Which are easier to reverse - chemical or physical changes
Where does rusting start
A car's paint could get chipped rusting starts there
What people call a chemical change
A chemical reaction
Sodium carbonate
A harmless solid
The substances of stainless steel
Chromium is mixed with nickel with the other substances in steel
Signs of a chemical changes
Color change, formation of a gas, and heat changes
The reaction between vinegar and baking soda
Example of a chemical change
Cookware in the kitchen
Exposed to moisture
Do foods contain sulfur?
Foods contain sulfur, particularly eggs
What happens when baking soda and vinegar are mixed
Gas bubbles form
How to remove tarnish
Polish the tarnished item
How chemical changes occur
Chemical changes occur when atoms link together in new ways
Rocket engines use a lot of heat
Chemical reactions produce lots of heat
What happens when solid fuel burns
Aluminum powder is converted to aluminum oxide
New substances formed by chemical reactions
Called products
The original substances of chemical changes
Called reactants
Special type of steel
Called stainless steel
Unburning toast
Can not unburn toast
Unspoil milk
Can not unspoil milk
Ingredients of baking soda and vinegar
Carbon dioxide gas, water, and sodium acetate
The new substance of baking soda and vinegar
Creates carbon dioxide, and other new substances you can not see
Reversing chemical changes
Difficult to reverse
How to slow down rusting
Painting or oiling steel and other complex steel
The chemical change of a cake
Heat turns the baking soda in the cake dough into sodium carbonate, steam, and carbon dioxide gas
The bubbles of carbon dioxide in the cake
Help the dough expand and make the cake light and fluffy
The steam in the cake
Helps make the cake moist
Wax into carbon dioxide
Turns into carbon dioxide gas and steam when it combines with oxygen in the air
What does zinc do?
In moist air zinc form a self - protecting coating
Iron oxide
Is a red powder, commonly known as rust
Objects covered by tarnish
Is silver sulfide
The reaction of rust
Is very complex and needs moisture to occur
Where is rusting starting
It comes in side to out
Reversing sugar water
Let the water evaporate
Reversing an ice cube
Melting an ice cube can be easily be reversed by cooling it until it freezes again.
The wax of a burning candle
Melts, runs down the side and turns solid again
What produce small amounts of hydrogen sulifde
Mineral springs contain small amounts of hydrogen sulfide
Galvanizing bath
Objects are given a thin coat of zinc
The main engines of space shuttle
Powered by liquid nitrogen and liquid oxygen
The affect of rusting
Rust eats through iron containing metals and weakens the metal which makes the metal destroyed
Reversing physical changes
Sometimes easy to reverse
How rust occurs
Steel objects are most likely to rust if they get wet and not dried right away
Making the candle flame
The change releases enough heat to make the candle flame
Properties of chemical change
The new substances have properties different from the original substances from which they formed
The chemical reactions formed in the cake
These chemical changes strengthen the cake and keep it from collapsing after it is baked
When liquid nitrogen and liquid oxygen
They make water vapor
The heat of the oven on the cake
Triggers other chemical changes in the cake batter
What the shuttle boosters use
Uses a solid fuel
How rust forms
When iron atoms in steel react with oxygen from the air
How silver sulfide forms
When silver in the object reacts with sulfur or hydrogen sulfide in food or the air
Reversing a piece of paper after cutting it
Will not be easy to put the paper back after cutting it
How to prevent rusting in those places
You could sand or repaint those places
How to tarnish silver
You could wrap it with a rubber band
Does zinc rust?
Zinc does not rust
Does zinc protect steel?
Zinc protects the inner coat of metal objects from rusting
