Characteristics of States of Matter
What happens to the pressure of a gas when its volume doubles?
Pressure halves.
Gold
Element
Describe one way to separate a mixture of sand and cork.
Utilize their differing densities; put the mixture in water to let the cork float while the sand sinks.
True or False: Elements are the purest kinds of pure substances.
Truuuuuuuuuuuuuuuue
A gas with a volume of 5.0 L and a temperature of 25 degrees Celsius is compressed to a volume of 2.5 L. What is the new temperature of the gas?
5.0 / 298.15 = 2.5 / T2
T2 = 149 K
What is the combined gas law?
Bonus: what scale must you always convert temperature to?
P1V1/T1 = P2V2/T2
Temperature must always be in Kelvin for gas law calculations!
O2 (oxygen)
Element
Describe the intermolecular forces of a substance with a high boiling point.
IMFs are strong; the substance's particles are very attracted to each other and want to stick together, which makes the boiling point very high (lots of heat energy must be input in order for the substance to become a gas)
True or false: Homogeneous mixtures cannot be separated by physical means.
False: all mixtures can be separated by physical means! Ex: salt water can have salt and water separated by boiling away the water.
What is the molar mass of HNO3?
63.01 g/mol
What does it mean that water's solid-liquid phase diagram line has a negative slope?
When you apply pressure to a solid, you can convert it into a liquid. Typically, adding pressure should have the opposite effect because typically, solids are denser than liquids, so compressing a solid will only make the object more solid.
Coffee with Milk
Mixture (Homogeneous)
Name one intensive property and one extensive property
Intensive: property that does not depend on the amount of matter in a sample, like color, boiling point, temperature, etc.
Extensive: property that depends on the amount of matter in a sample, like volume, mass, etc.
True or false? The elements within compounds cannot be separated by physical means.
True! These elements can only be separated by chemical means.
The empirical formula of a sugar is CH2O. The molar mass of the molecular formula is 180 g/mol. What is the molecular formula?
C6H12O6.
Draw the atom-level view of a gas and list several characteristics of gas particles on a molecular level according to the Kinetic Molecular Theory of Gases.
Gas particles do not interact with one another.
The volume of gas particles is negligible compared to the volume of its container.
Gas molecules move in random motion that follow the laws of Newtonian motion.
Hot Cocoa with Marshmallows
Mixture (Heterogeneous)
Describe the physical property that causes a heterogeneous mixture when oil spills occur. Bonus: identify the formula for this physical property.
Density
Density = Mass / Volume
Name an example of a physical change.
Phase changes (melting, boiling, condensing...)
These are reversible changes!
The density of ethanol is 0.789 g/mL at 20 degrees Celsius. Find the mass of a sample of ethanol that has a volume of 150.0 mL at this temperature.
Density = mass/volume
0.789 g/mL = (mass)/(150.0mL)
mass = 0.789*150 = 118g
Draw a heating curve with y-axis being temperature.
Label: solid phase, liquid phase, gas phase, boiling point, melting point, boiling, melting, freezing, condensing.
Does your drawing have plateaus to show boiling point and melting point?
Does your drawing have all the arrows (phase changes) properly labeled?
Table Salt
Compound
Automobile batteries are filled with a solution of sulfuric acid that has a density of 1.285 g/mL. The solution used to fill the battery is 38% sulfuric acid by mass. How many grams of sulfuric acid are present in 500 mL of battery acid?
244.15 g
Name an example of a chemical change
Burning, adding acid, rusting...
Irreversible changes!
A piece of iron ore is found to have a compound containing 72.3% iron and 27.7% oxygen. What is its empirical formula?
Fe3O4