1. According to the phase diagram for water, how is the state of water determined?
a. proceed up a vertical line at any given temperature
b. read the phase at the intersection of any given temperature and pressure
c. at a given pressure, proceed horizontally to the S-L or L-G line
2. Temperature is a direct measurement of the energy contained in a substance.
a. True
b. False
3. Why does an evaporating liquid cool down, according to the Kinetic Molecular Theory?
a. Heat is required to evaporate a liquid.
b. Heat is lost through elastic collisions.
c. The highest velocity molecules are lost.
d. Heat must be dissipated to break the liquid bonds.
the answer in number 1 is b
1. According to the phase diagram for water, the state of water is determined by b. reading the phase at the intersection of any given temperature and pressure.
2. Temperature is a direct measurement of the energy contained in a substance. This statement is a. true.
3. An evaporating liquid cools down according to the Kinetic Molecular Theory because d. heat must be dissipated to break the liquid bonds.
1. According to the phase diagram for water, the state of water is determined by reading the phase at the intersection of any given temperature and pressure. Option b. "read the phase at the intersection of any given temperature and pressure" is the correct answer.
To determine the state of water, you need to locate the temperature and pressure on the phase diagram and find the point where they intersect. At that intersection point, you can determine whether water is in a solid (S), liquid (L), or gas (G) state.
2. Temperature is a direct measurement of the energy contained in a substance.
a. True - This statement is true. Temperature is a measure of the average kinetic energy of the particles in a substance. As the particles move with more energy, the temperature increases.
3. An evaporating liquid cools down according to the Kinetic Molecular Theory because heat is lost through elastic collisions. Option b. "Heat is lost through elastic collisions" is the correct answer.
When a liquid evaporates, the molecules with the highest kinetic energy escape from the liquid's surface, leaving behind molecules with lower average kinetic energy. These remaining molecules have a lower average kinetic energy, resulting in a decrease in temperature. This cooling effect is due to the transfer of energy from the liquid to the escaping molecules.
Options a, c, and d are not correct:
- Option a. "Heat is required to evaporate a liquid" doesn't explain why an evaporating liquid cools down. It simply states that heat is necessary for the process of evaporation to occur.
- Option c. "The highest velocity molecules are lost" is not a complete explanation of why an evaporating liquid cools down. While it is true that the highest velocity molecules are lost during evaporation, the cooling effect is due to the decrease in average kinetic energy of the remaining liquid molecules.
- Option d. "Heat must be dissipated to break the liquid bonds" is also not a complete explanation of why an evaporating liquid cools down. While heat is required to break the intermolecular bonds in a liquid, the cooling effect is primarily due to the loss of high-energy molecules during evaporation.