Chapter 3 – Matter and Energy Matter - Has mass and takes ...

Chapter 3 – Matter and Energy

Matter - Has mass and takes up space- Stuff that things are made of

3 common states of matter:

Solid – Fixed shape and volume

Liquid – definite volume, variable shape

Gas – no fixed shape or volume

Physical Property – A property of matter that can be determined without changing the substance.

Examples: color, smell, density, melting point, bo iling point,..

Physical Change – Change in state of matter

Example: boil water, molten iron solidifies,..

Chemical Property – A property of matter that is det ermined by changing the substance.

Examples: Flammability, corrosiveness, reaction wi th acid or water, …

Chemical Change – When a substance changes to anothe r substance.

Example: Burn wood, blow up dynamite.

Chemical or physical properties?

The boiling point of alcohol is 78 oC

Diamonds are hard.

Sugar ferments to alcohol

Metal wire is conductive to electricity

Chemical or Physical Change?

Ice forms on a lake

Wood is burned

Seawater is distilled

Element – pure substance that cannot be broken down further by chemical means.

ex. Aluminum, iron, oxygen

Elements can occur as single atoms or aggregates… He vs. O2

Allotropes – varying multiples of the same element

ex. Oxygen = O 2Ozone = O3

Compound – 2 or more types of elements bonded togeth er

Hydrogen + Oxygen → Water

Homogenous Mixture – same throughout, and does not separate.

Heterogeneous Mixture –Different throughout, and will separate into different components.

2 Types of Mixtures:

Separation of mixtures:

1. Distillation – used to separate a mixture of 2 o r more substances, based on different boiling points. Bes t for homogenous solutions.

i.e. salt water

2. Filtration – used to separate a solid from a liqui d. Usually best for heterogeneous solutions

i.e. Coffee grounds from coffee

Energy – the capacity to do work- allows us to do things.

1 way we use energy is to change the temperature of a substance.

Heat – A type of energy that is transferred from a w armer to cooler object.

Temperature – a measure of how fast molecules are mo ving.

Heat and temperature are not the same thing! To wa rm a substance, heat energy is added, which increases vibrational motion, and thus, temperature.

Units of temperature oF, oC, and Kelvin

Units of heat are:

1 calorie (c) = the amount of energy required to ra ise 1 gram of water by 1 oC.

1 Calorie (C) = nutritional calorie = 1000 calorie s= 1 Kcal

1 calorie = 4.184 Joules (J)

Problem: convert 60.1 calories to to kJ

Specific Heat – The amount of energy required to rai se 1 gram of a substance by 1 oC.

q = m s ∆t where q = heatm = mass (g)s = specific heat∆t= t2 - t1 (oC or Kelvin)

Problem: calculate the number of joules needed to heat 5.63 grams of gold from 21 oC to 32 oC.

Problem: Calculate the number of Calories needed t o warm your shower water from 40 oF to 99 oF. Assume that your shower is 10 minutes long, and that you have a flow restrictor on your shower head that limits water consumption to 3 gallons/minute.

Problem: 1.6 grams of yellow metal requires 5.8 J to raise its temperature from 23 oC to 41 oC. Is it pure gold?

Over time, what will happen to the temperatures of the 2 boxes of water?

What would happen if hot metal (80 oC) were placed into cold water (25 oC)?

mH2O sH2O∆tH2O= -( mmetal ) (smetal ) (∆t metal )

Problem: 10.0 g pure metal at 60.0 oC is placed in 39.6 g of 25.0 oC water. The final temperature of the water and metal is 25.5 oC. What is the metal?