Chemical or Physical?

Ice cream melting.

Physical change because no new substance is formed. No energy was added.

Burning wood.

Chemical because ash and soot are made from adding energy in the form of fire to make new substances.

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.

Chemical because carbon dioxide gas was produced - bubbles.

The changing of starch into sugars by enzymes in the digestive system represents:

Chemical because digestion takes place in the stomach with acids.

In a fireworks show, the fireworks explode giving off heat and light.

Chemical because energy is given off through the heat and light.

You take out your best silver spoons and notice they are very dull and have some black spots.

Chemical because the color change is tarnish.

Your best 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.

Chemical because there is a change in color and the smoke is a change of substance.

You forgot to dry the bread knife when you washed it and reddish brown spots appeared on it.

Chemical because water + metal = rust. A new substance was formed.

Acid rain damaging marble.

Chemical change because it Sulfur Dioxide is formed.

Combining hydrogen and oxygen to make water.

Chemical reaction to form a new substance...water.

A student removes a loaf of bread hot from the oven. The student cuts a slice off the loaf and spreads butter on it.

Physical because

Food color is dropped into water to give it color.

Physical because color is added and there was no reaction or energy used.

Breaking up concrete.

Physical because the broken concrete is still concrete.

You blow dry your wet hair.

Physical because the dry hair is the same as wet hair.

Chewing food to break it down into smaller particles represents:

Physical because the food is just being broken down.

A straight piece of wire is coiled to form a spring.

Physical because the wire hasn't changed whether it is coiled or straight.

Changing the size and shape of a piece of wood.

Physical because the wood is still wood.