HVAC 125- Unit 7 Properties of Matter
What is the temperature of the water formed when ice melts?
32F
What is the AHRI definition of Standard air?
Air weighing 0.075 lb/ft3, which approximates dry air at 70 F and at barometric pressure of 29.92 in Hg. (95 f outside ambient temp, 80 f indoor dry bulb temp, and 68 f indoor wet bulb temp)?
What is the difference between an atom and a molecule?
An atom is the smallest piece of an element that can exist and still retain the same chemical properties while a molecule is the smallest part of anything that is not an element.
What is matter?
Anything that has mass and takes up space
State the law of conservation of matter
Cannot create or destroy matter. Can change its form but cannot disappear.
What are the two general categories for properties of matter?
Chemical and physical properties.
What physical change of state is the opposite of boiling?
Condensing
Calculate the density, specific volume, and specific gravity of a gas that occupies 20 ft3 and weighs 2 lb
Density= 2 lb / 20 ft3 = 0.1 lb/ft3 Specific volume=20 ft3 / 2 lb =10 ft3/lb Specific Gravity= 0.1 lb/ft3 / 0.075 lb/ft3 = 1.3
Calculate the density, specific volume, and specific gravity of a solid that occupies 3 ft3 and weighs 9 lb
Density= 9 lb / 3 ft3 = 3 lb/ft3 Specific volume= 3 ft3 / 9 lb = 0.0333 ft3/lb Specific Gravity= 3 lb/ft3 / 62.4 lb/ft3 = 0.04
What physical change of state is the opposite of sublimation?
Deposition
what is condensing?
Gas to liquid
What effect does pressure have on the boiling temperature of a liquid?
Increasing the pressure increases the boiling point
if the solid in question 7 were placed in water, would it sink or float?
It will float since its specific gravity is lighter than 1
If the gas in question 5 were released in a room, would it be more likely to be found near the ceiling or near the floor?
It would be closer to the floor since it is heavier than air's 0.075
What is boiling?
Liquid to gas
Explain the difference between the weight of an object and the mass of an object.
Mass is measuring "how much" while weight is mass which is the measure of all the matter in the object of its inertia (its heavy or light)
what is the difference between the melting and the freezing point?
Melting is when Heat is added and freezing is when heat is removed
List the three states of matter in order of their energy level, from lowest to highest.
Solid, liquid, gas.
Give a practical application in the HVACR industry for specific gravity.
Specific gravity of fuel gas. Because of this piping has charts that specify the specific gravity of gas they are designed for.
What is the substances critical point?
Temp and pressure where the liquid state no longer exists.
explain the relationship between specific volume and density.
They both use the same information just switched around.
Why are testing standards important when specifying density and specific volume
They require reference temp and pressure to be done correctly since volume and gas varies with temp and pressure.
What is deposition?
gas to solid
What is sublimation?
solid to gas
What is Critical point?
the temperature and pressure at which liquids and gases become indistinguishable
What is triple point?
the temperature and pressure at which the solid, liquid, and vapor phases of a pure substance can coexist in equilibrium.
