stopper Hose to vacuum pump Side-arm flask Effluent Gravity & Vacuum Filtration Gravity filtration with fluted filter paper. Büchner Funnel Set-up for vacuum filtration.

Filtration - The physical property(ies) of substances that makes filtration an effective separation technique is Select all that apply. • melting point • boiling point • volume • solubility • temperature • particle size • polarity • specific heat capacity • density

Filtration - The physical property(ies) of substances that makes filtration an effective separation technique is Select all that apply. • melting point • boiling point • volume • solubility • soluble substances will sometimes ionize to smaller particles or at the very least “unclump” making solubility play a roll. • temperature • particle size • ultimately what fits through the holes of the filter and what does not, depends on particle size. • polarity • specific heat capacity • density

Paper Chromatography

Chromatography - The physical property(ies) of substances that makes chromatography an effective separation technique is Select all that apply. • melting point • boiling point • volume • solubility • temperature • particle size • polarity • specific heat capacity • density

Chromatography - The physical property(ies) of substances that makes chromatography an effective separation technique is Select all that apply. • melting point • boiling point • volume • solubility • certainly the substances to be separated must be soluble in the mobile phase for any separation to occur. • temperature • particle size we learned earlier that the size plays a role in its mobility, however at the time we didn’t know about polarity which is MORE important • polarity • the polarity of the molecules to be separated affect their “stickiness” to each other and to the solvent, affect the rate (and resulting distance) at which they will travel across the stationary phase (aka medium) • specific heat capacity • density

Centrifuging - The physical property(ies) of substances that makes centrifuging an effective separation technique is Select all that apply. • melting point • boiling point • volume • solubility • temperature • particle size • polarity • specific heat capacity • density

Centrifuging - The physical property(ies) of substances that makes centrifuging an effective separation technique is Select all that apply. • melting point • boiling point • volume • solubility • temperature • particle size • the larger particle size may play a role • polarity • specific heat capacity • density • the greater inertia of the more dense particles make them tend to collect near the outside of the “swing”

Techniques for Physical Separation • Distillation: Using varied boiling points to remove the more volatile solvent from solution, leaving the solute. • Filtration: Using a semi-permeable barrier to block the passage of larger particles (like a strainer). • Chromatography: Some substances will be “dragged” by a “sticky” solvent faster than others, separating substances as a function of time. • Centrifuging: A centrifuge is used to rapidly separate dense substances from less dense substances. It can also be used for gases.

This diagram best illustrates • the Law of Constant Composition. • the Law of Conservation of Mass. • the First Law of Thermodynamics • the Law of Definite Proportions • the Law of Mass Action

The Various Ways You Can State the Law of Conservation of Mass • There is no detectable change in the total mass of materials when they react chemically to form new materials. • The mass of the products will equal the mass of the reactants in a chemical reaction. • During a chemical reaction, matter is neither created nor destroyed. • The mass of what you start with is what you’ll finish with in a chemical reaction.

This experiment might be used for • the Law of Constant Composition. • the Law of Conservation of Mass. • the First Law of Thermodynamics • the Law of Definite Proportions • the Law of Multiple Proportions • measuring % of the reacting part of air • the Law of Mass Action

The Various Ways You could State the Law of Constant Composition(aka) Law of Definite Proportions • Elements combine in definitemassratios to form compounds. • A given chemical compound always contains the sameproportion by mass of its constituent elements. • The relativemass of each element in a particular compound is always the same, regardless of preparation or source.

Law of Constant Composition(aka) Law of Definite Proportions

What is the Law of Multiple Proportions? (from John Dalton) • If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. • for instance; A fixed mass of carbon, say 10.0 grams, may react with 13.3 grams of oxygen to produce one oxide, or with 26.6 grams of oxygen to produce the other.

What is the Law of Multiple Proportions? (from John Dalton) • The ratio of the masses of oxygen that can react with 10.0 grams of carbon is 26.6 : 13.3 ≈ 2:1, a ratio of small whole numbers. • Dalton interpreted this result in his atomic theory by proposing (correctly in this case) that the two oxides have one and two oxygen atoms respectively for each carbon atom. • In modern notation the first is CO (carbon monoxide) and the second is CO2 (carbon dioxide). • The law of multiple proportions is best demonstrated using simple compounds (as opposed to large hydrocarbons.) • John Dalton first expressed this observation in 1804 and published it in 1808.

Nitrogen and Oxygen exhibiting the Law of Multiple Proportions.

What changes in a chemical change that does not change during a physical change? Select all that apply. • color • shape • appearance • identity • temperature • mass

Physical vs Chemical Changes • Physical Changes • Appearances and physical properties may change, but the identities of the chemicals remains the same. • Chemical Changes • Appearances and physical properties are likely to change because the identity of the substances will change. • New substances will be formed.

Which reaction below would best represent the electrolysis of water? • H2O(L) → H2O(g) • H2O → H2 + ½O2 • H2O → H+ + OH− • H2O → 2H + O • H2O → 2H+ + O2−

Chemical Change:Electrolysisof WaterH2O → H2 + ½O2Physical Change:Boiling of waterH2O(L) → H2O(g) 46

Accuracy & PrecisionSignificant Figures • and more...

Which dartboard shows good accuracy? Select all that apply. 1 2 3

Which dartboard shows good accuracy? Select all that apply. • I suppose you could argue that # 2 was also good accuracy if the game you were playing required you to hit that area of the board. I was going on the assumption that the bulls-eye was the point of the game. 1 2 3

“Exactness”, Accuracy, and Precision • “Exactness” • The number of decimal places in the measurement. • Accuracy • How close the value agrees with the accepted value. • Precision • The reproducibility of the values.

Unit A: Introduction: Matter and Measurement