Question

community, matter & changes class activity
per:__ date__ chemistry
answer all questions and use the spaces provided. you may attach extra sheet as need be.
i. matter and properties
what is a physical property?
what is a chemical property?
description explanation p/c description explanation
blue color
melting point
reacts with acid
luster
density
supports combustion
reacts with water
odor
flammability (burns)
sour taste
hardness
reacts with air
solubility (dissolves)
waterfall
ii. matter and changes
what is a physical change?
what is a chemical change?
scenarios p/c change evidence/s
you blow dry your wet hair.
you forgot to dry the bread knife when you washed it and reddish - brown spots appeared on it.
in baking biscuits and other quick breads, the baking powder reacts to release carbon dioxide bubbles. the carbon dioxide bubbles cause the dough to rise.
your friend decides to toast a piece of bread, but leaves it in the toaster too long. the bread is black and the kitchen if full of smoke.
ehn! a student removes a loaf of bread hot from the oven. the student cuts a slice off the loaf and spreads butter on it.
a straight piece of wire is coiled to form a spring
in a fireworks show, the fireworks explode giving off heat and light.
you take out your best silver spoons and notice that they are very dull and have some black spots.
chewing food to break it down into smaller particles represents a __ change, but the changing of starch into sugars by enzymes in the digestive system represents a __ change
food color is dropped into water to give it color.
research question. using what you know about compressibility of gases, explain why the oxygen a scuba tank is compressed
15 % point credits

Explanation:

1. Physical property: A characteristic of a substance that can be observed or measured without changing the substance's chemical identity, like color, melting - point, density, luster, odor, hardness, solubility. For example, blue color is a physical property as it can be observed without altering the substance chemically.
2. Chemical property: A property that describes a substance's ability to undergo a chemical change or reaction, such as reacting with acid, water, air, flammability, supporting combustion, sour taste. Reacting with acid is a chemical property because a new substance is formed during the reaction.
3. Physical change: A change in which the form or appearance of matter changes, but not its chemical composition. Blowing dry wet hair is a physical change as water changes from liquid to gas, and no new substance is formed.
4. Chemical change: A change in which one or more new substances are formed. Rusting of a bread - knife is a chemical change as iron reacts with oxygen in the air to form iron oxide (rust).

Answer:

I. Matter and properties

Description	P/C	Explanation
melting point	P	Measured without altering chemical composition
density	P	Measured without chemical change
reacts with water	C	Forms new substances in the reaction
flammability (burns)	C	Undergoes a chemical reaction with oxygen
hardness	P	Observed without chemical change
solubility (dissolves)	P	Physical state change without new substance formation
reacts with acid	C	New substances are formed in the reaction
luster	P	Observed without chemical change
supports combustion	C	Participates in a chemical reaction
odor	P	Detected without chemical change
sour taste	C	Chemical interaction with taste - buds indicating a chemical property
reacts with air	C	Forms new substances by reacting with air components
Waterfall	P (if referring to physical appearance of water flow)	Physical flow of water without chemical change

II. Matter and changes

Scenarios	P/C change	Evidence/s
You forgot to dry the bread knife when you washed it and reddish - brown spots appeared on it.	C	Iron reacts with oxygen to form iron oxide (rust)
In baking biscuits and other quick breads, the baking powder reacts to release carbon dioxide bubbles. The carbon dioxide bubbles cause the dough to rise.	C	New gas (carbon dioxide) is formed
Your friend decides to toast a piece of bread, but leaves it in the toaster too long. The bread is black and the kitchen is full of smoke.	C	Bread undergoes combustion, new substances like carbon are formed
A student removes a loaf of bread hot from the oven. The student cuts a slice off the loaf and spreads butter on it.	P	Physical cutting and spreading, no new substances
A straight piece of wire is coiled to form a spring	P	Change in shape, no chemical change
In a fireworks show, the fireworks explode giving off heat and light.	C	Chemical reactions occur to produce heat, light and new substances
You take out your best silver spoons and notice that they are very dull and have some black spots.	C	Silver reacts with sulfur in the air to form silver sulfide
Chewing food to break it down into smaller particles represents a P change, but the changing of starch into sugars by enzymes in the digestive system represents a C change	P for chewing, C for digestion	Chewing is physical breakdown, digestion is a chemical reaction
Food color is dropped into water to give it color.	P	No new substance is formed, just mixing

Research Question: Oxygen in a SCUBA tank is compressed because gases are highly compressible. Gases have large amounts of empty space between their particles. Compressing the oxygen reduces the volume it occupies, allowing more oxygen to be stored in a smaller space. This is a physical change as the chemical identity of oxygen remains the same.