Chemical Changes Flashcards
(20 cards)
What is a chemical change?
A chemical change changes the nature and characteristic properties of matter. It produces 1 or more new substances.
What is the law of conservation of mass?
The law is that nothing is lost, nothing is created, all is transformed. You must have the same amount of atoms on each side
chemical changes are expressed in an equation. There are reactants on the left, products on the right. How can we know if a chemical change has occurred?
Clues: The release of gas changes of heat Generation of light Change of colour Formation of a precipitate
What is synthesis?
Synthesis is forming a complex molecule from atoms or simple molecules
When energy in the equation is with the reactants, it is…
Absorbing energy
When energy is on the products side in an equation, it is…
Releasing energy
What types of synthetic reactions take place in living beings?
Photosynthesis and cellular respiration
What is decomposition?
Decomposition is the transformation of complex molecules into simple molecules. It is the opposite of synthesis. It makes a complex molecule into a simple molecule, while synthesis makes a simple molecule into a complex molecule
What happens at the end of decomposition?
The energy that was stored in the molecule is released and transformed into other types of energy
What is oxidation?
Oxidation is a chemical reaction involving oxygen or substance that has similar properties to oxygen like oxygen sulfur and chlorine
What’s an example of oxidation?
The formation of rust on metal.
Can only metal oxidize?
No
What is the role of energy in oxidation reactions?
Releasing energy but slowly
What is the difference between cellular respiration and photosynthesis?
Cellular respiration releases energy, but photosynthesis absorbs energy
What’s precipitation?
Precipitation is the formation of a solid (that is less soluble or not soluble) following the mixing of two solutions.
Ex: vinegar and milk
Precipitation is used as separation techniques for certain mixtures
Equation: KI + Pb(NO3)2—
What’s the role of energy in synthesis?
• It either absorbs or releases energy.
What’s the role of energy in decomposition?
The chemical energy in a molecule is usually released and transformed into another energy.
Decomposition always involves the release of energy in living organisms.
What’s the role of energy in oxidation?
- It releases energy, but in slow oxidation it’s hard to see
- combustion is an exothermic reaction, and it releases energy because it’s fast
- fire breathes oxygen
An example of oxidation is combustion. What is combustion?
It’s heat + fuel + oxygen = rapid reaction and release of energy.
It happens in our bodies: In our body, oxidation occurs. Glucose from what we eat reacts with the oxygen we breathe to give the energy to our bodies to keep warm and move around.
What is the formula for cellular respiration?
C6H12O6—
