6.1 When Substances Change Flashcards

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1
Q

In what type of change does a new substance form in?

A

Chemical change

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2
Q

Is a physical change reversible?

A

Usually it is

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3
Q

What may change in a physical change even though no new substance is formed?

A

The physical properties

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4
Q

What changes occur in physical changes?

A

Shape or form, expansion and contraction, change of state or mixing substances together.

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5
Q

How does an object change shape or form?

A

When force is applied, breaking, bending, stretching, crushing, twisting or compressing the object

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6
Q

When does expansion and contraction occur?

A

They occur when the temperature of the substance increases or decreases.

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7
Q

Does an object take up more or less space when heated?

A

More space

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8
Q

What happens to the volume when an object is expanded?

A

The volume increases, density decreases and no new substance is formed.

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9
Q

How does an object contract?

A

When it is cooled it contracts

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10
Q

What happens to the volume and density when an object is cooled?

A

The volume increases while the density decreases

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11
Q

What do thermometers use to show a temperature change?

A

The expansion and contraction of mercury and ethanol.

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12
Q

What happens to the state of an object if enough heat is applied to it?

A

It expands and changes state and the other way round if an object is cooled enough it contracts and changes state.

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13
Q

What change of state occurs in melting?

A

Solid to liquid

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14
Q

What change of state occurs in evaporation?

A

Liquid to gas

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15
Q

What change of state happens in condensation?

A

Gas to liquid

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16
Q

What change of state occurs in freezing/solidification?

A

Liquid to solid

17
Q

What change of state occurs in sublimation?

A

Solid to gas

18
Q

What change of state occurs in deposition?

A

Gas to solid

19
Q

What are some things that show you a chemical change has occurred?

A

Seeing a colour change,
Smelling a gas or seeing bubbles,
Seeing a new solid forming a clear solution (precipitate),
Observing an energy change, produced or absorbed.

20
Q

How can we tell a permanent colour change has occurred?

A

See a new substance has formed,
Has a new colour than the one it started with,
If you burn a match, the piece of paper or piece of toast, it produces carbon,
A physical change can also cause a colour change.

21
Q

What is a way that gas can be observed in a chemical change?

A

Bubbles, smell a new smell or see smoke

22
Q

How is a precipitate formed?

A

When two solutions are mixed, they occasionally form a solid. The solid falls out of the solution and sinks to the bottom, it occurs in pipes and drains. It is also formed when a gas is bubbled through a liquid.

23
Q

When a chemical change occurs and energy is produced, what is the energy called?

A

Exothermic

24
Q

When a chemical change occurs and energy is absorbed, what do we call that energy?

A

Endothermic

25
Q

What energy does exothermic energy produce?

A

Heat, light and sound

26
Q

What are some examples of exothermic energy?

A

Fireworks, firing a bullet, sparklers, when your body turns food into energy

27
Q

What is an endothermic chemical change?

A

A chemical change that absorbs energy from its surroundings.

28
Q

Is a physical change endothermic or exothermic?

A

It can be both

29
Q

Why do you feel cooler when you sweat?

A

Because your sweat evaporates and absorbs heat from your skin.

30
Q

Is condensation endothermic or exothermic?

A

Exothermic because it can condense on your skin releasing hot energy.