CREATING COMPOUNDS: INVESTIGATING CHEMICAL CHANGES

Chlorophyll a is one of the green pigments found in plants. Chlorophyll a has the molecular formula C 55 H 72 MgN 4 O 5 . How many atoms are in this molecule?

137

Which of the following is not a phase change?

Hydrogen and Oxygen gas combining to form water vapor

Phase Change

A change from one state of matter to another

Physical Change

A change in shape, size, or physical characteristics but remaining same substance

Law of Constant Composition

A pure compound consists of exactly the same elements in the exact same ratios by mass

Fill in the physical properties of oxygen cited in the text:

Color: Colorless Solubility in Water: Slight Freezing Point: -128 Boiling Point: -183

The process of passing electricity through water to chemically separate it into hydrogen and oxygen is called what?

Electrolysis

Classify each of the following as a physical change or a chemical change.

Grinding Glass: Physical Rusting of Iron: Chemical Burning a Candle: Chemical Sanding Wood: Physical

The molecular formula for caffeine is C 8 H 10 N 4 O 2 . Which of the following elements is not found in caffeine?

Helium

Plants make glucose by a chemical process called:

Photosynthesis

Molecule

The smallest unit of a compound

Chemical Change

The starting materials completely lose their properties to form new substances

Iron filings can be separated from a mixture with sulfur by using a magnet.

True

The various components of a mixture do not combine chemically.

True

Unknown compounds can usually be identified based solely on their physical properties.

True

Classify each of the following as a physical change or a chemical change.

Melting Ice: Physical Souring of Milk: Chemical Digesting Food: Chemical Evaporating Water: Physical