FOR FUTURE FLVS STUDENT

What is the approximate boiling point of the substance represented by the complete heating curve below?

0°C

10°C

20°C

30°C <------answer

__________

The heating curve below shows the temperature change that occurs as a solid is heated. What is occurring at segment DE of the graph?

melting

freezing

boiling<------- answer

condensing

_

The cooling curve below represents the cooling of a sample of gas. According to the diagram, what phase(s) would you expect to observe when the substance is at 300 Kelvin?

gas

gas and liquid

liquid <----- answer

liquid and solid

____

When placed in a freezer, liquid water turns into solid ice. Why is this considered a physical change?

The physical structure of the water molecules change as bonds are broken and atoms are rearranged.

Only the motion and arrangement of the particles changes, not the identity of the substance. <------- ANSWER

The water molecules react when exposed to the cold temperature, causing the atoms to separate.

Only the arrangement of the atoms within the molecules changes, not the distance between them.

_

In which of these samples do the atoms have the greatest kinetic energy?

liquid iron (2,000°C)<----- ANSWER

liquid iron (1,600°C)

solid iron (65°C)

solid iron (25°C)

Describe in your own words, in terms of particle movement and energy, what occurs when a liquid is heated to its boiling point.

MY ANSWER GOT 4/4

It is a physical change, b/c the chemical identity of the matter doesn't change. Just think about water: as it freezes, it is harder to move to less kinetic energy. So there is less free movement, and less kinetic energy as it freezes.

A scientist heats a sealed flexible container full of helium gas. What will most likely happen to the container as the gas absorbs heat?

It will shrink because the helium atoms will break apart into smaller pieces.

It will expand because the helium atoms will get larger.

It will expand because the helium atoms will move more quickly and get farther apart.^----- ANSWER

It will shrink because the helium atoms will lose energy as heat and move closer together.

______

Which of the following expands to fill the container it is in but can be compressed to a smaller volume when pressure is applied?

solid iron

liquid bromine

neon gas<------ ANSWER

sugar crystals

Question

tabbyflcca tabbyflcca

14-03-2017
Chemistry

Answered

FOR FUTURE FLVS STUDENT

What is the approximate boiling point of the substance represented by the complete heating curve below?

0°C

10°C

20°C

30°C <------answer

__________

The heating curve below shows the temperature change that occurs as a solid is heated. What is occurring at segment DE of the graph?

melting

freezing

boiling<------- answer

condensing

_

The cooling curve below represents the cooling of a sample of gas. According to the diagram, what phase(s) would you expect to observe when the substance is at 300 Kelvin?

gas

gas and liquid

liquid <----- answer

liquid and solid

____

When placed in a freezer, liquid water turns into solid ice. Why is this considered a physical change?

The physical structure of the water molecules change as bonds are broken and atoms are rearranged.

Only the motion and arrangement of the particles changes, not the identity of the substance. <------- ANSWER

The water molecules react when exposed to the cold temperature, causing the atoms to separate.

Only the arrangement of the atoms within the molecules changes, not the distance between them.

_

In which of these samples do the atoms have the greatest kinetic energy?

liquid iron (2,000°C)<----- ANSWER

liquid iron (1,600°C)

solid iron (65°C)

solid iron (25°C)

Describe in your own words, in terms of particle movement and energy, what occurs when a liquid is heated to its boiling point.

MY ANSWER GOT 4/4

It is a physical change, b/c the chemical identity of the matter doesn't change. Just think about water: as it freezes, it is harder to move to less kinetic energy. So there is less free movement, and less kinetic energy as it freezes.

A scientist heats a sealed flexible container full of helium gas. What will most likely happen to the container as the gas absorbs heat?

It will shrink because the helium atoms will break apart into smaller pieces.

It will expand because the helium atoms will get larger.

It will expand because the helium atoms will move more quickly and get farther apart.^----- ANSWER

It will shrink because the helium atoms will lose energy as heat and move closer together.

______

Which of the following expands to fill the container it is in but can be compressed to a smaller volume when pressure is applied?

solid iron

liquid bromine

neon gas<------ ANSWER

sugar crystals

Verified Answer :

Answers:

1. (D) 30°C

A good example that most people are familiar with is the heating of water. If we take a beaker packed with ice (solid water) and put in on a hot plate that has a temperature of 120 ° C we all know what will happen. First, the ice will dissolve to liquid water. Then the water will rise in temperature. Then ultimately the water will boil. During this complete process, the temperature of the hot plate will be greater than the temperature of the beaker of water. Thus, during this whole process energy will move in the form of heat from the hot plate into the water.

2. (C) Boiling

When a system comprises only one phase (solid, liquid or gas), the temperature will rise when it gets energy. The rate of temperature rise will be dependent on the heat capacity of the phase in the system. When the heat capacity is high, the temperature rises slowly because much energy is needed to increase its temperature by one degree. Thus, the slope of temperature rise for the solid, liquid, and gases varies.

3. (C) Liquid

A cooling curve is a line graph that describes the difference of phase of matter, typically from a gas to a solid or a liquid to a solid. The independent variable is time and the dependent variable is temperature. The original point of the graph is the starting temperature of the matter, regarded as the "pouring temperature".

4. Only the motion and arrangement of the particles changes, not the identity of the substance.

Water is held together by hydrogen bonds, the soundest of inter-molecular forces. This is where a hydrogen atom in one molecule is completely attracted to an electronegative atom (in this case, oxygen) in the other. When sufficient energy is absorbed by H2O, the molecules vibrate so vigorously that these bonds are loosened, giving them scope to bounce around. When this energy is taken out of the H2O, this transmits room for hydrogen bonds to tighten, squeezing collectively to form a solid.

5. liquid iron (2,000°C)

The kinetic energy of an object is the energy that it controls due to its motion. It is described as the work needed to stimulate a body of a given mass from rest to its stated velocity. Having obtained this energy during its acceleration, the body keeps this kinetic energy unless its speed changes.

6.

Boiling is the method by which a liquid changes into a vapour when it is burned to its boiling point. The transition from a liquid phase to a gaseous phase happens when the vapour pressure of the liquid is similar to the atmospheric pressure used on the liquid. Boiling is a physical change in which molecules are not chemically altered during the process. When atoms or molecules of a liquid are ready to expand out enough to change from a liquid phase to a gaseous phase, bubbles form and boiling occurs

7. (C) It will expand because the helium atoms will move more quickly and get farther apart.

Over a period of centuries and through various experiments, physicists and chemists have been equipped to describe key characteristics of a gas, including the volume it controls (V) and the pressure it exerts on its enclosure (P), to temperature (T).

8. (C) Neon Gas

Neon is a colourless, odourless, inert monatomic gas under regular conditions, with about two-thirds the density of air. It was recognized as one of the three residual rare inert elements surviving in the dry air after nitrogen, oxygen, argon and carbon dioxide were evacuated. Neon was the second of these three rare gases to be found and was immediately identified as a new element from its bright red emission spectrum.