Chemical Changes, Physical Changes, & Mixtures

Question 0

What is a catalyst?

Answer 0

Sparks a chemical reaction, such as a spark

Ex. Fire being started is chemical reaction

Question 1

What is a chemical change?

Answer 1

Chemical composition

Fuel burning. Propane being used

Ex.

C3H8 + 5O2 —> 3CO2 + 4H20

All atoms must remain after change

Question 2

What is a mixture?

Answer 2

Material that can be separated by physical means into two or more substances

Question 3

What is a solution?

Answer 3

A homogenous (even throughout) mixture in which one substance has dissolved into the others

Ex. Saline solution, saltwater

Question 4

What is suspension?

Answer 4

System in which small particles are kept dispersed by agitation or molecular motion in the surrounding medium

Ex. Muddy water in river - churned up and mixed in the river

Question 5

What is a physical change?

What are the states of matter they can change to?

Answer 5

Physical change is a change from one state to another without a change in chemical composition

3 states of matter

1. Solid
2. Liquid
3. Gas

Question 6

Explain similarities and differences in solids, liquids, & gas

Answer 6

1. Solid (coldest)
   - cannot be compressed
   - does not take shape of container
2. Liquid
   - cannot be compressed
   - does take the shape of container
3. Gas (hottest)
   - can be compressed
   - does take shape of its container

Question 7

Are boiling points and freezing point different for various substances?

Answer 7

Yes

Question 8

What are the two factors that can cause a substance to change states?

Answer 8

1. Temperature
2. Pressure - less pressure causes a lower boiling point
   Ex. In a mtn.

Question 9

If there a lot of pressure on an object the more it wants to be a ?

Less pressure?

Answer 9

More pressure - solid

Less pressure - gas

More pressure causes molecules to be stuck

Question 10

Explain Charles’ law of gas

Answer 10

Higher temperature = higher volume
Lower temp = lower volume

Pot lid is lifted when boiling water

Question 11

Explain Boyle’s law of Gas

Answer 11

Higher Pressure = lower volume
Lower pressure = higher volume

Pressure of a deep pool will shrink a ballon

Low pressure of the air causes a ballon to float away and grow

Question 12

What is pH?

How is pH measured?

Answer 12

Potential for hydrogen

A measure of the presence of hydrogen ions in a substance. It affects its propensity to bond with other substances

pH is measure using a litmus test

Question 13

What are the ends of a pH scale?

Answer 13

Acid
- negative numbers

Alkaline (Base)
+ positive numbers

7 is pure water
The further you go from 7 in either direction causes more costic (burning/damaging) substances

Question 14

Cleansers tend to be?

Biological (food substances)?

Answer 14

Cleansers - alkaline (base)

Biological (food substances) - acidic