CH.11 Env. Sci.
The molecules of a gas at room temperature move at about
500m/s
Humidity is a measure of the amount of water vapor in the atmosphere. Why is humidity always very low inside your kitchen freezer?
Because at the cold temperatures of your kitchen freezer, water molecules in the vapor phase are moving relatively slowly, which makes it easier for them to stick to inner surfaces within the freezer or to other water molecules.
The diagram on the far left shows the moving particles of a gaseous material within a rigid container. 1118 Which of the three boxes on the right best represents this material upon the addition of heat?
Box B, because it shows the gas particles moving faster.
The circles in the boxes shown above represent the submicroscopic particles of a material in three phases. 1112
Liquid, solid, and gas.
Oxygen atoms are used to make water molecules. Does this mean that oxygen, O2, and water, H2O, have similar properties?
No, compounds are uniquely different from the elements from which they're made.
If you eat metallic sodium or inhale chlorine gas, you stand a strong chance of dying. Let these two elements react with each other, however, and you can safely sprinkle the compound on your popcorn for better taste. What is going on?
Sodium chloride does not behave like either sodium or chlorine.
Which has stronger attractions among its submicroscopic particles: a solid at 25°C or a gas at 25°C?
The attractions among the submicroscopic particles of the solid must be stronger than the attractions among the particles of the gas.
How is a physical change different from a chemical change?
The chemical identity of a substance is not altered during a physical change.
What chemical change occurs when a wax candle burns?
The heated wax molecules combine with oxygen molecules.
When a solid is changed to a liquid phase, the so
absorbs energy.
When a solid is changed to a liquid phase, the solid
absorbs energy.
The systematic names for water, ammonia, and methane are dihydrogen monoxide, H2O; trihydrogen nitride, NH3; and tetrahydrogen carbide, CH4. Why do most people, including chemists, prefer to use the common names for these compounds?
all of the above
The proper name for the chemical compound NH4NO3 is
ammonium nitrate.
Matter is made up of basic units called
atoms.
Is the following transformation representative of a physical change or a chemical change?
chemical change because the atoms are connected differently
Which science is most focused on developing products for consumer use?
chemistry
The proper name for the chemical compound N2O is
dinitrogen oxide
Food in a pressure cooker is cooked faster because of the
higher temperature
One example of a periodic trend is the
increase in atomic size moving from left to right across the periodic table.
Compared to chemical changes, physical changes typically involve
less energy and reversibility.
Double the absolute temperature of helium gas, and the molecules of helium, on average, speed up by
less than twice
To melt 50 g of 0°C ice requires
none of the above
The phase in which atoms and molecules no longer move is the
none of these
A solid is not considered fluid because
of the fixed arrangement of its atoms or molecules.
Elements within the same ________ tend to vary in a gradual way.
period
Basic research is to applied research as theory is to
practice
Increased air pressure on the surface of hot water tends to
prevent boiling.
One atomic mass unit is approximately equal to the mass of a
proton.
When a gas is changed to a liquid phase, the gas
releases energy
When heat is added to boiling water, water temperature
stays the same.
Gases are so much easier to squeeze into smaller volumes than liquids or solids because
there is so much space in between the submicroscopic particles.
We are warmed by condensation because water molecules in the air that strike our bodies
transfer some of their kinetic energies to us.
Evaporation is a cooling process and condensation is
warming process
Suppose you walk on red hot coals with bare feet. Providing bits of coal do not stick to your feet, it would be best if your feet are
wet
Some of the older known elements are the ones
whose atomic symbols and modern name don't match.
